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Environmental concentrations of irgarol, diuron and S-metolachlor induce deleterious effects on gametes and embryos of the Pacific oyster, Crassostrea gigas
... Les huîtres restent faciles à manipuler en laboratoire. Plusieurs précédentes études se sont intéressées aux tests embryolarvaires afin d'observer les effets potentiels des métaux (Beiras & His, 1994 ;Mai et al., 2012), pesticides (Akcha et al., 2012 ;Behrens et al., 2016 ;Mai et al., 2013), MP Sussarellu et al., 2016) et NP . La résistance de cet organisme au stress est également un paramètre intéressant permettant d'étudier les effets de contaminants à des niveaux de concentrations sublétales élevés. ...
... Les niveaux de pesticides mesurés dans les eaux superficielles sont généralement inférieurs aux concentrations létales pour les espèces aquatiques. Cependant, des effets néfastes sublétaux peuvent résulter d'une exposition à ces produits à des concentrations pertinentes pour l'environnement, notamment sur des stades précoces de développement, comme les larves-D chez l'huître creuse (Akcha et al., 2012 ;Mottier et al., 2013 ;Mai et al., 2013 ;Mai et al., 2020). Le Nicosulfuron 2-((((4,6-dimethoxy-(2-pyrimidinyl)amino)carbonyl)amino)sulfonyl)-N,N-dimethyl-3-pyridinecarboxamide, est un composant chimique utilisé comme herbicide. ...
... Mature oysters were cleaned to avoid any external contaminations and remove the microorganisms attached to them. Male and female oysters were induced to spawn by thermal stimulation (alternating immersion in filtered seawater of 18 C and 28 C for 30 min) or by stripping the gonad where thermal stimulation was ineffective (Mai et al., 2013;Gamain et al., 2017). Spawning males A. Bringer et al. / Environmental Pollution 260 (2020) 113978 2 and females were individually isolated in beakers (500 mL of filtered seawater) at their respective spawning temperatures (Parker et al., 2009). ...
Les microplastiques (MP) sont largement répandus dans les zones côtières et les océans du monde entier. Les MP sont préoccupants sur le plan environnemental en raison de leurs impacts potentiels sur un large éventail d’organismes marins, de sorte que l'évaluation de leur impact sur les écosystèmes est devenue une priorité de recherche. En complément, les substances phytosanitaires utilisées régulièrement en agriculture se déversent dans les milieux côtiers, par ruissellements. Ces travaux de thèse se sont focalisés sur (i) une étude exploratoire d’un site pilote des Pertuis Charentais (PC) afin d’évaluer l’importance de la contamination plastique et pouvoir évaluer leur toxicité sur (ii) les stades précoces et (iii) tardifs de développement de l’huître creuse, Crassostrea gigas. Ces travaux fournissent une première investigation de l’état de contamination plastique (macro et micro) d’un site d’étude littoral des PC, où la présence de plastiques ostréicoles ainsi que des concentrations élevées en MP dans les sédiments de plage ont été identifiés. De plus, les expérimentations menées en conditions de laboratoire contrôlées, nous informent sur le caractère toxique des MP de PE et des pesticides sur les stades précoces de développement (embryo-larvaire) de l’huitre creuse. Les pesticides dosés dans les eaux des PC ont montré des effets significatifs à des concentrations proches de l’environnement naturel alors que les MP s’avèrent toxiques pour des concentrations plus fortes. Ces effets apparaissent sur le développement, la croissance et le comportement natatoire des larves d’huitre creuse. Des expérimentations complémentaires, effectuées sur des stades plus tardifs, notamment les naissains d’huitre creuse, ont permis de montrer un comportement valvaire modifié suite à une exposition de 25 jours aux MP de type PE et au Chlortoluron, en conditions de laboratoire. Les effets intergénérationnels ont pu être observés avec l’utilisation de MP environnementaux (cocktail de PE, PP et PVC), vieillis aux abords des concessions ostréicoles. La qualité et le succès de fécondation ont été modifiés ainsi que le développement et le comportement de nage des larves-D issues de parents préalablement exposés durant deux mois. Ces premiers résultats permettront de renforcer les connaissances de la communauté scientifique et d’informer les professionnels et acteurs conchylicoles sur les risques des contaminants émergents, tels que les MP et les pesticides. Des adaptations des pratiques conchylicoles seront nécessaires afin d’éviter une probable dégradation de la qualité des eaux littorales dans les PC.
... Sperm DNA integrity has crucial importance since it will directly influence the quality of the male genome conveyed to the female one, and thus, to progeny. Concomitantly, several studies pointed out the lack of DNA repair machinery on spermatozoa from distinct species, such as Pomatoceros lamarckii (Polychaeta) (Dixon et al., 2002), Crassostrea gigas (Bivalvia) (Mai et al., 2013) and Gammarus fossarum (Malacostraca) (Lacaze et al., 2011). Therefore, the inability to repair damaged DNA, combined with their lower antioxidant defences, strongly contribute to making spermatozoa more susceptible to genotoxic agents than oocytes (Mai et al., 2013). ...
... Concomitantly, several studies pointed out the lack of DNA repair machinery on spermatozoa from distinct species, such as Pomatoceros lamarckii (Polychaeta) (Dixon et al., 2002), Crassostrea gigas (Bivalvia) (Mai et al., 2013) and Gammarus fossarum (Malacostraca) (Lacaze et al., 2011). Therefore, the inability to repair damaged DNA, combined with their lower antioxidant defences, strongly contribute to making spermatozoa more susceptible to genotoxic agents than oocytes (Mai et al., 2013). Previous studies on aquatic invertebrates' spermatozoa also found a link between the DNA damage and the abnormal development and growth of progeny (Barranger et al., 2016;Caldwell et al., 2011;Lacaze et al., 2011;Oliviero et al., 2019). ...
... Pesticides runoff from agricultural land and its misuse are a major concern (Hofstetter et al., 2010). Few studies evaluated the pesticide spermiotoxicity on non-target aquatic invertebrates, relying the available reports on the appraisal of fertilization success (and failure) (Díaz et al., 2015;Mai et al., 2013;Yang et al., 2008), while the assessment of genotoxic effects in spermatozoa remains unexplored. Herbicides, insecticides and fungicides are the most currently used pesticides (FAO and Tubiello, 2019;INE, 2018). ...
The spermiotoxic properties of aquatic contaminants might be the cause of low fertilization rate and decreased prolificacy, affecting the success of the impacted populations. The genotoxic potential of pesticides in spermatozoa as an undesirable effect on non-target organisms, namely aquatic invertebrates with external fertilization, emerges as a key question in ecogenotoxicological research. Thus, this study aimed to clarify if DNA integrity of red swamp crayfish (Procambarus clarkii) spermatozoa is affected by waterborne pesticides at environmentally relevant concentrations. By adopting an ex vivo approach, six pesticides were addressed in a short-term assay: herbicides glyphosate (9 and 90 µg L⁻¹) and penoxsulam (2.3 and 23 µg L⁻¹); insecticides dimethoate (2.4 and 24 µg L⁻¹) and imidacloprid (13.1 and 131 µg L⁻¹); fungicides pyrimethanil (2.2 and 22 µg L⁻¹) and imazalil (16 and 160 µg L⁻¹). Genotoxicity was observed in higher concentrations of glyphosate, penoxsulam, dimethoate, pyrimethanil, and imazalil. Imidacloprid was the only pesticide that did not cause non-specific DNA damage, although displaying pro-oxidant properties. Overall, the present study demonstrated the suitability of the ex vivo approach on spermiotoxicity screening, highlighting the potential ecological impact of pesticides on non-target species, such as P. clarkii, compromising sperm DNA integrity and, subsequently, the population success.
... Animals 2023, 13, 3078 6 of 10 test in oysters (Crassostrea gigas) by exposing germ cells to irganol and diuron showed that the fertilization rate decreased and abnormalities in embryo development increased in a concentration-dependent manner [38]. Methoxychlor (1,1,1-trichloro-2,2-bis [p-methoxyphenyl] ethane) is a prohibited chlorinated hydrocarbon developed as a replacement for DDT. ...
... Exposure of chemicals to germ cells of organisms in aquatic ecosystems are known to have adverse effects on fertilization and embryo development. Embryotoxicity test in oysters (Crassostrea gigas) by exposing germ cells to irganol and diuron showed that the fertilization rate decreased and abnormalities in embryo development increased in a concentration-dependent manner [38]. Methoxychlor (1,1,1-trichloro-2,2-bis [p-methoxyphenyl] ethane) is a prohibited chlorinated hydrocarbon developed as a replacement for DDT. ...
Simple Summary
In this study, the toxicity of tributyltin (TBT) was investigated. Sea urchins (Hemicentrotus pulcherrimus) were used as the experimental animals, and the embryonic toxicity of TBT was investigated by observing the fertilization and embryonic development rates of germ cells exposed to TBT. The fertilization rate exhibited decreasing trends as the concentration of TBT increased. Embryo development was delayed as the TBT concentration increased. Embryos whose development was delayed following TBT exposure progressed well when shifted to fresh media without TBT. The results showed that TBT had a negative effect on embryonic development. Embryonic development was restored on removal of TBT exposure. This result has important implications from the perspective of restoring polluted ecosystems.
Abstract
In this study, gametotoxicity and embryotoxicity experiments were performed using Hemicentrotus pulcherrimus to investigate the toxic effects of tributyltin (TBT). The effects of TBT on fertilization and embryogenesis were assessed at various concentrations (0, 0.02, 0.05, 0.09, 0.16, 0.43, 0.73, 4.68, and 9.22 ppb). The fertilization rates decreased in a concentration-dependent manner, with significant reduction following treatment with TBT at 0.05 ppb. Embryos exhibited developmental impairment after TBT exposure at each tested concentration. The frequency of developmental inhibition delay that treatment with TBT delayed embryonic development in a dose-dependent manner, with 100% of embryos exhibiting developmental impairment at 4.68 ppb. During developmental recovery tests, embryos cultured in fresh media without TBT showed advanced embryonic development. Although the observed normal development after transferring the developmentally delayed embryos to fresh media without TBT offers prospects for the restoration of contaminated environments, embryonic development remained incomplete. These results suggest that TBT adversely affects the early embryonic development of H. pulcherrimus.
... These effects were also evaluated in three different conditions: (i) individuals floating in the sea water, (ii) individuals settled on the dish's glass bottom surrounding the coated plate, and (iii) individuals settled on the coated paint. Generally, the most commonly used approach for understanding the action of antifouling compounds is the direct exposure of embryos or larvae of marine invertebrates to various concentrations of a single biocide in sea water with controlled parameters, totally excluding the interaction of matrix, pigments, solvents, and other additives [35][36][37][38][39][40][41]. In this way, larval toxicity and the effects on metamorphosis can be clearly observed, elucidating the possible mechanisms of action at both cellular and subcellular levels. ...
... Generally, the most commonly used approach for understanding the action of antifouling compounds is the direct exposure of embryos or larvae of marine invertebrates to various concentrations of a single biocide in sea water with controlled parameters, totally excluding the interaction of matrix, pigments, solvents, and other additives [35][36][37][38][39][40][41]. In this way, larval toxicity and the effects on metamorphosis can be clearly observed, elucidating the possible mechanisms of action at both cellular and subcellular levels. ...
To evaluate the effects of antifouling paints and biocides on larval settlement and metamorphosis, newly hatched swimming larvae of the compound ascidian Botryllus schlosseri, a dominant species of soft-fouling in coastal communities, were exposed to (i) substrata coated with seven antifouling paints on the market containing different biocidal mixtures and types of matrices and (ii) sea water containing various concentrations of eight biocidal constituents. All antifouling paints showed high performance, causing 100% mortality and metamorphic inhibition, with ≥75% not-settled dead larvae. All antifouling biocides prevented the settlement of larvae. The most severe larval malformations, i.e., (i) the formation of a bubble encasing the cephalenteron and (ii) the inhibition of tail resorption, were observed after exposure to metal and organometal compounds, including tributyltin (TBT) at 1 μM (325.5 µg L−1), zinc pyrithione (ZnP) at 1 μM (317.7 µg L−1), and CuCl at 0.1 μM (98.99 µg L−1), and to antimicrobials and fungicides, including Sea-Nine 211 at 1 μM (282.2 µg L−1) and Chlorothalonil at 1 μM (265.9 µg L−1). The herbicides seemed to be less active. Irgarol 1051 was not lethal at any of the concentrations tested. Diuron at 250 μM (58.2 mg L−1) and 2,3,5,6-tetrachloro-4-(methylsulphonyl)pyridine (TCMS pyridine) at 50 μM (14.8 mg L−1) completely inhibited larval metamorphosis. These results may have important implications for the practical use of different antifouling components, highlighting the importance of their testing for negative impacts on native benthic species.
... The embryonic and larval stages of bivalves are often reported as being the most sensitive to environmental stress (Mai et al., 2012;Geffard et al., 2002;His et al., 1999). The Pacific oyster (Crassostrea gigas), especially in early development stages, is commonly used for toxicity assessment of marine pollutants, because of its high sensitivity to a large range of pollutants, particularly pesticides (Wessel et al., 2007;Akcha et al., 2012;Mottier et al., 2013;Mai et al., 2013;Mai et al., 2014;Gamain et al., 2016). The Charente River has a vast watershed, distributed mainly over the departments of Charente and Charente-Maritime (Munaron, 2004). ...
... In the study conducted by Gamain et al. (2016), the effects of S-Metolachlor on development were observed from 0.01 μg.L −1 . In a previous study (Mai et al., 2013), Diuron, Irgarol and S-Metolachlor induced embryotoxic effects on oyster larvae at concentrations close to those found in Atlantic coastal areas. ...
This study aims to assess the toxic effects and the potential risk of widely used agricultural pesticides on the development (malformations and developmental arrest), growth and swimming activity of oyster D-larvae (Crassostrea gigas). Freshly fertilized oyster embryos were exposed for 24 h at 24 °C to different concentrations (0, 0.01, 0.1, 1 and 10 μg.L⁻¹) of six different pesticides: Glyphosate and its commercial solution (Roundup), Isoproturon, Nicosulfuron, Chlortoluron and Boscalid. The six pesticides tested induced a significant increase in larval malformations and developmental arrests. All pesticides except Glyphosate and Isoproturon affected larval growth. Roundup, Nicosulfuron, Chlortoluron and Boscalid also affected the swimming behaviour of the D-larvae, with a significant decrease recorded in their maximum swimming speed. Comparison of the LOEC (Lowest-Observed-Effect Concentration) of each compound led to the following toxicity classification: Boscalid > Chlortoluron = Nicosulfuron > Glyphosate > Roundup > Isoproturon, with respectively LOEC of 0.0028; 0.015; 0.017; 0.11; 0.3 and 0.78 μg.L⁻¹. By comparison of the maximum concentrations in the Pertuis Charentais (South West, France) and LOEC of each pesticide, the following risk scale was obtained: Chlortoluron > Boscalid > Glyphosate > Roundup > Nicosulfuron > Isoproturon. Our results revealed that Chlortoluron, Boscalid and to a lesser extent Glyphosate represent a potential threat to early life stages of oyster living in the Pertuis Charentais marine area.
... Similairement aux spermatozoïdes, les ovocytes sont sensibles aux contaminants extérieurs (e.g. algues toxiques, Le Goïc et al., 2014;pesticides, Mai et al., 2013a;métaux;Mai et al., 2013b). Généralement, les ovocytes affichent une résistance supérieure aux contaminants en comparaison aux spermatozoïdes que les auteurs attribuent à la présence d'une membrane moins perméable (Mai et al., 2013a;Mai et al., 2013b;Fitzpatrick et al., 2008). ...
... algues toxiques, Le Goïc et al., 2014;pesticides, Mai et al., 2013a;métaux;Mai et al., 2013b). Généralement, les ovocytes affichent une résistance supérieure aux contaminants en comparaison aux spermatozoïdes que les auteurs attribuent à la présence d'une membrane moins perméable (Mai et al., 2013a;Mai et al., 2013b;Fitzpatrick et al., 2008). Cette présente étude avait ainsi pour objectif de déterminer la sensibilité des ovocytes de C. gigas aux nano-PS (50-NH2 et 50-COOH) afin de compléter nos analyses sur les gamètes et de pouvoir comparer leurs sensibilités respectives. ...
Depuis 70 ans, les débris plastiques dont la fin de vie a été négligée par les sociétés humaines s’accumulent dans les océans. L’évaluation des effets engendrés par cette contamination ubiquitaire est une préoccupation majeure, notamment au regard des micro- et potentiels nanoplastiques (MNP ; < 5 mm) du fait de leur biodisponibilité pour la plupart des organismes marins. L’objectif de cette thèse était de déterminer les effets des MNP sur les jeunes stades de vie d’une espèce ingénieure des habitats côtiers, l’huître creuse Crassostrea gigas. Les impacts des MNP sur ces jeunes stades sont apparus dépendants de la taille des particules. Le rapport surface/volume important des nanosphères de polystyrène (nano-PS ; 50 nm) a favorisé les interactions avec les gamètes et embryons, induisant une inhibition de la fécondation et de l’embryogénèse tandis que les microsphères (0,5 et 2 μm) n’ont causé aucun effet phénotypique visible. La toxicité des nano-PS est apparue dépendante de leurs propriétés de surface (e.g groupements chimiques, charge) qui dirigent leur agrégation dans l’eau de mer et les interactions avec les membranes biologiques. Les nano-PS cationiques, qui restent à l’échelle nanométrique dans l’eau de mer, sont à l’origine des effets toxiques les plus marqués. L’exposition embryonnaire à une dose non létale a notamment diminué les performances larvaires et modulé la réponse de la génération suivante à une réexposition embryonnaire. Toutefois, ces effets néfastes sont observés à des concentrations numéraires supposément non-représentatives de l’environnement actuel (la quantité de NP n’étant pas caractérisée en mer à ce jour), suggérant un risque limité des micro- et nanosphères de polystyrène sur les jeunes stades de C.gigas. Les prochaines études devront tenir compte de la complexité et de la réalité des MNP environnementaux (e.g. polymères, formes, contaminants adsorbés, concentrations) sur plusieurs générations de bivalves dans le but d’appréhender plus précisément le risque pour les écosystèmes côtiers.
... Mais à ce jour, bien qu'une littérature fournie existe sur la caractérisation des effets de biocides sur des larves d'huîtres en laboratoire(His & Seaman 1993;Mai et al. 2013;Sussarellu et al. 2018;Behrens et al. 2016) , l'impact direct ou indirect de ces mélanges de polluants sur le développement larvaire ou la dynamique du phytoplancton in situ n'est que peu étudié(Vázquez-Boucard et al. 2014;Mai et al. 2013;Auby & Maurer 2004). Les correspondances entre période à risque d'exposition aux pesticides sur Thau (juin-juillet) et les périodes d'échec du recrutement (juin-juillet) relevées dans le deuxième chapitre de cette thèse posent la question d'un éventuel lien qu'il conviendrait d'explorer dans une étude à venir, prenant en compte l'ensemble des facteurs environnementaux capables d'influencer ce recrutement comme par exemple le régime trophique associé in-situ.De l'importance de définir la fonction écologique "nurserie d'huître"Nos résultats permettent de mettre en avant une fonction écologique "nurserie d'huîtres" qui apparaît comme nouvelle au sein de la lagune de Thau. ...
... Mais à ce jour, bien qu'une littérature fournie existe sur la caractérisation des effets de biocides sur des larves d'huîtres en laboratoire(His & Seaman 1993;Mai et al. 2013;Sussarellu et al. 2018;Behrens et al. 2016) , l'impact direct ou indirect de ces mélanges de polluants sur le développement larvaire ou la dynamique du phytoplancton in situ n'est que peu étudié(Vázquez-Boucard et al. 2014;Mai et al. 2013;Auby & Maurer 2004). Les correspondances entre période à risque d'exposition aux pesticides sur Thau (juin-juillet) et les périodes d'échec du recrutement (juin-juillet) relevées dans le deuxième chapitre de cette thèse posent la question d'un éventuel lien qu'il conviendrait d'explorer dans une étude à venir, prenant en compte l'ensemble des facteurs environnementaux capables d'influencer ce recrutement comme par exemple le régime trophique associé in-situ.De l'importance de définir la fonction écologique "nurserie d'huître"Nos résultats permettent de mettre en avant une fonction écologique "nurserie d'huîtres" qui apparaît comme nouvelle au sein de la lagune de Thau. ...
Les lagunes méditerranéennes hébergent de nombreux usages anthropiques dont la conchyliculture depuis le début du 20ème siècle. Importée en 1970, l’huître creuse, Crassostrea gigas, s’y est adaptée parfaitement et a permis un développement ostréicole important jusqu’en 2008, année d’apparition des surmortalités de naissain liées à l’émergence d’un variant du virus OsHv1. La raréfaction du naissain et la spéculation sur ce produit ont modifié régionalement les pratiques culturales et les modes d’approvisionnement en juvéniles, avec notamment la volonté de développer une activité locale de captage. Mais le cycle de reproduction de l’espèce et le recrutement de juvéniles étaient mal connus en milieu lagunaire. Dans ce contexte, l’objectif de cette thèse est de caractériser la variabilité de la reproduction et du recrutement de l’huître creuse en lagune méditerranéenne. La configuration lagunaire offre des atouts de productivité pour le cheptel de géniteurs et de connectivité hydrodynamique pour les larves. Cependant, il apparaît que le fonctionnement écologique du système à la base de la production primaire joue un rôle essentiel sur les apports trophiques pour le succès de la reproduction des huîtres. Ce travail s’inscrit, en outre, dans le contexte d’un écosystème en voie de restauration écologique entamant un processus d’oligotrophisation dont nous décrivons les premiers effets sur le cycle de reproduction de l’huître.
... Mais à ce jour, bien qu'une littérature fournie existe sur la caractérisation des effets de biocides sur des larves d'huîtres en laboratoire(His & Seaman 1993;Mai et al. 2013;Sussarellu et al. 2018;Behrens et al. 2016) , l'impact direct ou indirect de ces mélanges de polluants sur le développement larvaire ou la dynamique du phytoplancton in situ n'est que peu étudié(Vázquez-Boucard et al. 2014;Mai et al. 2013;Auby & Maurer 2004). Les correspondances entre période à risque d'exposition aux pesticides sur Thau (juin-juillet) et les périodes d'échec du recrutement (juin-juillet) relevées dans le deuxième chapitre de cette thèse posent la question d'un éventuel lien qu'il conviendrait d'explorer dans une étude à venir, prenant en compte l'ensemble des facteurs environnementaux capables d'influencer ce recrutement comme par exemple le régime trophique associé in-situ.De l'importance de définir la fonction écologique "nurserie d'huître"Nos résultats permettent de mettre en avant une fonction écologique "nurserie d'huîtres" qui apparaît comme nouvelle au sein de la lagune de Thau. ...
... Mais à ce jour, bien qu'une littérature fournie existe sur la caractérisation des effets de biocides sur des larves d'huîtres en laboratoire(His & Seaman 1993;Mai et al. 2013;Sussarellu et al. 2018;Behrens et al. 2016) , l'impact direct ou indirect de ces mélanges de polluants sur le développement larvaire ou la dynamique du phytoplancton in situ n'est que peu étudié(Vázquez-Boucard et al. 2014;Mai et al. 2013;Auby & Maurer 2004). Les correspondances entre période à risque d'exposition aux pesticides sur Thau (juin-juillet) et les périodes d'échec du recrutement (juin-juillet) relevées dans le deuxième chapitre de cette thèse posent la question d'un éventuel lien qu'il conviendrait d'explorer dans une étude à venir, prenant en compte l'ensemble des facteurs environnementaux capables d'influencer ce recrutement comme par exemple le régime trophique associé in-situ.De l'importance de définir la fonction écologique "nurserie d'huître"Nos résultats permettent de mettre en avant une fonction écologique "nurserie d'huîtres" qui apparaît comme nouvelle au sein de la lagune de Thau. ...
The Mediterranean lagoons host many anthropogenic uses including shellfish aquaculture since the beginning of the 20th century. Imported in 1970, the Pacific oyster, Crassostrea gigas, has adapted perfectly and has allowed an important development of oyster’s industry until 2008, the year of occurence of spat outbreak related to the emergence of an Ostreid Herpes-virus μvar. The scarcity of spat and the speculation on this product changed regionally cultural practices and the supply of juveniles, with in particular the wish of developing a local activity of spat collection. However the cycle of reproduction of the species and the recruitment of juveniles were poorly known in lagoon environments. In this context, the objective of this thesis is to characterize the variability of the reproduction and the recruitment of the cupped oyster in Mediterranean lagoon. The lagoon configuration offers the advantages of productivity for the broodstock and hydrodynamic connectivity for the larvae. However, it appears that the ecological functioning of the system at the base of the primary production plays an essential role on the trophic resources for the success of oyster reproduction. This work takes place in the context of the ecological restoration under oligotrophication, which first effects we describe on the oyster's reproductive cycle
... Des effets génotoxiques similaires ont aussi été mis en évidence après exposition des larves d'huîtres à des herbicides, fréquemment rencontrés dans les milieux aquatiques, tels que le diuron (Akcha et al., 2012 ;Mai et al., 2013 ;Barranger et al., 2014). Le diuron est un herbicide à large spectre qui inhibe la photosynthèse en empêchant la production d'oxygène par blocage du transfert d'électrons au niveau du photosystème II des micro-organismes et des plantes photosynthétiques. ...
... Par ailleurs, nous avons également pu montrer que l'utilisation de sperme d'huîtres, préalablement exposées 1 heure à des herbicides, induisait une diminution du taux de fertilisation et une augmentation des anomalies de développement. Ces effets pourraient être directement liés à une diminution de la qualité du sperme (Akcha et al.,, 2012 ;Mai et al.,, 2013 ;Barranger et al., 2014) notamment en termes d'intégrité de son ADN. ...
Chapitre 3. Vulnérabilité le long du cycle de vie et effet sur l’individu
... The toxicity of copper alone, metolachlor and its metabolites, irgarol, and diuron for oyster embryos has already been investigated in previous studies (Mai et al. 2012(Mai et al. , 2013. EC 50 values of 12.5, 2332, 196, and 672 μg L −1 were obtained for copper (Mai et al. 2012), diuron, irgarol, and metolachlor (Mai et al. 2013), respectively. ...
... The toxicity of copper alone, metolachlor and its metabolites, irgarol, and diuron for oyster embryos has already been investigated in previous studies (Mai et al. 2012(Mai et al. , 2013. EC 50 values of 12.5, 2332, 196, and 672 μg L −1 were obtained for copper (Mai et al. 2012), diuron, irgarol, and metolachlor (Mai et al. 2013), respectively. In the present study, 100% larval abnormalities were recorded at the highest dose group (100×) of PM + Cu and 78.1% at the same dose of PM without spiked Cu. ...
Frequent occurrences of pesticides in the environment have raised concerns that combined exposure to these chemicals may result in enhanced toxicity through additive or synergistic interaction between compounds. Spermatozoa and embryos of the Pacific oyster, Crassostrea gigas, were exposed to different concentrations of a pesticide mixture with and without copper, mimicking the cocktail of pollutants occurring in the oyster culture area of Arcachon Bay. For the 1× exposure condition, measured concentration corresponds to a total concentration of 1.083 μg L⁻¹ for the mixture of 14 pesticides and to 6.330 μg L⁻¹ for copper (Cu). Several endpoints including larval abnormalities, DNA damage to spermatozoa and embryo and gene expression in D-larvae were investigated. Results demonstrated that pesticide mixtures in combination with or without copper induced a dose-dependent increase in embryotoxic and genotoxic effects on D-larvae from the lowest tested dose of 0.1×. Transcription of genes involved in anti-oxidative stress (cat), respiratory chain (coxI), metal detoxification (mt1 and mt2), and cell cycle arrest and apoptosis (p53) was found to be significantly downregulated while the xenobiotic biotransformation gene gst was significantly upregulated in embryos exposed to pesticide mixture with and without Cu. These findings raise the question of the possible impacts of mixtures of pesticides and metals on wild or farmed oyster populations from polluted coastal marine areas.
... These substances may reach coastal water from freshwater inputs and affect organisms that were not initially targeted. For example, measurable biological effect of S-metolachlor on marine organisms vary between levels higher than mg L −1 for microalgae growth, photosynthetic efficiency or lipid content (Ebenezer and Ki, 2013;Coquillé et al., 2018), to environmentally realistic sub μg L −1 levels causing spermio and embryotoxicity on Crassostrea gigas (Mai et al., 2013). Passive sampling is increasingly developed for a wide range of contaminants, because it provides more accurate data, e.g., time-weighted average concentrations, freely dissolved contamination fraction, high preconcentration rates decreasing limits of detection (LD). ...
... Other issues could arise when trying to implement such an approach for more hydrophobic contaminants, which might have higher affinity for suspended matter, and would therefore not be detectable in the dissolved fraction of the water column. In light of a previous study (Mai et al., 2013), implications of these results for the local economy of Arcachon Bay could be of importance, since most of the oyster farms are located close to the Leyre river mouth where Smetolachlor concentrations are the highest, eventually implying spermio and embryotoxicity. Thus, the model outputs have to be considered with caution despite their ability to predict concentrations ranges and seasonal trends, in good agreement with measurements at different points of the Bay. ...
... [3] Consequently, S-Metolachlor is toxic for aquatic animals and freshwater and should be effectively eliminated, possibly via adsorption process. [4] To find an efficient, cheap, and environmentally friendly material for S-Metolachlor adsorption, biochar made from acacia sawdust is a potential approach. Acacia (Acacia auriculiformis) is a popular plant in Vietnam [5] that have been cultivated for approximately 2.1 million ha (2019) with a supply of 20.6 million m 3 per year. ...
... Biological species, including fish (Ali et al. 2015; Moreira et al. 2018), oysters (Mai et al. 2013;Barranger et al. 2014), crustaceans (Shaala et al. 2015), and aquatic macrophytes (Lambert et al. 2005), have demonstrated sensitivity to contamination by these biocides, even at ng L −1 levels. This contamination has led to malformations and mortality, posing a risk of species extinction (Moon et al. 2019). ...
Abstracts
Diuron and Irgarol are common antifouling biocides used in paints to prevent the attachment and growth of fouling organisms on ship hulls and other submerged structures. Concerns about their toxicity to non-target aquatic organisms have led to various restrictions on their use in antifouling paints worldwide. Previous studies have shown the widespread presence of these substances in port areas along the Brazilian coast, with a concentration primarily in the southern part of the country. In this study, we conducted six sampling campaigns over the course of 1 year to assess the presence and associated risks of Diuron and Irgarol in water collected from areas under the influence of the Maranhão Port Complex in the Brazilian Northeast. Our results revealed the absence of Irgarol in the study area, irrespective of the sampling season and site. In contrast, the mean concentrations of Diuron varied between 2.0 ng L⁻¹ and 34.1 ng L⁻¹ and were detected at least once at each sampling site. We conducted a risk assessment of Diuron levels in this area using the risk quotient (RQ) method. Our findings indicated that Diuron levels at all sampling sites during at least one campaign yielded an RQ greater than 1, with a maximum of 22.7, classifying the risk as “high” based on the proposed risk classification. This study underscores the continued concern regarding the presence of antifouling biocides in significant ports and marinas in Brazilian ports, despite international bans.
Graphical Abstract
... SM is also considered an important contaminant of groundwater (PAN Pesticide Database, 2022). The effects of SM have been evaluated in fish (Quintaneiro et al., 2017;Liu et al., 2022), crabs Stara et al., 2019), crustaceans (Liu et al., 2006), and bivalve mollusks (Mai et al., 2013). In amphibians, studies on the toxic effects of Metolachlor have been conducted on Xenopus laevis (Daudin, 1802) embryos (Osano et al., 2002) and Lithobates catesbeianus (Shaw, 1802) larvae (Wan et al., 2006), and endocrine alterations have also been evaluated in adult individuals of Lithobates pipiens and L. clamitans (McDaniel et al., 2008). ...
Acute toxicity and genotoxicity of the S-metolachlor-based herbicide Dual Gold ® on Leptodactylus luctator (Hudson, 1892) tadpoles (Anura: Leptodactylidae). Herbicides used in agriculture and their metabolites are frequently detected in surface water bodies, where they can persist and cause adverse effects on aquatic organisms. The aim of this study was to evaluate the acute toxicity and genotoxic effects of the S-metolachlor (SM)-based herbicide Dual Gold ® (DG ®), on Leptodactylus luctator tadpoles (Anura: Leptodactylidae). To assess the toxicity of the herbicide, including the median lethal concentration (LC50) at 24h, the no-observed-effect concentration (NOEC), and the lowest-observed-effect concentration (LOEC), tadpoles were exposed to five nominal concentrations of DG ® (5.0, 6.2, 7.8, 9.8, and 12.2 mg/L), and to dechlorinated water as a negative control (NC). The LC50 24h of DG ® was 7.0 mg/L, the NOEC was 5.0 mg/L and the LOEC=6.2 mg/L. L. luctator tadpoles were sensitive to the herbicide, reaching 100% mortality after 24 h of exposure to the highest concentration tested (12.2 mg/L). To evaluate the potential genotoxicity of the herbicide, the frequencies of micronuclei (MN) and other erythrocyte nuclear abnormalities (ENA) were determined in larvae exposed to three nominal concentrations of DG ® (1.0, 5.0, and 6.2 mg/L) for 48 and 96 h. The frequencies of MN and ENA were compared with a positive control (40 mg/L of Cyclophosphamide) and a negative control. The frequencies of MN and ENA in the erythrocytes of tadpoles exposed to the test concentrations of DG ® and Cyclophos-phamide were significantly higher than in the negative control group at both 48 and 96 h (with the only exception of MN at 1.0 mg/L at 48 h). Our results confirm the genotoxic and cytotoxic effects of this widely used herbicide in agriculture, a fact that represents a potential risk to amphibians that develop in ponds associated with or immersed in agroecosystems.
... SM is also considered an important contaminant of groundwater (PAN Pesticide Database, 2022). The effects of SM have been evaluated in fish (Quintaneiro et al., 2017;Liu et al., 2022), crabs Stara et al., 2019), crustaceans (Liu et al., 2006), and bivalve mollusks (Mai et al., 2013). In amphibians, studies on the toxic effects of Metolachlor have been conducted on Xenopus laevis (Daudin, 1802) embryos (Osano et al., 2002) and Lithobates catesbeianus (Shaw, 1802) larvae (Wan et al., 2006), and endocrine alterations have also been evaluated in adult individuals of Lithobates pipiens and L. clamitans (McDaniel et al., 2008). ...
Herbicides used in agriculture and their metabolites are frequently detected in surface water bodies, where they can persist and cause adverse effects on aquatic organisms. The aim of this study was to evaluate the acute toxicity and genotoxic effects of the S-metolachlor (SM)-based herbicide Dual Gold® (DG®), on Leptodactylus luctator tadpoles (Anura: Leptodactylidae). To assess the toxicity of the herbicide, including the median lethal concentration (LC50) at 24h, the no-observed-effect concentration (NOEC), and the lowest-observed-effect concentration (LOEC), tadpoles were exposed to five nominal concentrations of DG® (5.0, 6.2, 7.8, 9.8, and 12.2 mg/L), and to dechlorinated water as a negative control (NC). The LC5024h of DG® was 7.0 mg/L, the NOEC was 5.0 mg/L and the LOEC=6.2 mg/L. L. luctator tadpoles were sensitive to the herbicide, reaching 100% mortality after 24 h of exposure to the highest concentration tested (12.2 mg/L). To evaluate the potential genotoxicity of the herbicide, the frequencies of micronuclei (MN) and other erythrocyte nuclear abnormalities (ENA) were determined in larvae exposed to three nominal concentrations of DG® (1.0, 5.0, and 6.2 mg/L) for 48 and 96 h. The frequencies of MN and ENA were compared with a positive control (40 mg/L of Cyclophosphamide) and a negative control. The frequencies of MN and ENA in the erythrocytes of tadpoles exposed to the test concentrations of DG® and Cyclophosphamide were significantly higher than in the negative control group at both 48 and 96 h (with the only exception of MN at 1.0 mg/L at 48 h). Our results confirm the genotoxic and cytotoxic effects of this widely used herbicide in agriculture, a fact that represents a potential risk to amphibians that develop in ponds associated with or immersed in agroecosystems.
... A exposição de estágios iniciais e gametas da C. gigas aos biocidas S-metolacloro, irgarol, diuron e metais (cobre e cádmio) isolados e misturados, levaram a anomalias de desenvolvimento, danos no DNA e alterações na expressão de genes envolvidos na resposta de estresse oxidativo (Mai, 2013). Também foi verificado o impacto de biocidas e metais em água doce (Faria et al., 2010), indicando que a toxicidade combinada dos poluentes (cobre, metil mercúrio e 4-nonilfenol) foi maior e apresentou efeitos do tipo "aditivo" em Unio elongatulus e Dreissena polymorpha. ...
O livro “Monitoramento ambiental: Metodologias e Estudos de casos” volume II apresenta novos trabalhos que abordam práticas de monitoramento ambiental em diferentes ecossistemas e utilizando diferentes organismos. Este ebook tem como objetivo alcançar pesquisadores e professores nos diferentes níveis de ensino, auxiliando na discussão da temática em sala de aula.
... A exposição de estágios iniciais e gametas da C. gigas aos biocidas S-metolacloro, irgarol, diuron e metais (cobre e cádmio) isolados e misturados, levaram a anomalias de desenvolvimento, danos no DNA e alterações na expressão de genes envolvidos na resposta de estresse oxidativo (Mai, 2013). Também foi verificado o impacto de biocidas e metais em água doce (Faria et al., 2010), indicando que a toxicidade combinada dos poluentes (cobre, metil mercúrio e 4-nonilfenol) foi maior e apresentou efeitos do tipo "aditivo" em Unio elongatulus e Dreissena polymorpha. ...
Agrotóxicos, metais, medicamentos, efluentes urbanos, petróleo e derivados são um
problema crescente para o meio ambiente e à saúde pública urbana da Amazônia. Neste estudo,
revisamos aspectos relacionados a esta temática com ênfase aos efeitos desses poluentes sobre a
qualidade da água e de organismos aquáticos. As informações levantadas permitiram inferir que
os efeitos são negativos sobre a ictiofauna, à saúde humana e aos recursos hídricos. Assim, são
necessários instrumentos jurídicos e tecnológicos que possibilitem a preservação ambiental e o
desenvolvimento socioeconômico, atrelado a forma de expansão da região, que foi traçado ao
longo dos seus cursos d'água.
... Mật độ trứng được xác định (huyền phù trứng đã pha loãng 100 lần bằng nước biển nhân tạo) từ ba lần đếm (sử dụng buồng đếm sinh vật phù du The Gridded Sedgewick Rafter) [24], sau đó, bổ sung nước biển để đạt 6000 trứng/mL [25]. Tương tự cho tinh trùng, đếm (sử dụng buồng đếm hồng cầu Haemocytometer) và bổ sung nước biển sao cho huyền phù tinh trùng đạt 2 triệu tinh trùng/mL [26,16]. ...
Tóm tắt. Kim loại nặng trong trầm tích tác động bất lợi cho sinh vật đáy. Những tác động đó hiếm khi có thể được dự đoán từ tổng nồng độ kim loại do ảnh hưởng của các dạng tồn tại trong trầm tích là khác nhau. Để đánh giá bất lợi tiềm ẩn do chất ô nhiễm Cu, Pb trong trầm tích, mô hình thử nghiêm độc tính dung dịch lắng trầm tích bổ sung (Cu 2+ , Pb 2+) lên phôi, ấu trùng hàu Crassostrea gigas đã được thực hiện. Mô hình được thực hiện theo 3 giai đoạn: (i) Điều chế mẫu trầm tích được thêm chuấn (Cu 2+ , Pb 2+); (ii) Điều chế các dung dịch lắng từ các mẫu trầm tích đã thêm chuẩn (Cu 2+ , Pb 2+) và (iii) Thử nghiệm độc tính phôi, ấu trùng Crassostrea gigas bằng dung dịch lắng. Các thông số như tỉ lệ thụ tinh, tỉ lệ bất thường của phôi, ấu trùng và EC50 được xác định. Kết quả cho thấy độc chất khi tiếp xúc với tinh trùng, trứng, cả tinh trùng và trứng cho EC50 là 0,024; 0,063; 0,034mg/L đối với Cu và 4,7; 14,0, 5,5 mg/L đối với Pb; Tỉ lệ ấu trùng không phát triển sau 24 giờ cho EC50 là 0,015 mg/L cho Cu và 2,88 mg/L cho Pb. Kết quả cho thấy độc tính Cu cao hơn Pb và trứng ít nhạy cảm hơn so với tinh trùng. Kết quả nghiên cứu có thể sử dụng để dự báo mức độ nhạy cảm của Cu, Pb trong trầm tích vùng cửa sông Soài Rạp lên phôi, ấu trùng hàu Crassostrea gigas. Từ khóa: Crassostrea gigas, Cu và Pb, độc tính, Sài Gòn-Đồng Nai, trầm tích. 1. GIỚI THIỆU Cửa sông Soài Rạp thuộc hệ thống sông Sài gòn-Đồng Nai đang chịu nhiều tác động của các hoạt động công nghiệp, đô thị hóa dẫn đến khả năng ô nhiễm cao, trong đó Cu, Pb là đáng quan ngại [1]. Đồng là một nguyên tố vi lượng cần thiết ở mức độ rất nhỏ cho các chức năng sinh học của các sinh vật [2]. Tuy nhiên, dư thừa đồng gây trở ngại với các chức năng sinh học quan trọng và tác động lên sự phát triển của phôi, khả năng thụ tinh của trứng và tinh trùng [3]. Chì là một kim loại nặng cực kỳ độc hại làm xáo trộn các quá trình sinh lý khác nhau và không giống như các kim loại khác, chẳng hạn như kẽm, đồng và mangan, vì nó có thể gây độc hại ở nồng độ rất thấp [4]. Tuy nhiên, sẽ rất khó khăn để có thể được dự đoán tác động tiềm ẩn từ tổng nồng độ kim loại vì nó bị ảnh hưởng bởi các dạng tồn tại của kim loại trong trầm tích cũng như hóa sinh, sinh lý và hành vi của sinh vật đáy [5]. Các thử nghiệm về độc tính các chất gây ô nhiễm kim loại trong trầm tích đã được sử dụng để đánh giá các rủi ro về môi trường. Thử nghiệm độc chất sử dụng dung dịch lắng trầm tích kết hợp kim loại nặng đã được thực hiện để minh chứng các tác động của chúng lên sinh vật đáy [6, 7]. Giai đoạn đầu đời (sự thụ tinh của trứng, tinh trùng và sự phát triển của ấu trùng) của động vật không xương nhạy cảm cao với các tác nhân ô nhiễm so với giai đoạn trưởng thành và do đó giai đoạn này thường được dùng để thử nghiệm đánh giá độc tính sinh học, trong đó, hàu Crassostrea gigas được công nhận là nhạy cảm [8, 9]. Nhiều thử nghiệm độc tính đã được thực hiện khi dung dịch lắng của trầm tích tiếp xúc phôi, ấu trùng hàu [6]. Dung dịch lắng được thu từ mẫu trầm tích bổ sung chuẩn được ngâm chiết với dung dịch lỏng theo một tỉ lệ, được làm đồng nhất, để lắng, dung dịch nằm trên được sử dụng trong thí nghiệm độc tính [10]. Một loạt mẫu dung dịch lắng với khoảng nồng độ chất ô nhiễm bổ sung với trầm tích sẽ được thử nghiệm, kết quả thử nghiệm là các thông số LC50; EC50 của hóa chất chuẩn bổ sung vào trầm tích được xác định. Đối với các thí nghiệm độc tính cho sinh vật 2 mảnh vỏ vùng cửa sông, dung dịch lỏng được thay bằng nước muối biển/trầm tích tỉ lệ là 4:1, thời gian cân bằng 12 giờ [11]. Mẫu trầm tích bổ sung chuẩn có thể được bổ sung một hoặc nhiều chất gây ô nhiễm cần quan tâm để tạo ra các kịch bản liên quan. Các đặc tính hấp phụ của trầm tích phải được khảo sát trước khi thực hiện điều chế trầm tích bổ sung chuẩn sao cho mẫu trầm tích
... The aquatic nontarget organisms are often used to conduct the toxicity testing of paddy field herbicides 22−24 because the paddy field itself is an aquatic system characterized with flooded shallow water environments 24 and herbicides applied in the system can enter the surrounding open water sources by surface runoff, spray drift, and leaching. 25,26 As the typical aquatic model organism, various life stages of zebrafish were widely used to conduct the toxicity test, such as adult fish, 27 embryo, 28 and larvae. 29,30 Recently, evaluating the toxicity of herbicides using the fish embryos has become a prevalent approach. ...
Pyraquinate, a newly developed 4-hydroxyphenylpyruvate dioxygenase class herbicide, has shown excellent control of resistant weeds in paddy fields. However, its environmental degradation products and corresponding ecotoxicological risks after field application remain ambiguous. In this study, we systematically investigate the photolytic behaviors of pyraquinate in aqueous solutions and in response to xenon lamp irradiation. The degradation follows first-order kinetics, and its rate depends on pH and the amount of organic matter. No vulnerability to light radiation is indicated. Ultrahigh-performance liquid chromatography with quadrupole-time-of-flight mass spectrometry and UNIFI software analysis reveals six photoproducts generated by methyl oxidation, demethylation, oxidative dechlorination, and ester hydrolysis. Gaussian calculation suggests that activities due to hydroxyl radicals or aquatic oxygen atoms caused these reactions on the premise of obeying thermodynamic criteria. Practical toxicity test results show that the toxicity of pyraquinate to zebrafish embryos is low but increases when the compound is combined with its photoproducts.
... Given it is found at elevated concentrations in oyster culture areas (Caquet et al., 2013). A genotoxic effect was recorded in hemocytes marked by DNA alteration (Barranger et al., 2014) as well as a reduction in fertility caused by a change in sperm quality (Mai et al., 2013). Previous studies also demonstrated that Diuron treatment caused the onset of oxidative stress via release of ROS in oyster embryos (Behrens et al., 2016). ...
Coastal marine systems are the most sensitive zones to emerging pollutants. The present study aims to investigate
the effect of Diuron on the meiofaunal assemblages, collected from the Bizerte channel (Tunisia). Microcosm
experiments were set up using four increasing Diuron concentrations [D1 (10 ng g 1 dry weight (DW)), D2 (50
ng g 1 DW), D3 (250 ng g 1 DW) and (1250 ng g 1 DW)] compared to non-contaminated sediments (controls)
and all plots were incubated for 30 days. Our results show that Diuron-supplemented sediments provoked the
significant decrease of meiofaunal abundance as well as a change in nematodes’ diversity and structure
composition. All univariate indices, as well as the cumulative k-dominance, were lower in the Diuron than the
control plot. Additionally, the ordination of treatments according to the two-dimensional nMDS plots analysis
showed a clear structural separation of the Diuron treated replicates from the controls based on the functional
groups lists. These current data emphasize the utility of the use of biological traits in the detection of disturbances
in the aquatic biotope
... Evidently, DCOIT is highly toxic to oyster embryos and could affect other bivalves in aquaculture; therefore, further research is warranted to identify these effects. The toxic concentrations of diuron and Irgarol for embryos are >1000 μg/L (24-h LC 10 , using larvae from adult oysters in Hiroshima Bay [Tsunemasa and Okamura 2011]), and 0.004 and 0.001 μg/L, respectively (24-h NOEC, using oyster larvae from a commercial hatchery [Mai et al. 2012[Mai et al. , 2013), based on nominal concentrations. The toxicity value of diuron is 0.002 μg/L (24 h NOEC, for oyster larvae from a commercial hatchery [Behrens et al. 2016]), based on nominal concentrations. ...
The Pacific oyster (Crassostrea gigas) is an important species in oyster farming worldwide, including in Japan. Hiroshima Bay is one of the most important oyster farming areas in Japan. We investigated the occurrence of antifouling biocides used worldwide including diuron, Irgarol 1051 (Irgarol), and 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one (DCOIT), which have been detected at sub-ppb levels in seawater in Japan, and estimated their no observed effect concentrations (NOECs). In recent years, the spat settlement of Pacific oysters has become poor, which presents a challenge for oyster aquaculture in Hiroshima Bay; hence, we conducted embryotoxicity and larva settlement tests using Pacific oysters. Compared to diuron and Irgarol, DCOIT exhibited a higher toxicity toward oyster embryos, and the minimum 24-h NOEC toxicity value for the oyster embryos was <3 ng/L. The highest concentrations of diuron, Irgarol, and DCOIT in the environmental seawater in the Seto Inland Sea were 27.6, 3.2, and 24 ng/L, respectively. Considering the NOECs, the environmental concentrations of these biocides suggest that the ecological risks posed by diuron and Irgarol are low, whereas those posed by DCOIT are high. However, the rate of detection of DCOIT was low because it degraded rapidly in the seawater before treatment for chemical analysis, except in the case of the treatment on the research vessel.
... Seawater quality is a main factor affecting fertilization and larval development 36 successes in these organisms (Havenhand et al., 2008). In particular, contaminants could 37 negatively affect their reproduction as demonstrated in oysters exposed to anthropogenic 38 pollutants (Akcha et al., 2012;Fitzpatrick et al., 2008;Mai et al., 2013;Vignier et al., 2017Vignier et al., , 39 2015. Experimental studies suggest that harmful algal blooms (HAB), often caused by 40 dinoflagellates, can affect marine bivalve reproduction by altering gamete quality and larval 41 development, growth, and survival (Banno et al., 2018;Basti et al., 2013Basti et al., , 2011Binzer et al., 42 2018;Bricelj and MacQuarrie, 2007;Castrec et al., 2020Castrec et al., , 2019De Rijcke et al., 2015;43 Gaillard et al., 2020;Rolton et al., 2018Rolton et al., , 2015Rolton et al., , 2014Tang and Gobler, 2012). ...
Dinoflagellates from the globally distributed genus Alexandrium are known to produce both paralytic shellfish toxins (PST) and uncharacterized bioactive extracellular compounds (BEC) with allelopathic, ichthyotoxic, hemolytic and cytotoxic activities. In France, blooms of Alexandrium minutum appear generally during the spawning period of most bivalves. These blooms could therefore alter gametes and/or larval development of bivalves, causing severe issues for ecologically and economically important species, such as the Pacific oyster Crassostrea (=Magallana) gigas. The aim of this work was to test the effects of three strains of A. minutum producing either only PST, only BEC, or both PST and BEC upon oyster gametes, and potential consequences on fertilization success. Oocytes and spermatozoa were exposed in vitro for 2 h to a range of environmentally realistic A. minutum concentrations (10-2.5 × 104 cells mL-1). Following exposure, gamete viability and reactive oxygen species (ROS) production were assessed by flow cytometry, spermatozoa motility and fertilization capacities of both spermatozoa and oocytes were analysed by microscopy. Viability and fertilization capacity of spermatozoa and oocytes were drastically reduced following exposure to 2.5 × 104 cells mL-1 of A. minutum. The BEC-producing strain was the most potent strain decreasing spermatozoa motility, increasing ROS production of oocytes, and decreasing fertilization, from the concentration of 2.5 × 103 cells mL-1. This study highlights the significant cellular toxicity of the BEC produced by A. minutum on oyster gametes. Physical contact between gametes and motile thecate A. minutum cells may also contribute to alter oyster gamete integrity. These results suggest that oyster gametes exposure to A. minutum blooms could affect oyster fertility and reproduction success.
... Impact of imidacloprid on molluscs were recently thoroughly reviewed (Ewere et al., 2021). Effects of the mentioned individual compounds on the embryo-larval stages of the Pacific oyster were already assessed (Gamain et al, , 2017Kuchovská et al., 2021;Mai et al, 2013Mai et al, , 2014, and some of these were even present in a recent complex mixture of 14 pesticides toxicity evaluation (Mai et al., 2020). ...
Worsened state of oysters in French Arcachon Bay, demand an investigation of possible causes. This study evaluated the effects of an environmentally relevant mixture of five common pesticides on the early-life stages of the Pacific oyster (Magallana gigas). Laboratory assays with artificial mixture and in situ transplantation were complementarily used to investigate a series of sublethal endpoints. The laboratory exposure revealed developmental toxicity at 0.32 μg/L, which corresponds to mixture concentrations in Arcachon Bay. Downregulation of some gene transcriptions was observed at environmental level. No difference in larvae development was revealed among the three sites in Arcachon Bay. This study was the first to evaluate locomotion of oyster larvae exposed in situ. Suspected poor water quality in the inner part of Arcachon Bay was reflected by impairment at the molecular level. In conclusion, current concentrations of the tested pesticides in Arcachon Bay hinder larval development and affect several biological functions.
... In freshwater environments, herbicides are environmental pollutants transmitted by surface runoff, spray drift, and leaching from agricultural areas (Battaglin et al., 2000). Herbicides that enter aquatic environments via leachate and runoff from agricultural areas can remain there for months or even years (Mai et al., 2013). In modern agriculture, selective herbicides are mainly used to protect economically beneficial crops and effectively remove weeds and therefore have low toxicity to non-target organisms (Riechers et al., 2010). ...
Excessively used pesticides in agricultural areas are spilled into aquatic environments, wherein they are suspended or sedimented. Owing to climate change, herbicides are the fastest growing sector of the pesticide industry and are detected in surface water, groundwater, and sediments near agricultural areas. In freshwater, organisms, including mussels, snails, frogs, and fish, are exposed to various types and concentrations of herbicides. Invertebrates are sensitive to herbicide exposure because their defense systems are incomplete. At the top of the food chain in freshwater ecosystems, fish show high bioaccumulation of herbicides. Herbicide exposure causes reproductive toxicity and population declines in freshwater organisms and further contamination of fish used for consumption poses a risk to human health. In addition, it is important to understand how environmental factors are physiologically processed and assess their impacts on reproductive parameters, such as gonadosomatic index and steroid hormone levels. Zebrafish is a good model for examining the effects of herbicides such as atrazine and glyphosate on embryonic development in freshwater fish. This review describes the occurrence and role of herbicides in freshwater environments and their potential implications for the reproduction and embryonic development of freshwater organisms.
... A concentration of 0.14 μg.L −1 of chlortoluron was detected in 2018, at the mouth of the Charente (Pertuis Charentais), close to oyster farms (Action program, 2018). The herbicide family has already been studied in oysters, showing effects at the early stages of development on survival and development (Mottier et al., 2013;Gamain et al., 2017;Behrens et al., 2016;Mai et al., 2013), during gametogenesis with genotoxic effects , as well as by modulating molecular and biochemical parameters . ...
Nowadays, pesticides and microplastics (MPs) are commonly found in coastal waters worldwide. Due to their widespread use, their persistence and toxicity, they may induce adverse effects on physiology and behaviour of marine organisms such as the Pacific oyster (Crassostrea gigas). This study explored the growth and valve activity of juvenile oysters exposed for 24 days to two frequently detected pollutants in the Pertuis Charentais (South West, France): a herbicide (chlortoluron, 85 µg.L⁻¹) and high-density polyethylene microparticles (HDPE 20-25 µm, 112 MP.mL⁻¹) alone or in combination (cocktail condition; 97 µg.L⁻¹ of chlortoluron + 108 MP. mL⁻¹). The valve activity of juvenile oysters recorded by using a High Frequency and Non-Invasive valvometer (HFNI) was characterized by three parameters: the number of valve micro-closures (VMC), the Valve Opening Amplitude (VOA), and the Valve Opening Duration (VOD). Additionally, daily shell growth and the oyster daily rhythm were assessed. The exposure to MPs of oysters led to a significant increase of VMC and a decrease of VOD and shell growth. The exposure to chlortoluron showed a significant increase of VOA and a decrease of VMC. In combination with MPs, chlortoluron still increased VOA and decreased VMC but also reduced the shell growth. Chronobiological analysis did not reveal any effects on the daily rhythm of both contaminants. This work highlighted significant effects of high environmental concentrations of MPs and Chlortoluron on the behaviour and growth of the Pacific oyster.
... The chemical nature and "quality" of the seawater into which gametes are released therefore plays a key role in fertilization and larval development (Havenhand et al., 2008). Previous studies have shown that acute exposure of spermatozoa and oocytes to organic pollutants (Akcha et al., 2012;Mai et al., 2013;Vignier et al., 2017Vignier et al., , 2015 or to copper (Fitzpatrick et al., 2008) could negatively affect fertilization success and embryo development of oysters. ...
Les dernières décennies ont été marquées par l’intensification et l’expansion des efflorescences de micro-algues toxiques (HAB). Connues pour perturber les écosystèmes côtiers et pour leur toxicité sur les organismes marins, les HAB sont suspectées d’être à l’origine de défauts de recrutement de bivalves. Cette thèse avait pour objectif d’étudier les conséquences des efflorescences du dinoflagellé toxique Alexandrium minutum, producteur de toxines paralysantes (PST) et des composés bioactifs extracellulaires (BEC), sur la reproduction, le développement et le recrutement de l’huître Crassostrea gigas, une espèce à l’importance économique majeure. Les gamètes libres et les jeunes stades de développement se révèlent être les plus sensibles, en particulier aux BEC produits par A. minutum qui inhibent la fécondation et l’embryogenèse. A. minutum modifie le comportement des larves véligères, provoque une diminution de leur filtration, de leur croissance et du taux de fixation. Une exposition des adultes, pendant la gamétogenèse, affecte le développement des descendants, traduisant des altérations du contenu gamétique et/ou un transfert vertical des PST. Les modalités d’action des PST et des BEC devront être précisées. Nos expérimentations, réalisées à des concentrations de micro-algues rencontrées dans l’environnement, suggèrent que des efflorescences récurrentes d’A. minutum lors des périodes de reproduction et de développement larvaire pourraient, sur le long terme, affecter la structure des populations naturelles et cultivées de C. gigas.
... DNA fragmentation was also detected in sperm of exposed male genitors, such as the presence of the oxidative DNA lesion 8-oxodGuo in the germ cells from both sexes . In oyster embryos, diuron was responsible for DNA strand breaks; genotoxicity was proposed to be one of the probable molecular events involved in its embryotoxicity (Akcha et al. 2012;Mai et al. 2013;Behrens et al. 2016;Sussarellu et al. 2018). DNA strand breaks and 8-oxodGuo are oxidative DNA lesions that are thought to be produced during the oxidative stress occurring following diuron exposure. ...
Recently, research has contributed to better knowledge on the occurrence of pesticides in coastal water by identifying frequently detected substances, their concentration range and their acute and chronic toxicity for organisms. Pesticide pollution is of particular concern in France due to important agricultural activities and presence of several exoreic catchment areas that vehicle pesticides up to coastal waters, impacting non-target marine species. Several ecotoxicology questions remain to be addressed concerning the long-term effects of chronic pesticide exposure and the mechanisms involved in adaptation to chemical stress. In the present study, we brought new insights on the genetic and epigenetic effects of the herbicide diuron in oyster genitors. During gametogenesis, we exposed Crassostrea gigas to environmentally realistic herbicide concentrations (0.2–0.3 μg L⁻¹ during two 7-day periods at half-course and end of gametogenesis). Diuron exposure was shown to decrease global DNA methylation and total methyltransferase activity in whole oyster tissue; this is consistent with the previous observation of a significant decrease in DNMT1 gene expression. Diuron effect seemed to be tissue-specific; hypermethylation was detected in the digestive gland, whereas diuron exposure had no effect on gill and gonad tissue. The genotoxicity of diuron was confirmed by the detection of one adduct in gonad DNA. By using in vitro approaches and human DNMT1 (DNMT1 has not been purified yet in bivalves), the presence of DNA lesions (adduct, 8-oxodGuo) was shown to interfere with DNMT1 activity, indicating a complex interaction between DNA damage and DNA methylation. Based on our results, we propose mechanisms to explain the effect of diuron exposure on DNA methylation, a widespread epigenetic mark.
... Oyster genitors were spawn by thermal stimulation (alternating immersion in 18 C and 28 C seawater for 30 min) or by stripping the gonad (Mai et al., 2013;Gamain et al., 2017). At the time of the gamete expulsion, spawning males and females were individually isolated in beakers with 0.2 mm FSW. ...
Plastics are persistent synthetic polymers that accumulate as waste in the marine environment. Microplastics (MPs, <5 mm) can be found either as microbeads in body care and some industrial products or as plastic debris through degradation. Plastic microbeads (1–5 μm, fluorescent, Cospheric) were used to characterise the MP ingestion and determine their potential harmful effects on both the swimming behaviour and development of oyster D-larvae (Crassostrea gigas). For 24 h, embryos were first exposed to MPs at a temperature of 24 °C. In addition, 3 day-old D-larvae were exposed to the same temperature for 1, 3 and 5 h. Three concentrations of MPs were used: 0.1, 1 and 10 mg MP. L⁻¹. After a 24-h period of embryonic exposure, we noted that MP agglomerates were stuck to the D-larvae coat and locomotor eyelashes. We also observed a significant increase in severe malformations and developmental arrests for larvae exposed to MPs ranging from 1 mg MP. L⁻¹. In terms of swimming behaviour, the maximum speed recorded was lower for larvae exposed at 0.1 and 1 mg MP. L⁻¹. After an acute exposure to MPs, particles were found in the digestive tract of 3 dpf (days post fertilisation) D-larvae. After 1-h exposure, the concentrations tested (0.1, 1 and 10 mg MP. L⁻¹) resulted in respectively 38%, 86% and 98%. The larvae swimming behaviour was recorded and analysed. Unlike the results observed at the embryo-larval stage, 3-dpf larvae showed significant impacts with no dose-response effect.
... Alterations on the activity of the aromatase enzyme might cause deficiencies in male reproduction. Mai et al. (2013) detected low success in fertilization and high defects in oyster embryo development with low doses of metolachlor. Furthermore, Zeilinger et al. (2009) found that acetochlor (acetamide-type herbicide) was able to alter the thyroid system of fish species at high concentrations. ...
Agriculture is one of the bases of worldwide economy. In recent decades, the use of genetically modified crops caused a continuous increase in pesticide and fertilizer application. In productive countries, the adoption of these products together with other technologies allowed the maximization of world crop production with great economic benefits. Herbicides represent about 40–60% of the total pesticides used in the agricultural environment. Several herbicides are used for control of weeds worldwide, glyphosate being one of the most common. The excessive use of this product has resulted in the emergence of tolerant weeds, thus a wider variety of herbicides are being used, such has clodinafop propargyl, atrazine, and 2,4 dichlorophenoxyacetic acid among others. Because of the potential negative effects of these chemicals on the soil ecosystem and public health, the application of herbicides has become a matter of great concern by the regulatory organisation. The extensive incorporation of herbicides in this ecosystem involves an important impact on the natural microbiota. Herbicides interact with target and non‐target organisms, so they could damage the ecosystem and also they can enter the food chain. Microbial degradation is the most frequent mechanism implied in the destruction of these contaminants. In this process, fungal species have a great participation in xenobiotocs dissipation. They present propitiate metabolic characteristics in bioremediation due to their mycelia growth, rapid colonization of solid substrates and enzymatic capacity. In addition, these microorganisms have a great tolerance to pollutants and unfavorable environmental conditions. Fungal genera such as Cladosporium spp., Fusarium spp., Mucor spp., Penicillium spp., Aspergillus spp., Trichoderma spp., and Saccharomyces spp. have shown the ability to degrade herbicides. They are capable of producing several hydrolytic enzymes during their development, resulting in significant pesticides disipation rates. Recently, this aspect has focused on the development of harmless bioremediation strategies. The present chapter presents information about the toxicity of the main herbicides used in agriculture and also about the tolerance and degradation of them by fungal species.
... Some of them, including Irgarol® 1501 and diuron, act as herbicides/pesticides and are used in conjunction with copper-based antifouling (AF) agents. However, several studies have shown that these compounds are also toxic to marine ecosystems and nonfouling marine organisms (Okamura et al., 2000;Owen et al., 2002;Negri et al., 2005;Thomas and Brooks, 2010;Bao et al., 2011;Mai et al., 2013;Jung et al., 2017;Carvalhal et al., 2018). Therefore, the development of new environmentally friendly alternatives to these treatments is of great importance. ...
Marine biofouling represents a global economic and ecological challenge. Some marine organisms produce bioactive metabolites, such as steroids, that inhibit the settlement and growth of fouling organisms. The aim of this work was to explore bile acids as a new scaffold with antifouling (AF) activity by using chemical synthesis to produce a series of bile acid derivatives with optimized AF performance and understand their structure-activity relationships. Seven bile acid derivatives were successfully synthesized in moderate to high yields, and their structures were elucidated through spectroscopic methods. Their AF activities were tested against both macro-and microfouling communities. The most potent bile acid against the settlement of Mytilus galloprovincialis larvae was the methyl ester derivative of cholic acid (10), which showed an EC 50 of 3.7 μM and an LC 50 /EC 50 > 50 (LC 50 > 200 μM) in AF effectiveness vs toxicity studies. Two derivatives of deoxycholic acid (5 and 7) potently inhibited the growth of biofilm-forming marine bacteria with EC 50 values < 10 μM, and five bile acids (1, 5, and 7-9) potently inhibited the growth of diatoms, showing EC 50 values between 3 and 10 μM. Promising AF profiles were achieved with some of the synthesized bile acids by combining antimacrofouling and antimicrofouling activities. Initial studies on the incorporation of one of these promising bile acid derivatives in polymeric coatings, such as a marine paint, demonstrated the ability of these compounds to generate coatings with anti-macrofouling activity.
... The toxicity of such substances was investigated on a wide range of organisms (Akcha et al., 2012;Ali et al., 2015;Barranger et al., 2014;Cardoso et al., 2013;Katsumata and Takeuchi, 2017;Mai et al., 2013;Moreira et al., 2018;Pereira et al., 2015;Zhang et al., 2019). However, limited information is available on the presence of those compounds in sediments and porewaters, and a study focusing on the occurrence and behavior of antifouling biocides in both matrices simultaneously, as far as we know, is inexistent in South America. ...
Fouling organisms attach and grow on submerged surfaces causing several economic losses. Thus, biocides have been introduced in antifouling paints in order to avoid this phenomenon, but their widespread use became a global problem, mainly in ports, leisure and fishing boat harbors, since these substances can be highly toxic to non-target organisms. The occurrence and environmental behavior of antifouling biocides are especially unknown in some peculiar regions, such as Amazon areas. Thus, the aim of this work was to evaluate, for the first time, levels and the partitioning behavior of the antifouling organic biocides irgarol, diuron and also stable degradation products of dichlofluanid and diuron (DMSA and DCPMU, respectively) in sediments and porewaters from a high boat traffic area located in the Northeast of Brazil, a pre-Amazon region. Our results showed high concentrations of irgarol (<1.0-89.7 μg kg-1) and diuron (<5.0-55.2 μg kg-1) in sediments. In porewater, DCPMU (<0.03-0.67 μg L-1) and DMSA (<0.008-0.263 μg L-1) were the mainly substances detected. High Kd and Koc obtained for both irgarol and diuron showed a partitioning preference in the solid phase. This work represents one of the few registers of contamination by antifouling substances in Amazonian areas, despite their environmental relevance.
... The presence of potentially toxic species in the river may lead to the release of genotoxic cyanotoxins, thus creating a genotoxicological environment, formed by the mixture of heavy metals, cyanotoxins and other contaminants released by the anthropogenic activities. The aromatic and polycyclic hydrocarbons (PHAs) and organochlorine compounds, although not studied in our present study, are normally released and are frequent in aquatic environments suffering from the human activities from industrial, agricultural and domestic effluents, may also be involved in the cytotoxic and mutagenic effects in the aquatic environment (Di Giorgio et al. 2011;Mai et al. 2013). Therefore, organisms exposed to this type of environment may fall in difficulty in cell division, suffer by genetic and/or chromosomal mutations at the cellular level, as well as reproductive failure and, consequently, their existence in the aquatic system (Farmer and Singh 2008;Leme and Marin-Morales 2009). ...
Tropical rivers used for water supply, irrigation and tourism have effects on anthropic activities. This study aimed to evaluate the presence of different pollutants in the aquatic environment of the Guaribas river water and their possible cytogenotoxic effects. For this, the presence of heavy metals and cyanobacteria along with the possible cytogenotoxic effects in the aquatic environment were evaluated at the city of Picos-PI/Brazil, of its upstream, within and downstream regions. The results suggest that the electrical conductivity, total dissolved oxygen and solids, turbidity, color, chlorine and total phosphorus were above the allowed levels by the country’s legislation, especially at the points associated with the main city. Water collected from the within and downstream regions showed a significant cytotoxic and mutagenic effects, regardless of seasons, where a positive correlation was observed between the genetic damage and heavy metal contents. Furthermore, mutagenic cyanotoxins were also found in the samples. These results pointed out that the Guaribas river contains physical and chemical contaminants, and cyanotoxins, that can cause genetic damages, suggesting a bad impact on the aquatic ecosystem, human and other animals directly or indirectly dependent on it. In conclusion, adequate attention is required to establish toxicogenic biomonitoring programs for the other tropical rivers in Brazil.
... The toxicity of copper and S-metolachlor for early life stage of aquatic species is well-documented. It has been shown that both compounds induced significant developmental anomalies and DNA damage in bivalves at environmentally realistic concentrations (Mai et al. 2012(Mai et al. , 2013Gamain et al. 2017a). Behavior is an integrated and whole-organism response (Faimali et al. 2017). ...
This study describes an image analysis method that has been used to analyze the swimming behavior of native oyster D-larvae (Crassostrea gigas) from the Arcachon Bay (SW, France). In a second time, this study evaluated the impact of copper and S-metolachlor pollutants on D-larvae swimming activity and the possible relationship between developmental malformations and abnormal swimming behavior. Analyses in wild and cultivated oyster D-larvae were investigated during two breeding-seasons (2014 and 2015) at different sampling sites and dates. In controlled conditions, the average speed of larvae was 144 μm s⁻¹ and the maximum speed was 297 μm s⁻¹ while the trajectory is mainly rectilinear. In the presence of environmental concentration of copper or S-metolachlor, no significant difference in maximum or average larval speed was observed compared to the control condition but the percentage of circular trajectory increased significantly while the rectilinear swimming larvae significantly declined. The current study demonstrates that rectilinear trajectories are positively correlated to normal larvae while larvae with shell anomalies are positively correlated to circular trajectories. This abnormal behavior could affect the survival and spread of larvae, and consequently, the recruitment and colonization of new habitats.
... The spat or postlarva is the prime material for cultivation activities and normally is obtained from the natural environment using collectors placed in strategic places during the spawning season (Robert & Gérard, 1999). Nevertheless, spat collection is affected by diverse factors as extreme environmental conditions, pollution, low yields or absence of natural collection in some regions (Mai et al., 2013;Neto et al., 2013). In these cases, oyster farmers obtain the spat from certified hatcheries, which replicate the reproductive cycle of the species under controlled conditions (Chávez -Villalba, 2014). ...
Production protocols as well as the origin of broodstock in hatcheries are the important factors determining the attributes of Crassostrea gigas oyster spat. Spat from diverse hatcheries may have different attributes for commercial activities. We described the biological performance (growth and condition index – CI) of spat stocks produced at different hatcheries (H1, H2, H3 and H4), and simultaneously cultivated in La Cruz lagoon (Mexico). Analysis of pathogens and genetic variability was performed for each stock. Temperature, salinity, chlorophyll a and seston were measured during samplings. Stocks showed similar growth patterns but each one showed a distinctive curve. Temperature was the governing factor on growth but its effect was variable depending on the stock and whether the temperature increases, stays high or decreases. Availability of food was high producing elevated CI. No presence of pathogens was detected and it was not possible to obtain amplicons of the mitochondrial regions. Despite differences in performance among stocks, all of them showed higher values (growth rates, CI, survival) than the standards reported for the Gulf of California. These findings are useful for the production and cultivation of C. gigas, but more studies are needed to understand the influence of hatchery protocols on spat quality.
... S-Metolachlor is classified as inhibitor of very-long-chain fatty acid formation and can be extremely toxic to fish and aquatic species [5,6]. According to the World Health Organization (WHO) regulation, the maximum allowable concentration in drinking water is 0.01 mg/L. ...
The adsorption of S-metolachlor herbicide from aqueous solution by benzenesilica materials was studied. The materials were synthesized with 1,4-bis(triethoxysilyl)benzene as organosilica precursor and Brij 76 and Pluronic P123 as surfactants. Additionally, 1,3,5-triisopropylbenzene (TPB) was used as porogen to produce microporosity. Those materials obtained by Brij-76 and P123 showed well-structured ordering. However, a disordered microporous benzenesilica material was obtained in presence of P123 and TPB. All materials proved to be efficient adsorbents for S-metolachlor. Among them, the material synthesized with Brij 76 showed the highest adsorption capacity due to its ordered structure and, mainly, to its higher proportion of mesopores.
... Its large usage and relatively low adsorption in soil cause a considerable discharge into groundwater, thus compromising water quality [5]. Although ST is classified as moderately toxic (Class III) [4,6], its negative impact on aquatic microorganisms like phytoplankton [7], fish [8] and crustaceans [9], as well as on certain types of human cells [10] has been reported. Several authors have investigated the performance of various methods to treat water containing this and other herbicides. ...
... The environmental fate and behavior of Irg (Thomas et al., 2001;Sakkas et al., 2006) and its transformation in biological wastewater treatments (Luft et al., 2013) have been reviewed. Recent studies report on hazard and risk of Irg and related biocides for marine microalgae and other marine organisms (Dupraz et al., 2016;Sjollema et al., 2014;Mai et al., 2013). It was recently concluded that the environmental effect of Irgarol 1051 has not yet been fully assessed (Amara et al., 2018). ...
The herbicide 2-(methylthio)-4-(tert-butylamino)-6-(cyclopropylamino)-s-triazine (tradename Irgarol 1051, abbreviated here as Irg), widely used in antifouling paints as biocide inhibiting seaweeds growth, is found in coastal waters in the vicinity of ports and harbors. In this work, Irg was subjected to air non-thermal plasma (NTP) treatment, alone and in the presence of TiO2. A dielectric barrier discharge reactor was used, powered by AC voltage (18 kV, 50 Hz) to produce air-NTP directly above the surface of the aqueous Irg solution to be treated. Due to the very fast degradation of Irg occurring under the experimental conditions used, the results of kinetic experiments failed to detect any rate enhancement due to titania induced photodegradation. We show, however, that pre-adsorption of Irg on titania provides a means to significantly increase Irg NTP-induced degradation throughput, a result which might have useful practical consequences. It is concluded that this phenomenon is due to the acidic character of TiO2 which brings more Irg in solution by increasing the value of the ionization ratio, [IrgH+]/[Irg]. Product analysis, performed by LC/ESI-MSn, allowed us to detect and identify numerous intermediates of Irg degradation and to propose different competing reaction pathways for the investigated NTP induced Irg advanced oxidation process. The extent of mineralization to CO2 was assessed by Total Carbon analysis. It was found to reach 95% after 5 h treatment of Irg solutions with an initial concentration of 5·10-6 M. These results confirm the capability of our NTP prototype reactor to mineralize persistent organic pollutants.
... The mode of action of irgarol is similar to other triazine herbicides, in that it blocks electron transport during photosynthesis by inhibiting the energy transfer of photosystem II (PSII), reducing both CO 2 uptake and carbohydrate production, which causes the starvation of the plant (Ebert et al., 1976). The toxicity of irgarol in estuarine and marine organisms is well documented in the literature and most studies have focused on acute and chronic effects endpoints in bioassays for algae, invertebrates and fish (Konstantinou and Albanis, 2004;Bao et al., 2011;Castro et al., 2011;Perina et al., 2011;Mai et al., 2013). However, studies on sub lethal effects are limited with one study showing immunosuppression in the ascidian Botryllus schlosseri (Cima and Ballarin, 2012) and changes in the fatty acid composition of Asian sea-bass Lates calcarifer (Ali et al., 2015). ...
The triazine-based herbicide irgarol is widely used in antifouling systems as an algicide and has been detected recently in multiple coastal environments. Studies evaluating sub-lethal responses of fish following exposure to irgarol are limited. Moreover, impacts of climate change on fish endocrinology may also contribute to the sublethal toxicity of irgarol. We assessed the effects of irgarol on thyroid endpoints in juveniles of Menidia beryllina under two different treatments of salinity (10 and 20 ‰) and two temperatures (10 and 20°C). Condition factor coefficients (K) of animals were significantly affected by 0.1 to 10 μg/L of irgarol at the higher temperature. Levels of T3 were changed in whole body homogenates from both temperatures at 10‰ following exposure to 1 to 10 μg/L. T4 levels were altered only at 10°C when animals were treated with 1 to 10 μg/L (10 ‰), and in 0.1 and 10 μg/L (20 ‰). Increased transcripts of deiodinase enzymes at 10 °C may be impacted by salinity and alter thyroid hormone homeostasis. Impact on gene expression of thyroid (α and β) and growth hormone receptors were also determined. Our results highlight the relevance of environmental variable that may impact the ecological risk of irgarol in estuarine systems
Acetochlor (ACT) is a widely used pesticide, yet the environmental and health safety of its chiral isomers remains inadequately evaluated. In this study, we evaluated the toxicity of ACT and its chiral isomers in a zebrafish model. Our findings demonstrate that ACT and its chiral isomers disrupt early zebrafish embryo development, inducing oxidative stress, abnormal lipid metabolism, and apoptosis. Additionally, ACT and its chiral isomers lead to cardiovascular damage, including reduced heart rate, decreased red blood cell (RBC) flow rate, and vascular damage. We further observed that (+)-S-ACT has a significant impact on the transcription of genes involved in cardiac and vascular development, including tbx5, hand2, nkx2.5, gata4, vegfa, dll4, cdh5, and vegfc. Our study highlights the potential risk posed by different conformations of chiral isomeric pesticides and raises concerns regarding their impact on human health. Overall, our results suggest that the chiral isomers of ACT induce developmental defects and cardiovascular toxicity in zebrafish, with (+)-S-ACT being considerably more toxic to zebrafish than (-)-R-ACT.
To help meet objectives of the Great Lakes Restoration Initiative with regard to increasing knowledge about toxic substances, 223 pesticides and pesticide transformation products were monitored in 15 Great Lakes tributaries using polar organic chemical integrative samplers (POCIS). A screening‐level assessment of their potential for biological effects was conducted by computing toxicity quotients (TQs) for chemicals with available U.S. Environmental Protection Agency (EPA) Aquatic Life Benchmark values. Additionally, Exposure Activity Ratios (EAR) were calculated using information from the EPA ToxCast database. Between 16 and 81 chemicals were detected per site, with 97 unique compounds detected overall, for which 64 could be assessed using TQs or EARs. Ten chemicals exceeded TQ or EAR levels of concern at two or more sites. Chemicals exceeding thresholds included seven herbicides (2,4‐dichlorophenoxyacetic acid, diuron, metolachlor, acetochlor, atrazine, simazine, and sulfentrazone), a transformation product (deisopropylatrazine), and two insecticides (fipronil and imidacloprid). Watersheds draining agricultural and urban areas had more detections and higher concentrations of pesticides compared to other land uses. Chemical mixtures analysis for ToxCast assays associated with common modes of action defined by gene targets and adverse outcome pathways (AOP) indicated potential activity on biological pathways related to a range of cellular processes including, xenobiotic metabolism, extracellular signaling, endocrine function, and protection against oxidative stress. Use of gene ontology databases and the AOP knowledgebase within the R‐package ToxMixtures highlighted the utility of ToxCast data for identifying and evaluating potential biological effects and adverse outcomes of chemicals and mixtures. Results have provided a list of high priority chemicals for future monitoring and potential biological effects warranting further evaluation in laboratory and field environments. This article is protected by copyright. All rights reserved. Environ Toxicol Chem 2022;00:0–0.
The harmful effects of pesticides can be extended beyond the exposure time scale. Appraisals combining exposure and long‐term post‐exposure periods appear as an unavoidable approach in pesticide risk assessment, thus allowing a better understanding of the real impact of agrochemicals in non‐target organisms. This study aimed to evaluate the progression of genetic damage in somatic and germ tissues of the crayfish Procambarus clarkii, also seeking for gender‐specificities, following exposure (7 days) to penoxsulam (23 μg·L‐1) and a post‐exposure (70 days) period. The same approach was applied to the model genotoxicant ethyl methanesulfonate (EMS; 5 mg·L‐1) as a complementary mean to improve knowledge on genotoxicity dynamics (induction vs. recovery). Penoxsulam induced DNA damage in all tested tissues, disclosing tissue‐ and gender‐specificities, where females showed to be more vulnerable than males in the gills, while males demonstrated higher susceptibility in what concerns internal organs, i.e., hepatopancreas and gonad. Crayfish were unable to recover from the DNA damage induced by EMS in gills and hepatopancreas (both genders) as well as in spermatozoa. The genotoxicity in the hepatopancreas was only perceptible in the post‐exposure period. Oxidative DNA lesions were identified in hepatopancreas and spermatozoa of EMS‐exposed crayfish. The spermatozoa proved to be the most vulnerable cell type. It became clear that the characterization of the genotoxic hazard of a given agent must integrate a complete set of information, addressing different types of DNA damage, tissue‐ and gender‐specificities, as well as a long‐term appraisal of temporal progression of damage.
This study focused on the impacts of aged aquaculture microplastics (MPs) on oysters (Crassostrea gigas). Adult oysters were exposed for two months to a cocktail of MPs representative of the contamination of the Pertuis Charentais area (Bay of Biscay, France) and issuing from oyster framing material. The MPs mixture included 28% of polyethylene, 40% of polypropylene and 32% of PVC (polyvinyl chloride). During the exposure, tissues were sampled for various analyzes (MP quantification, toxicity biomarkers). Although no effect on the growth of adult oysters was noted, the mortality rate of bivalves exposed to MPs (0.1 and 10 mg. L⁻¹ MP) increased significantly (respectively 13.3 and 23.3% of mortalities cumulative). On the one hand, the responses of biomarkers revealed impacts on oxidative stress, lipid peroxidation and environmental stress. At 56 days of exposure, significant increases were noted for Glutathione S-Transferase (GST, 10 mg. L⁻¹ MP), Malondialdehyde (MDA, 10 mg. L⁻¹ MP) and Laccase (LAC, 0.1 and 10 mg. L⁻¹ MP). No variations were observed for Superoxyde Dismutase (SOD). Besides, ingestion of MPs in oyster tissues and the presence in biodeposits was highlighted. In addition, in vitro fertilisations were performed to characterize MPs effects on the offspring. Swimming behavior, development and growth of D-larvae were analysed at 24-, 48- and 72-h after fertilisation. D-larvae, from exposed parents, demonstrated reduced locomotor activity. Developmental abnormalities and arrest as well as growth retardation were also noted. This study highlighted direct and intergenerational effects of MPs from aged plastic materials on Pacific oysters.
Pesticides have enabled humankind to protect its crops from pests, intensifying thus the crop yields to sustain the growing population. However, pesticides often end up in aquatic water bodies, e.g. via field runoff, where they may harm non-target organisms. The environmental concentrations of pesticides are often considered safe for aquatic ecosystems although they might induce sublethal changes in exposed organisms. Moreover, the organisms are generally not dealing with only one pesticide issued from a nearby field but with a complex mixture of various chemical compounds, interacting amongst themselves, and creating a toxic cocktail with unknown and hardly predictable impacts. These compounds, each with different environmental fate, eventually degrade and form more or less toxic and persistent metabolites aggravating the complexity of the mixtures.This dissertation thesis summarizes the state-of-the-art in pesticide mixture toxicity research and is composed of five research articles dealing with sublethal effects of selected pesticides on non-target aquatic species. Vulnerable embryo-larval stages of two model organisms: freshwater zebrafish (Danio rerio) and euryhaline bivalve Pacific oyster (Magallana gigas) were used to assess the sublethal toxicity of especially environmental concentrations (detected in selected European water bodies) of commonly used herbicide S metolachlor with its two metabolites metolachlor oxanilic acid and metolachlor ethanesulfonic acid, insecticide imidacloprid, and fungicide propiconazole, alone and in a mixture. A complementary in situ approach was carried out to evaluate a real impact on early-life stages of the Pacific oyster in Arcachon Bay in France, a final recipient of various substances including pesticides from respective watersheds.First, zebrafish embryo-larval stages were observed to be highly sensitive to environmentally relevant concentrations of propiconazole and to a lesser extent also to imidacloprid. In contrast, S-metolachlor and its metabolites had almost no effect on their development, neurobehavioral functions, or gene expression except for altered genes implicated in the thyroid system. A mixture of these compounds exhibited a concentration addition effect on zebrafish development. These observations imply that the development of freshwater fish may be at risk with current agricultural practice.Second, a study with Pacific oyster embryos and larvae revealed very low toxicity of propiconazole and imidacloprid on their development and locomotion patterns. Few effects caused by these compounds were observed at the molecular level, as well as the effects caused by the mixture. The environmental concentration of the mixture induced developmental malformations in oyster larvae, however, those exposed in situ in Arcachon Bay did not show higher proportions of abnormal larvae suggesting that the water quality of Arcachon Bay is sufficient for oyster development. Nevertheless, oyster larvae exposed in the inner part of Arcachon Bay showed different gene expression levels than larvae from the reference site located near the ocean entrance, which may indicate consequences of a potential long term impact.These results documented that embryo-larval stages of zebrafish and Pacific oysters are relevant tools for the assessment of low concentrations of pesticides and pesticides in a mixture, and that laboratory studies complemented with field research are useful for (eco)toxicity assessment and of high ecological relevance.
In aquaculture, biocidal products such as disinfectants and antifoulants are used for minimizing the growth and settlement of fouling organisms in fish/shellfish tanks, fishnets, and other structures. Biocidal products are also used for water hygiene and to protect farmed animals from getting diseases. Nevertheless, those compounds are toxic and can be harmful to nontarget organisms, including farmed animals. In this chapter, the main disinfectants and organic antifouling co-biocides that are currently used in aquaculture, as well as their modes of action to prevent infections and fouling, are described. Additionally, toxic thresholds and deleterious biological effects associated with the use of biocidal products to nontarget organisms, including farmed animals, are outlined. The chapter ends with some current regulatory aspects governing the use of these products.
Coastal areas are final recipients of various contaminants including pesticides. The effects of pesticides on non-target organisms are often unclear, especially at environmentally relevant concentrations. This study investigated the impacts of insecticide imidacloprid (IMI) and fungicide propiconazole (PRO), some of the most detected pesticides in the Arcachon Bay in France. This work also included the research of propiconazole nanoformulation (nanoPRO). The effects were assessed studying the development of the early life stages of the Pacific oyster (Magallana gigas). Oyster embryos were exposed for 24, 30, and 42 h (depending on the endpoint) at 24 °C to environmentally relevant concentrations of the two pesticides as well as to nanoPRO. The research focused on sublethal endpoints such as the presence of developmental malformations, alterations of locomotion patterns, or changes in the gene expression levels. No developmental abnormalities were observed after exposure to environmental concentrations detected in the Arcachon Bay in recent years (maximal detected concentration of IMI and PRO were 174 ng/L and 29 ng/L, respectively). EC50 of PRO and nanoPRO were comparable, 2.93 ± 1.35 and 2.26 ± 1.36 mg/L, while EC50 of IMI exceeded 200 mg/L. IMI did not affect larval behavior. PRO affected larval movement trajectory and decreased average larvae swimming speed (2 μg/L), while nanoPRO increased the maximal larvae swimming speed (0.02 μg/L). PRO upregulated especially genes linked to reactive oxygen species (ROS) production and detoxification. NanoPRO effects on gene expression were less pronounced - half of the genes were altered in comparison with PRO. IMI induced a strong dose-response impact on the genes linked to the detoxification, ROS production, cell cycle, and apoptosis regulation. In conclusion, our results suggest that current pesticide concentrations detected in the Arcachon Bay are safe for the Pacific oyster early development, but they might have a small direct effect via altered gene expressions, whose longer-term impacts cannot be ruled out.
Environmental pollution due to anthropogenic activities may exert an adverse impact on the reproductive mechanisms of animals. Pollutants introduced into seawater are able to disrupt the normal development and function of the reproductive system of marine animals. Over the past two decades, biomarkers, i.e. parameters that reflect pollutant effects at molecular, cellular, organ, and organism level, have been increasingly used within environmental monitoring programs to provide information on the adverse effects of contaminants on biota. It has been argued that a useful biomarker should be ecologically relevant, in that it is reflective of effects at higher levels of organization, for example at the population level. Reproductive success can directly influence future generations and is therefore an ecologically relevant endpoint. Invertebrates constitute 95% of all animal species in natural ecosystems and current evidence suggests that marine invertebrates are particularly vulnerable to environmental disruptors. Data reported here show that most toxicity assessments may rely on marine invertebrate models and that reproductive processes may be considered an emerging biomarker acting as prognostic tool for an efficient assessment of the ecological marine hazard process.
Understanding the effects of plastic debris on marine ecosystems is essential in encouraging decision-makers to take action. The present study investigates the effect of a 24 h experimental exposure to high density polyethylene (HDPE) microplastics (MPs) of different sizes (4-6, 11-13 and 20-25 μm) and at three concentrations (0.1, 1 and 10 mg MP.L-1) on the development and locomotor activity of early stages of Pacific oyster, Crassostrea gigas. The bivalve embryo-larval assay (NF ISO 17244, 2015) was used in this study but with additional toxicity criteria: developmental arrests, abnormal D-larvae, maximum speed and swimming trajectory. Copper (Cu), was used as a positive control. Our results show that smaller MPs (4-6 and 11-13 μm) induced higher rates of malformations and developmental arrests than the larger ones (20-25 μm). In addition, a dose-dependent decrease of maximum swimming speed was observed for larvae exposed to MPs of 4-6 and 11-13 μm. On the other hand, there was no significant difference in swimming speed with the largest MPs size tested (20-25 μm). For all three sizes of MPs, there was a decrease in straight-line swimming trajectories, and an increase in circular trajectories. This abnormal swimming behaviour could affect larvae survival as well as colonization of new habitats.
Spermio- and embryotoxicities of Cu, Ag, Cd, and Hg were investigated in Paracentrotus lividus, the dominant echinoid species of the Mediterranean. Spermiotoxicity was studied by assessing the effects of sperm exposure on fertilization rate (FR) as well as on the induction of transmissible damages to the offspring. Embryotoxicity was studied by assessing developmental defects in larvae exposed to the tested metals throughout their development. Sperm exposures resulted in significant decreases of FR, depending on both metal concentration and duration of the exposure. Lowest spermiotoxic concentrations recorded when sperm were exposed for 75 min to the metals were 10{sup {minus}7} M Hg(II), 10{sup {minus}6} M Ag(I), 10{sup {minus}5} M Cu(II), and 10{sup {minus}5} M Cd(II). Tested metals did not exert any transmissible damage to spermatozoa that could result in larval malformations in the offspring, even for concentrations that dramatically reduced FR. Single-element exposures of embryos for 72 h resulted in developmental defects whose occurrence and severity showed a steep dose dependence, indicating that once a threshold is reached, any further increase in toxicant concentration rapidly enhances the impairment of target function(s). Those observations suggest the involvement of a saturable protective mechanism. Lowest observed embryotoxic concentrations of the metals were 10{sup {minus}7} M Hg(II), 2.5 {times} 10{sup {minus}7} M Ag(I), 5 {times} 10{sup {minus}7} M Cu(II), and 10{sup {minus}5} M Cd(II) and are in the range of concentrations reported in heavily polluted marine environments. Thus, the possibility of impairment of echinoid development actually exists in metal-contaminated marine environments, possibly threatening echinoid populations in those environments.
The effects of mercury (Hg) concentrations ranging from 0 (control) to 1024 mug l-1 upon embryogenesis, survival, growth and metamorphosis of Crassostrea gigas (Thunberg) oyster larvae were investigated. Embryogenesis was abnormal in 50% of the individuals at 11 mug l-1. The 48 h LD50 for D-shaped, umbonate and pediveliger larvae were 33, 115 and 200 mug l-1 respectively. The increase in LD50 was partially explained by the larval weight increase, although weight-specific tolerance to Hg was higher in smaller larvae. Growth, the most sensitive physiological process studied, was significantly retarded at 4 mug l-1. The metamorphosis rate was significantly reduced when competent pediveligers were exposed to 64 mug l-1 for 48 h prior to the addition of the metamorphosis inducer epinephrine. The implications of the present results for monitoring pollution by utilising different bivalve larval stages are discussed.
This study provides new information on the effects of various concentrations of the trace metals copper, lead, zinc, cadmium,
and nickel on fertilization success of gametes from the scleractinian reef corals Goniastrea aspera,Goniastrea retiformis, Acropora tenuis, and Acropora longicyathus. The EC50 values (the concentration that reduces the fertilization rate by 50% relative to the control fertilization) for
copper effects on fertilization success of these coral species range from 15 to 40µg/L, which is similar to responses of
other marine invertebrates. The EC50 values for lead were 1450–1800µg/L for the Acropora species, and >2400µg/L for G. aspera gametes, which indicates that lead was much less toxic than copper. Fertilization responses to zinc and nickel were variable
and a significant reduction in fertilization success for A. tenuis gametes was found only at very high cadmium concentrations. The data from this study and other recent research clearly demonstrate
that some trace metals impair the fertilization success of gametes from faviid and acroporiid reef corals. Trace metal inputs
into reef waters should be limited and controlled to avoid potential interference with sexual reproductive processes of reef
corals.
The gametes and embryos of three sea urchin species were exposed to cadmium chloride at concentrations ranging from 10(-8) M to 10(-3) M. When zygotes were reared in the presence of Cd2+, skeletal differentiation displayed some severe abnormalities or was suppressed, as a function of Cd2+ level. The embryotoxic action of Cd2+ was inversely related to salinity and to Ca2+ concentration. Cadmium-exposed larvae displayed similar abnormalities if Cd2+ was present throughout development or only after hatching, while pre-hatching exposure produced no developmental defects. No aberrations in mitotic figures were observed in cleaving eggs following acute exposure to Cd2+. The pretreatment of sperm or eggs did not affect the ensuing development of embryos, both for acutely toxic Cd2+ levels (up to 10(-2) M), and for prolonged exposures in relatively low Cd2+ levels. The fertilization rate was differently affected depending on whether sperm or eggs were pretreated; i.e., the exposure of eggs to Cd2+ promoted fertilization at relatively high Cd2+ levels. If sperm was exposed to Cd2+, a depression of fertilizing capacity was observed at high Cd2+ levels, while lower Cd2+ levels, displayed an opposite action, resulting in an increase in fertilization rate after prolonged sperm exposure.
The antifouling compound Irgarol 1051 and its degradation product M1 (also known as GS26575), along with another antifouling compound Diuron, have recently been found in Japanese coastal waters. This study was undertaken to find the origin of these chemicals and investigate their aquatic fate. Five glass plates, each coated with 1 g of antifouling paint containing Irgarol and Diuron, were submerged in 250 ml of five different test waters and the plates removed after several months. The aqueous solutions were divided into two groups: one exposed to natural sunlight, and the other kept in the dark as a control. Irgarol and Diuron were detected in all aqueous solutions, suggesting leaching from antifouling paints is the origin of these antifouling biocides found in Japanese coastal waters. Under sunlight conditions, Irgarol underwent a rapid degradation to produce M1, which remained even after Irgarol had disappeared from the system. These compounds were persistent in any aqueous solutions tested under dark conditions, indicating high stability to hydrolysis. Diuron and M1 were more persistent than Irgarol under sunlight irradiation. Since these compounds have high herbicidal activities, their ultimate impact on aquatic ecosystems is closely related to their aquatic fate.
Sperm cell and embryo toxicity tests using the Mediterranean sea urchin Paracentrotus lividus Lmk were performed to assess the toxicity of As3+, Cd2+, Cr3+, Ni2+, Pb2+, Cu2+, Zn2+, and Hg2+. The aim of this study was to improve information about the comparative sensitivity of sea urchin bioassays to the heavy metals, which are an important cause of contamination in the ecosystem of the Lagoon of Venice. Considering the data in mM/L, the order of toxicity is Hg2+ > Cu2+ > Zn2+ > As3+ > or = Cr3+ > or = Cd2+ > or = Pb2+ > or = Ni2+ for the sperm cell test and Hg2+ > or = Pb2+ > Cu2+ > Zn2+ > Cd2+ > Ni2+ > As3+ > or = Cr3+ for the embryo test. New toxicity data for metals expressed as median effective concentration (EC50) and no-observed-effect concentration (NOEC) are reported for the Mediterranean species. Accurate observations of embryotoxic effects at increasing metal concentrations were done, detecting some different behaviors in metal toxicity. Toxicity data compared with water column and pore-water concentrations recorded in the Lagoon of Venice (Italy) demonstrate the potential ability of bioassays using sea urchin to detect important contaminants in this ecosystem.
Tens of thousands of synthetic substances are in existence today and hundreds of new compounds are being introduced every year. Because of the complexity of the physico-chemical interactions between pollutants and the marine environment, the potential toxicity of contaminants can be assessed adequately only by means of bioassays with living organisms. From a practical point of view, a bioassay needs to be sensitive and scientifically valid, yield rapid results at moderate cost, and the organism in question must be readily available. Ecotoxicological bioassays with bivalve embryos and larvae fitll these criteria better than most other tests. They have increasingly come into use during the past three decades and are now commonly employed to ascertain the biological effects of pure chemicals, as well as to determine the quality of effluents, coastal waters and sediments sampled in the field. There do not appear to be very great differences bet\veen bivalve species with regard to larval sensitivity to toxicants. The principal species for bioassays are oysters (Crassostrea gigas and C. virginica), and mussels (Mytilus edulis and M. galloprovincialis. Bioassays are conducted with gametes and larvae of all ages: sperm and unfertilized eggs, embryos, young D-larvae, intermediate umboned larvae, and pediveligers towards the end of the pelagic period. Embryos are usually the most sensitive stage. Recent advances now also permit bioassays on metamorphosing pediveligers, a method particularly suited to investigate the effects of adsorbate-contaminated surfaces. There are various criteria for the assessment of toxic effects, including embryogenesis success (abnormalities), larval growth, mortality, physiology (e.g. feeding or swimming activity), and metamorphosis success. Chronic toxicity studies may be carried out over periods of several weeks, but larval rearing in the laboratory requires considerable effort (e.g. ' cultivation of algal food). The method of choice for investigations of acute toxicity and for routine monitoring studies is the embryo bioassay because it is very sensitive, relatively simple, and produces results within 24 or 48 hours. The data obtained by different investigators are often difficult to compare, however, because of differences in methodology. There is no firmly established procedure, and further simplification and standardization of techniques is required. In bioassays with a single pollutant, the effective toxic concentration may span several orders of magnitude, depending on bioassay procedures, larval stage and choice of response. Tributyl-tin (TBT) is the most toxic compound ever bioassayed with bivalve larvae, with effective concentrations (EC50) as low as a few nanograms per litre (i.e. 10~3 ppb). Heavy metals (particularly mercury, silver and copper) are next in order of toxicity, with EC50 values between a few micrograms per litre (ppb) and several hundred ppb. Chlorine and some organochlorine pesticides may also have EC50 values of less than 100 ppb, while detergents and petroleum products are generally less toxic.
The phytotoxicity of the new antifouling compound Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) and its degradation product M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) was assessed by a battery of bioassays with marine and freshwater species. Both compounds at low concentrations affected aquatic plant species such as the red macroalga Porphyra yezoensis conchospores, the brown macroalga Eisenia bicyclis gametophytes, the freshwater green microalga Closterium ehrenbergii, the floating macrophytes Lemna gibba G3 and Lemna minor 1769. The toxicity of Irgarol 1051 was higher than that of M1 for all the aquatic plant species tested, but M1 showed a higher toxicity to root elongation of a terrestrial plant. The NOEC (0.3μg/l) of Irgarol to the brown seaweed was identical to the maximum concentration (0.296μg/l) detected in Japanese coastal waters, and the maximum concentration of M1 (1.87μg/l) detected amounted to only 20% of the NOEC value. The bioassay results suggest the possibility that both Irgarol 1051 and M1 may influence the primary producer community in the aquatic environment.
Dissolved copper, cadmium and nickel concentrations were accurately measured in surface water samples from the Torres Strait and the Gulf of Papua. The data indicated that there are significant inputs of dissolved metals to the region from the river systems that drain the mineralized areas of Papua New Guinea. The Purari River was identified as a major source of cadmium and nickel whereas the Fly River, which receives inputs from a large copper mine, was a major source of dissolved copper. Offshore, the concentrations of trace metals are close to background concentrations and were consistent with recent data for Australian coastal waters and the Pacific Ocean.
This study evaluated embryotoxicity and genotoxicity of two dissolved metals copper and cadmium (Cu and Cd) and two pesticides (metolachlor and irgarol) occurring in Arcachon Bay (SW France) in Pacific oyster (Crassostrea gigas) larvae and investigated the relationship between those two endpoints. Embryotoxicity was measured by calculating the percentage of abnormal D-shaped larvae and genotoxicity was evaluated with DNA strand breaks using the comet assay. After 24h exposure, significant increases of the percentage of abnormal D-larvae and the DNA strand breaks were observed from 0.1μgL(-1) for Cu, 10μgL(-1) for Cd and 0.01μgL(-1) for both irgarol and metolachlor in comparison with the controls. A strong positive relationship between embryotoxicity and genotoxicity was recorded for Cu, Cd and metolachlor. The current study suggests that copper, irgarol and metolachlor can induce larval abnormalities and DNA damage in a population of exposed oysters at environmentally relevant concentrations.
The concentrations of booster compounds were surveyed in the port of Osaka, Japan. The concentrations of Sea-Nine 211, Diuron and Irgarol 1051 in water samples from the port of Osaka were in the ranges <0·30–0·55 ng l ⁻¹ , 13–350 ng l ⁻¹ , 1·3–77 ng l ⁻¹ , respectively. Pyrithiones were not detected in water samples. The levels of Diuron and Irgarol 1051 in the port of Osaka were high in the mooring area for small and medium-hull vessels with poor flushing.
Susceptibility of bacterial populations in estuarine water to antifouling biocides was studied. Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione dissolved in dimethyl sulfoxide (DMSO) were added to estuarine water and number of colony forming units (CFU) of bacteria in estuarine water was counted using R2A agar plate. The CFU was not decreased at the concentration less than 1·0 mg/l of Diuron, Irgarol 1051 and Copper pyrithione. However, CFU was decreased at 0·1 mg/l of Sea-Nine 211. Degradation of Sea-Nine 211, Diuron, Irgarol 1051 and Copper pyrithione by bacteria in estuarine water was studied using a die-away method. At an initial concentrations of 0·1 mg/l, observed half-lives of Sea-Nine 211 and Copper pyrithione were 10 and 20 days, respectively. In contrast, Diuron and Irgarol 1051 were degraded scarcely during 60 days of culture.
Photodegradation of these booster biocides by sunlight and UV light were studied. Under UV, all biocides were below detection limit after one day of irradiation. Under sunlight, Copper pyrithiones were also below detection limits after one day. Drastic decrease of Sea-Nine 211 concentration was observed after one day. Diuron and Irgarol 1051 scarcely decreased during 17 days of sunlight irradiation.
Racemic metolachlor is currently being replaced by S-metolachlor, the herbicide enantiomerically enriched with the biologically active 1‘S-isomers. This “chiral switch” is expected to result in lower concentrations and in a changed enantiomer/isomer composition of the residues in the environment. To verify this switch, enantioselective gas chromatography/mass spectrometry was used to determine the enantiomer/isomer composition of metolachlor residues from two lakes in Switzerland receiving inputs from agricultural activities. As a measure of this composition, we used the enantiomer excess (EE) defined as the excess of the 1‘S- over the 1‘R-isomers. Thermal epimerization of atropisomers to ratios 1:1 made these measurements possible despite incomplete enantiomer resolution. Surface water prior to 1998, and more recent waters from the deeper regions of these lakes, showed EE values of ≈0, indicating that pre-1998 inputs were from the racemic product. In contrast, more recent surface water from these lakes showed a clear excess of the 1‘S-isomers with EE values up to 0.25 in 1998 and up to 0.64 in 1999, indicating significant contributions from the nonracemic product. The enantiomer composition of metolachlor loaded to the lakes (EEinput) was determined from measured concentrations and EE values in the lake using computer models. EEinput values derived in this way were ≈0.35 in 1998 and ≈0.65 in 1999, corresponding to substitutions of ≈55 and ≈90% of racemic by S-metolachlor, respectively. The data document the application of enantioselective determinations in environmental residues to apportion the relative contributions of old and new herbicide on the basis of enantiomer/isomer composition. Furthermore, the data show a rapid environmental response to the changed composition of the herbicide.
The most important sources of pollution by triphenyltin (TPT) in marine coastal ecosystems are its employment as a fungicide in agriculture and, in association with tributyltin, as a biocide in antifouling paints. In this study, spermiotoxicity and embryotoxicity (from post-fertilization to pluteus stage) experiments were carried out to clarify better the ecotoxicological effects of TPT during the development of the sea urchin Paracentrotus lividus. Sperm exposed to triphenyltin acetate (TPTA) for 60 min showed a significantly reduced capability to fertilize eggs even at the lowest TPTA concentration of 0.1 µg l−1. In proportion to increasing TPTA concentrations, the percentage of fertilized eggs decreased, falling to 45% at 10 µg l−1, the maximum TPTA concentration tested. In embryotoxicity experiments at 48 h post-fertilization, the length of the pluteus somatic rods was significantly reduced (P < 0.001) at 1.5 µg l−1 and above. Progressive increases in skeletal anomalies were also detected, which were highly significant (P < 0.001) at 2 µg l−1. Embryonic development was greatly slowed at the highest TPT concentrations: embryos never reached the pluteus stage at 5 µg l−1, and development was blocked at the gastrula stage at 10 µg l−1. As observed in previous experiments using butyltin compounds, embryotoxic effects on both skeletal deposition and blocked development are presumed to be due to interference of TPT with intracellular calcium homeostasis. Sea urchin gametes are more sensitive to TPT than embryos, this condition emphasising the environmental risk due to TPT contamination. Copyright © 2002 John Wiley & Sons, Ltd.
Spermio- and embryotoxicities of Cu, Ag, Cd, and Hg were investigated in Paracentrotus lividus, the dominant echinoid species of the Mediterranean. Spermiotoxicity was studied by assessing the effects of sperm exposure on fertilization rate (FR) as well as on the induction of transmissible damages to the offspring. Embryotoxicity was studied by assessing developmental defects in larvae exposed to the tested metals throughout their development. Sperm exposures resulted in significant decreases of FR, depending on both metal concentration and duration of the exposure. Lowest spermiotoxic concentrations recorded when sperm were exposed for 75 min to the metals were 10−7 M Hg(II), 10−6 M Ag(I), 10−5 M Cu(II), and 10−5 M Cd(II). Tested metals did not exert any transmissible damage to spermatozoa that could result in larval malformations in the offspring, even for concentrations that dramatically reduced FR. Single-element exposures of embryos for 72 h resulted in developmental defects whose occurrence and severity showed a steep dose dependence, indicating that once a threshold is reached, any further increase in toxicant concentration rapidly enhances the impairment of target function(s). Those observations suggest the involvement of a saturable protective mechanism. Lowest observed embryotoxic concentrations of the metals were 10−7 M Hg(II), 2.5 × 10−7 M Ag(I), 5 × 10−7 M Cu(II), and 10−5 M Cd(II) and are in the range of concentrations reported in heavily polluted marine environments. Thus, the possibility of impairment of echinoid development actually exists in metal-contaminated marine environments, possibly threatening echinoid populations in those environments.
A simple sperm/fertilization bioassay, primarily using sea urchin (and sand dollar) gametes, was improved to yield a quick, sensitive, and cost-effective procedure for measuring toxicity in marine waters. Standard sperm bioassays are conducted by exposing sperm cells to test solutions for 60 min prior to addition of eggs to the test solution for fertilization. Reduced fertilization success (as indicated by the presence or absence of the obvious fertilization membrane) is used as an indicator of toxic effects on sperm viability and/or the fertilization response. This study, in conjunction with earlier work, has shown that the results of sperm bioassays can be affected by a number of factors including temperature, pH, salinity, sperm:egg ratios, sperm exposure times, test materials, and echinoid species. Each of these factors have been considered in designing the standard conditions for the improved test. Examples of the effect of these factors on the test results are illustrated, using silver as a reference toxicant.
Six developmental stages of the bay mussel Mutilus edulis, from fertilization to 32 h after fertilization, and also unfertilized eggs, were exposed for 1 h to different concentrations of the insecticide Sevin and its first hydrolytic product, 1-naphthol. After exposure, the larvae or eggs were separated from the pesticide solution and returned to clean water. At 48 h after fertilization, the numbers of normal and abnormal larvae were determined and 1-h EC50 values (the effective concentrations that caused anomalous development of 50% of the test animals) were calculated. The most sensitive developmental stage was the one that occurred shortly after fertilization at the time of appearance of the first polar body. Thereafter, sensitivity decreased as age increased. The EC50 of Sevin for the first polar body stage and 32-h stage were 5.3 and 24.0 mg/l of Sevin, respectively. The EC50 of l-naphthol for the first polar body stage was 5.2 mg/l. Effects of the toxicants on development were characterized by disjunction of blastomeres, a reduction in the rate of development, and asynchronous and unaligned cleavages.
A simple sperm/fertilization bioassay, primarily using sea urchin gametes, has been developed and used by a variety of laboratories. This assay was recently refined into a standard test and is now being used by the U.S. Environmental Protection Agency and others for toxicity testing in marine waters. One factor that has lagged behind the development of this assay is the comparison of its sensitivity to various common toxicants as compared to other bioassay systems and life stages of other marine organisms. The objective of this study was to compare the sensitivity of a standardized sea urchin sperm/fertilization assay to the responses of embryo, larval, and adult marine organisms to metals (Ag, Cd, Cu, Pb, Zn) and pesticides (DDT, Dieldrin, Endrin, Endosulfan) added to natural seawater. The results, although highly variable, generally showed that sperm/fertilization and embryo assays were quite sensitive to the metals tested, but that the larval and adult assays were more sensitive to the pesticides. These comparative data, together with other studies of complex effluents, show that the standardized sperm/ fertilization bioassay is an especially quick and useful tool for biomonitoring of marine waters.
The gametes, embryos, and early larvae of the surf clamSpisula solidissima were exposed to silver at concentrations up to 65 g/L. All experiments were conducted at 20C and 30 S, and lasted up to 48 hr after fertilization. Forty-five minute exposures of eggs to 16 g/L or more silver just prior to fertilization in non-silver seawater lead to production of abnormal larvae. Simultaneous exposures of eggs and sperm to silver concentrations up to 21 g/L for 45 min did not prevent fertilization but did produce abnormal larvae at silver concentrations greater than 6 g/L. Postfertilization treatments of zygotes, embryos, and larvae lead to fewer abnormalities than prefertilization or fertilization treatments of comparable exposure length and concentration. The greatest numbers of abnormalities and mortalities were observed in continuous exposures, from gametes through fertilization to 48 hr postfertilization. Variability in % normal development was greater in high than in low silver concentrations.
Residue analyses and ecotoxicity assessment were conducted on the new antifouling compound Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) and its degradation product M1 (2-methylthio-4-tert-butylamino-6-amino-s-triazine) in order to delineate the environmental fate and impact of Irgarol 1051 on the aquatic ecosystem. For the first time, the Irgarol degradation product (M1) was positively identified in environmental samples. During the 1998 Irgarol survey, concentrations of M1 (up to 1870 ng/l) were generally higher than those of Irgarol in the coastal waters of the Seto Inland Sea in Japan, suggesting a greater environmental persistence for M1 than for the parent compound Irgarol 1051 in the aquatic ecosystem. Ecotoxicity testing revealed that Irgarol 1051 and M1 were moderately toxic to a marine bacterium and the four crustaceans tested, but were highly toxic to some algae and higher plants. In the root elongation inhibition bioassay, M1 showed a phytotoxicity at least 10 times greater than that of Irgarol and six other triazine herbicides (terbutryn, terbutylazine, terbumeton, simetryn, atrazine and simazine). These results strongly suggest that both Irgarol 1051 and its persistent degradation product M1 may potentially affect and/or damage the primary producer community in aquatic ecosystems. To safeguard the aquatic ecosystem from the damaging impact of micro contaminants, it is recommended that, besides monitoring for the target parent compound, major degradation products should also be included in environmental surveys. Otherwise, there is a risk of underestimating the ultimate impact of a particular toxicant on the environment.
The proposed International Maritime Organization (IMO) ban on tributyltin (TBT) as an antifouling paint biocide, will raise the inevitability of the increased use of alternative paints containing copper and organic booster biocides. Although the fate of TBT in marine sediments has been extensively studied, very little work has been performed to assess the accumulation of organic booster biocides in sediments. A survey was conducted to determine concentrations of TBT, Irgarol 1051, the Irgarol 1051 metabolite GS26575 (2-(tert-butylamino)-4-amino-6-(methylthio)-1,3,5-triazine; also referred to as M1) and diuron in coastal and off-shore sediments. TBT was consistently determined at the highest concentrations and was detected in all sediments collected from Southampton Water, UK, along with the TBT degradation product dibutyltin (DBT). Irgarol 1051 was detected (0.01–0.11 μg/g) in some sediments collected from marinas, where high concentrations of these compounds have been measured in surface waters. The Irgarol 1051 metabolite 2-methylthio-4-tert-butylamino-6-amino-s-triazine (M1/GS26575) was only detected at a few locations at concentrations <0.001 μg/g, although higher concentrations were determined in surface waters (13–99 ng l−1). Diuron, thought to be present in the form of antifouling paint particles, was determined at a concentration of 1.4 μg/g in an enclosed marina. All analytes were found to be below the limit of detection in the sediments collected off-shore. The potential accumulation in sediments of the other two booster biocides currently used in the UK, zinc pyrithione and dichlofluanid, are also discussed.
The biochemical composition of eggs spawned from mussels Mytilus galloprovincialis (Lamarck) collected from Galician Rias (Spain) is, in general, similar to that indicated for other marine molluscs. Proteins (45% of total dry weight) and lipids (22%) are the main reserves of the egg while carbohydrates (3%) are the lowest constituent. Egg diameter showed a mean value of 61 μm and egg density followed an unimodal distribution of frequencies with a mean value of 1.057 g · cm−3. Fertilization of the eggs of M. galloprovincialis can be delayed for about 4 to 8 h after spawning over the temperature range of 10 ° to 18 °C. After these times, percentage of fertilized eggs decreased to less than 30%. At 18 °C the low values in successful fertilization may be due to the degradation of the eggs. A delay in addition of sperm after release of the eggs increases the time in which first cell cleavage appears from the moment of insemination. Variation of the biochemical composition of unfertilized eggs over time was also studied. At 18 °C proteins, lipids and carbohydrates decreased by about 45, 46 and 48%, respectively, after 5 h (only 4% of total eggs were fertilized) from spawning. At 10 ° and 14 °C the decreases after 11 and 8 h from spawning, respectively, were lower. Before these times, the decrease of biochemical constituents was not so great and fertilization rates were still high.
The use of antifouling paints containing tributyltin as a biocide is now limited to vessels greater than 25 m in length. Consequently, manufacturers have introduced additional biocides which are generally used in combination with copper. These biocides are termed booster biocides, and currently there are nine approved for use on leisure craft. The environmental impact of tribuyltin and copper on the environment is well documented. However the potential for the other biocides to cause pollution has not been quantified. A survey was therefore performed to determine the quantity of each of the biocides released to coastal waters. Copper(I) oxide was used in highest quantities followed by diuron, copper thiocyanate, Irgarol 1051, zinc pyrithione and dichlofluanid. Monitoring studies agreed with the survey, concentrations of copper being highest followed by diuron and irgarol. High concentrations of zinc were also observed, probably arising from sacrificial anodes. Generally, predictions of biocide concentrations, obtained using an existing exposure model, were similar to measured concentrations, indicating that this model is a useful screening tool for risk assessment purposes.
The impact of tributyltin (TBT), was investigated on the occurrence of early gamete contacts and the functioning of the ionic channels of unfertilized or fertilized egg of Phallusia mammillata. TBT significantly inhibited the Na+ current of unfertilized oocytes up to 60%, in both a dose (1–10 μM) and time (30 min to 8 h) dependent manner, while it moderately affected the Ca2+ and K+ currents. Also TBT induced a statistically significant dose-dependent decrease in the percentage of eggs that responded electrically to fertilization (from 100 to 33%, respectively, for 0.1–3 μM TBT). As the sperm concentration increased, the dose-response curve of the percentage of eggs that responded electrically to fertilization shifted towards higher TBT concentrations which did not affect the capability for sperm to fertilize eggs. The effects of TBT were weakly reversible, depending on both TBT concentrations and the duration of incubation in TBT solutions. TBT (5 μM) prevented early sperm egg contacts (5×107 sp ml−1) at the vestment level of intact eggs, but did not lower the percentage of electrical responses in naked eggs. Nevertheless, it had a deleterious effect on the transduction mechanism of the sperm signal into the egg or, more directly, on the sperm-activated channels of the egg membrane. This was evidenced by naked eggs displaying strongly truncated electrical responses, although they were penetrated by sperm-nuclei. Finally, N-acetylglucosamine, an intrinsic vitelline coat (VC) monosaccharide involved in the sperm binding to VC, added (100 mM) to 5 μM TBT in natural seawater, in order to compete with the pollutant, did not reduce the deleterious effect of TBT on the early gamete contacts at VC level.
Effects of cadmium on the fertilizing capability of spermatozoa, dynamics of the first cleavage and pluteus formation in the sea urchin, Anthocidaris crassispina, were investigated. Exposure to cadmium concentrations of 0.32, 0.56, 1.0, 1.8, 3.2, 5.6 and 10.0 mg l−1 for 30 min caused a significant adverse effect on the fertilizing capability of spermatozoa (EC50=1.7 mg l−1). For the first cleavage kinetics assay, eggs were pre-exposed to 0, 0.18, 0.32, 0.56, 1.0, 1.8, 3.2 and 5.6 mg l−1 of cadmium for 30 min. Fresh sperms of fixed concentrations were then added to the eggs and the percentage of divided zygotes estimated. Concentration-dependent toxic effects on the dynamics of the first cleavage in A. crassispina were observed between 0.18 and 5.6 mg l−1 cadmium. Calculation of EC50 values by probit analysis at different stages of the first cleavage revealed that EC50 values increased gradually from 0.37 mg l−1 at the beginning to 2.24 mg l−1 at the end of the cleavage process. Different larval classes (normal, abnormal and retarded plutei, preplutei, dead embryos/larvae) of A. crassispina obtained from eggs pre-treated with cadmium for 30 min and then exposed to cadmium throughout embryogenesis were also examined. The percentage of abnormal plutei was significantly higher than that of the control at 0.56 mg l−1 cadmium and higher. The 48 h EC50 calculated for the number of normal plutei was 1.5 mg l−1. A χ2-test revealed significant changes in the distribution of proportions of different larval classes only at cadmium concentrations ⩾1.8 mg l−1. At 5.6 mg l−1 of cadmium, small malformed plutei, and oval embryos with rudimentary skeleton, poorly differentiated intestines and no mouth (pre-pluteus stage) were observed. The relative sensitivity of various end points to cadmium is also compared and discussed.
In the late 1980s, a number of countries restricted the use of tri-n-butyltin (TBT) as an active ingredient in antifouling paint for small boats, including pleasure craft. Irgarol 1051—2-(tert-butylamino)-4-(cyclopropylamino)-6-(methylthio)-1,3,5-triazine, belonging to the s-triazine group of herbicides—is now used in combination with copper in several antifouling products. Irgarol 1051 contamination of the marine environment was studied close to a marina on the west coast of Sweden. Highest concentrations (1.6 nm, 0.4 μg l−1) were observed during the peak of the boating season. To investigate the potential for toxic effects, marine periphyton communities were established on artificial substrata in 22-litre flowthrough aquaria and exposed to Irgarol 1051 during a 3-week period in April 1994. The algicide was continuously added at concentrations ranging from 0.06 to 260 nm. Irgarol 1051 was found to significantly (p < 0.05) inhibit periphyton photosynthetic activity at 3.2 nm in short-term (hour) tests. Long-term (weeks) exposure produced effects at even lower concentrations. A significant change in community structure was found at 1 nm, which produced a shift towards tolerant species. Photosynthetic activity and algal biomass (chlorophyll a content) was significantly lowered at concentrations of 1 and 4 nm, respectively, indicating only minor functional redundancy in the communities. The most sensitive long-term effects were detected at 0.25-1 nm (0.063–0.25 μg l−1) of Irgarol 1051, which is within the concentration range detected in the contaminated areas around the marina. It can be concluded that the present use of Irgarol 1051 is likely to damage microalgal communities in contaminated coastal waters.
Acute toxicity of pesticides in water was assessed singly and in mixtures using various responses of the luminescent bacterium Vibrio fischeri, the aquatic invertebrate Daphnia magna, and the MitoScan™ assay. The latter utilized fragmented mitochondria to enzymatically convert oxidized β-nicotinamide adenine dinucleotide (NAD+) to its reduced form, NADH. The rate of the conversion being sensitive to the type and concentration of toxicants. The pesticides tested were carbofuran, cyromazine, fenamiphos, formetanate, and propamocarb. The aqueous solubility of all compounds exceeded 320 mg l−1. All the toxicity bioassays were characterized in terms of relative sensitivity and complementarity. Synergistic and antagonistic toxicity effects were observed with pesticide cocktails relative to pure compound toxicities. The D. magna assay was the most sensitive and best able to detect toxic interactions of mixtures. Cyromazine was the least toxic of the pesticides tested.
We used photosynthetic activity (measured as chlorophyll a fluorescence) and photosynthetic pigment concentrations to assess the effect of pulsed exposure to catastrophic levels of the herbicides Atrazine, Diuron and Irgarol 1051 on the seagrass Zostera capricorni Aschers. in laboratory and field experiments. Custom-made in situ chambers were developed so seagrasses could be dosed within the meadow. Zostera capricorni was exposed to 10 and 100 μg l−1 herbicide solutions for 10 h. During this time and for the subsequent 4-day recovery period, chlorophyll a fluorescence parameters (maximum quantum yield: Fv/Fm and effective quantum yield: ΔF/Fm′) were measured. Laboratory samples exposed to these herbicides were severely impacted during the exposure period and most treatments did not recover fully. ΔF/Fm′ was a more sensitive indicator of herbicide impact than Fv/Fm. In situ samples were also severely impacted by Irgarol and Diuron exposure whereas samples recovered completely after exposure to Atrazine at the same concentrations as the laboratory experiments. Total chlorophyll concentrations showed only limited impact in both laboratory and field situations. This study suggests that laboratory experiments may overestimate the on-going impact of herbicides on seagrass.
Antifouling biocides used in boat paints were analyzed with a battery of toxicity bioassays to evaluate the toxic effects of these compounds on Vibrio fischeri, Daphnia magna and Selenastrum capricornotum. The antifoulants tested were Irgarol 1051, Kathon 5287, chlorothalonil, diuron, dichlofluanid, 2-thiocyanomethylthiobenzothiazole (TCMTB) and tributyltin (TBT). In most cases, the sensitivity of the organisms towards the toxicants followed the order: S. capricornotum > D. magna > V. fischeri. Toxicity by concentration level had the following order: TBT=Kathon 5287>chlorothalonil>Irgarol 1051>diuron>dichlofluanid>TCMTB for S. capricornotum. For D. magna (48 h test), the toxicity order of compounds was TBT>Kathon 5287>chlorothalonil>TCMTB>dichlofluanid>Irgarol 1051>diuron. For V. fischeri (30 min test), the compound toxicity had the following order: Kathon 5287>TBT>TCMTB>dichlofluanid>Irgarol 1051>chlorothalonil.Degradation products of Irgarol 1051 and diuron were also tested. Degradation product of Irgarol 1051 was found to be less toxic to the crustacean and the microalga but more toxic to the bacterium. Degradation products of diuron were less toxic to the microalga in comparison with the bacterium. For mixtures of compound, toxicities were additive in only 33% of the cases and 21% of mixtures were less toxic than expected based on the sum of concentrations of toxicants (antagonistic effect). Synergistic enhancements of toxicity were observed for a majority (46%) of the mixtures.The average reproducibility of the EC50 and LOEC measurements was 27, 24 and 28%, respectively, in the V. fischeri, S. capricornotum and D. magna bioassays. For single compound, the reproducibility of EC50 was better than ±20% for a vast majority of the measurements with the V. fischeri system, thus agreeing closely with the reported reproducibility values for this relatively well-known assay.
We investigated the effects of genotoxicant exposure in gametes and embryos to find a possible link between genotoxicity and reproduction/developmental impairment, and explore the impact of chemical genotoxicity on population dynamics. Our study focused on the genotoxic effects of two herbicides on oyster gametes and embryos: glyphosate (both as an active substance and in the Roundup formulation) and diuron. France is Europe's leading consumer of agrochemical substances and as such, contamination of France's coastal waters by pesticides is a major concern. Glyphosate and diuron are among the most frequently detected herbicides in oyster production areas; as oyster is a specie with external reproduction, its gametes and embryos are in direct contact with the surrounding waters and are hence particularly exposed to these potentially dangerous substances.
Toxicity studies on sperm often use fertilization success as the end point. This type of assay can be affected by sperm density, egg quality, and sperm-egg compatibility. Testing sperm viability biomarkers with flow cytometry is a fast, high-throughput technique for seminal analysis. In this study, we detected sperm viability biomarkers with several fluorescent reporter dyes using flow cytometry in three aquatic invertebrates (Crassostrea virginica, Dreissena polymorpha, and Lytechinus variegatus) after exposure to a pesticide and herbicide. The pesticide, Bayluscide, appeared to affect mitochondrial membrane potential in the sperm of all three species, as measured with MitoTracker Red CMXRos. A decrease in the percentage of sperm stained with SYBR-14 (indicating uncompromised plasma membrane) was observed in C. virginica and D. polymorpha sperm exposed to Bayluscide, but propidium iodide staining (indicating compromised plasma membranes) appeared to be inhibited by Bayluscide. Acrosome-reacted sperm, as measured by FITC-PNA, decreased after Bayluscide exposure in C. virginica and D. polymorpha sperm. The herbicide, Roundup Ready To-Use-Plus, did not affect the overall percentages of sperm stained with MitoTracker but did cause an increase in MitoTracker fluorescence intensity at 16 mg/L in D. polymorpha. Roundup also caused significant decreases in SYBR-14 staining, significant increases in propidium iodide staining, and significant increases in FITC-PNA staining in D. polymorpha sperm. By not having to rely on egg availability and optimal sperm density, sperm toxicity can be more accurately assessed with flow cytometry as being directly correlated to sperm viability rather than the possibility of altered toxicity results due to sperm-to-egg compatibility.
We examined the toxicity mitigation efficiency of a hydrologically modified backwater wetland amended with a pesticide mixture of atrazine, metolachlor, and fipronil, using 96 h survival bioassays with Hyalella azteca. Significant H. azteca 96 h mortality occurred within the first 2 h of amendment at the upstream amendment site but not at any time at the downstream site. H. azteca survival varied spatially and temporally in conjunction with measured pesticide mixture concentrations. Hyalella azteca 96 h survival pesticide mixture effects concentrations ranges were 10.214–11.997, 5.822–6.658, 0.650–0.817, and 0.030–0.048 μg L−1 for atrazine, metolachlor, fipronil, and fipronil-sulfone, respectively.
Tests with naturally-occurring sediments are rare and sediment testing methodology is not standardized. The authors present a simple methodology for undertaking sediment bioassays with oyster larvae, and present data from a recent study to prove the utility of this method.
Irgarol 1051 (2-methylthio-4-tert-butylamino-6-cyclopropylamino-s-triazine) is an antifouling agent used in paint formulations that are applied to the hulls of ships. A survey was carried out at Conwy Marina in North Wales to determine the levels of the herbicide over a period of three months. Liquid/liquid extraction was used to concentrate the analyte for quantitative analysis using gas chromatography/mass spectrometry (GC/MS) in the selected ion monitoring (SIM) mode. The concentrations of Irgarol 1051 in Conwy marina ranged from 7 to 543 ng/l, similar to the levels found in many other marinas, estuaries and ports in England, although much lower than those in Côte d'Azur, France. The concentrations of Irgarol 1051 were not found to be influenced by salinity, pH or temperature, although there is a strong correlation between the average concentrations of Irgarol 1051 and the density of boating activity. At the levels found in the marina, it is possible that non-target photosynthetic inhibition could occur.
Successful reproduction is a determining factor for species survival. Pollution may impair reproductive success of adults through effects on gamete quality. Reproductive impairment of the sea urchin Anthocidaris crassispina upon chronic (4 weeks) exposure to 0.01 and 0.1 mg l-1 Cd2+ was investigated. Criteria used for assessing gamete quality included sperm motility, egg morphology, fertilization rate and dynamics of first cleavage. A dose-response relationship was found between Cd2+ levels and changes in sperm motility, and percentage fertilization. Sperm motility, measured by computer-assisted sperm analysis, indicated that percent motile sperm, velocities, and percent sperm with normal trajectory were significantly affected by chronic exposure to > or = 0.1 mg l-1 Cd2+. A decline in sperm motility was also accompanied by a decrease in fertilization success of sea urchin sperm. Width/height ratio of sea urchin eggs was not affected by cadmium, but larger egg sizes were found when sea urchins were exposed to 0.1 mg l-1 Cd2+. Male sea urchins exposed to Cd2+ produced poorer quality sperm, as indicated by a lower percent fertilization and lower cleavage rate, implying that male sea urchins were more sensitive than females to chronic Cd2+ exposure. Results of the present study provide an explanation of reproductive impairment in marine invertebrates upon chronic exposure to Cd2+.
A compilation of the results of a monitoring program of the recently used antifouling pesticides diuron (3-(3,4-dichlorophenyl)-1,1-dimethylurea), Irgarol 1051 (2-methylthio-4-tertiary-butylamino-6-cyclopropylamino-s-teiazine), seanine 211 (4,5-dichloro-2-n-octyl-4-isothazolin-3-one), chlorothalonil (2,4,5,6-tetrachloro-isophthalonitrile), dichlofluanid (N'-dimethyl-N-phenylsulphanamide), TCMTB ((2-thiocyanomethylthio) benzothiazole), and three degradation products demethyldiuron (3-(3,4-dichlorophenyl)-1-methylurea),3,4-dichlorophenylurea and 2-methylthio-4-tert-butylamino-s-triazine (Irgarol degradation product) that was carried out between April 1996 and February 2000 in enclosed seawaters from Catalonia and Almería (Spanish Mediterranean coast) is reported. Nine points were sampled along the Catalan coast: Barcelona Olympic port, Masnou, Blanes, Sant Carles de la Ràpita, Tarragona, Cambrils and Salou marinas as well as the Cambrils and Tarragona fishing harbors and in marinas and ports from Almeria: Aguadulce port, Almería port, Almerimar fishing harbour and Almerimar marina. The analytical methodologies were based on Solid Phase Extraction followed by liquid chromatography (LC) or gas chromatography (GC) coupled to a mass spectrometry (MS) or -Diode Array Detector. The main pollutants found in the sampled points were diuron and Irgarol 1051 that were detected at concentrations up to 2.19 micrograms l-1 and 0.33 microgram l-1, respectively. On the other hand, seanine 211 was found at the highest concentration (up to 3.7 micrograms l-1) during the summer of 1999. Low concentrations of dichlofluanid and the above mentioned degradation products were detected for the first time in the Spanish coasts. Chlorothalonil, TCMTB were not found at concentrations higher than 1 and 20 ng l-1 respectively which were the limit of determination (LOD) of the method for these compounds. In general the contamination at the different marinas is higher at the end of spring and in summer where the boating activity is also higher. This paper shows for the first time that the contamination by the new antifouling pesticides in Spanish coastline, basically marinas and fishing harbours, is permanent along the whole calendar year. So, preventive actions by the harbour authorities will be needed in the near future in order to monitor and control the levels and effects of the new antifouling biocides in the marine environment.
Gametes (sperm) and fertilized eggs (embryos) of the Mediterranean sea urchin, Paracentrotus lividus, and the Japanese oyster, Crassostrea gigas, were used to investigate the toxicity of two marine sediments, one polluted by polycyclic aromatic hydrocarbons (PAH) and the other by heavy metals. The sediment samples were freeze-dried for storage, and three different treatments were used for analysis: whole sediment, unfiltered elutriate, and filtered elutriate. The two sediments were toxic to sea urchin spermatozoa but not to oyster spermatozoa, and embryotoxicity was almost always the more sensitive endpoint for toxicity assessment. As a rule, whole sediment was more toxic than the elutriates by nearly two orders of magnitude. With respect to embryotoxicity, the whole sediments and the elutriates of the PAH-contaminated sediment were more toxic to oyster embryos, whereas the elutriates of the sediment polluted by heavy metals had stronger effects on sea urchin embryos. The results confirm that bioassays with Japanese oyster embryos provide a more sensitive appraisal of toxicity in the marine environment than bioassays with other developmental stages. As a whole, Mediterranean sea urchins and Japanese oysters were similar in overall sensitivity and are therefore both equally suited as bioassay organisms, but tests with oysters are more reproducible because of the better performance of the controls.
The effects of tributyltin (TBT) on the energy metabolism and motility of fish spermatozoa were investigated in vitro in African catfish and common carp. A significant (P<0.05) decrease of the duration and the intensity of motility was observed in catfish spermatozoa exposed to 0.27 microg/l TBT for 24 h. Exposure of catfish spermatozoa to 2.7-27 microg/l TBT caused an instant decrease in ATP content. In the presence of 27 microg/l TBT approximately 55% of the initial ATP concentration in catfish semen was lost after 60 min incubation while AMP concentrations increased and the total adenine nucleotide (TAN) pool remained unchanged. The reduction in sperm ATP levels could not be attributed to cell death since viability decreased only slightly over the period of exposure. In carp by contrast, none of the adenylates concentrations studied (ATP, ADP and AMP) were affected by TBT exposure at any experimental condition. However, carp sperm motility was significantly reduced by exposure to 2.7 microg/l TBT. Among the enzymes investigated only lactate dehydrogenase (LDH) in catfish sperm was significantly (P<0.01) affected by 27 microg/l TBT treatment with a reduction in activity of approximately 75%. Compared with carp sperm before TBT exposure, that of catfish had lower adenylate contents and overall lower enzymatic activities; this explains its slower sperm velocity and shorter duration of movement as measured by computer assisted sperm analysis (CASA). The present in vitro study shows that catfish spermatozoa are more sensitive to TBT exposure (and probably to other toxicants) than those of carp.
Risk indicators provide an interesting way to compare chemical substances with respect to the risks of their large-scaled release. The present study implies that, for antifouling agents used in commercial shipping, residence times in the marine biosphere are especially suitable to represent their inherent potential to cause exposure of organisms. A simple box model is described providing the possibility to estimate residence times in the marine biosphere from water-particle equilibrium partitioning constants and half-lives in water and sediment. Resulting residence times in the marine biosphere range from about 5 d (4,5-dichloro-2-n-octyl-4-isothiazolin-3-one) up to about 40,000 yr (copper). For an evaluation of the validity of the model, calculated values are compared with measured environmental concentrations. Remaining uncertainties are also discussed. The main purpose of the presented residence times is to serve as a basis for decisions in antifouling paint development or environmentally conscious purchasing of antifouling paints.
A simple, rapid toxicity test was developed using the suspension-cultured fish cell line CHSE-sp derived from chinook salmon Oncorhynchus tshawytscha embryos in order to assess the toxicity of new marine antifouling compounds. The compounds tested were copper pyrithione, Diuron, Irgarol 1051, KH101, Sea-Nine 211, and zinc pyrithione, all of which have been nominated in Japan as possible replacements for organotin compounds. The in vitro acute toxicity (24-h EC50) of the six compounds to these fish cells was evaluated using the dye Alamar Blue to determine cell viability, and then correlated with the results of in vivo chronic toxicities (28-day LC50) to juvenile rainbow trout Oncorhynchus mykiss. The suspension-cultured fish cells were found to be suitable for the screening of such chemicals before performing an in vivo test. The toxicities of the test compounds obtained from both tests, shown in decreasing order, were as follows: copper pyrithione > zinc pyrithione > KH101 > or = Sea-Nine 211 > Diuron > Irgarol 1051. The herbicides Diuron and Irgarol 1051 showed the least toxicity, while the pyrithiones had the greatest toxicity.
Irgarol 1051 is a recent herbicidal compound, inhibitor of photosynthesis, used in antifouling paints. This toxic is persistent in aquatic environments, with low abiotic and biotic degradation, highly phytotoxic, and has already been detected in estuaries and coastal areas, with suspected negative impacts on non-target organisms (aquatic plants and algae). We measured the toxicity of Irgarol 1051 to macrophytes and phytoplankton from Lake Geneva (between Switzerland and France) by determining chlorophyll fluorescence yield, and phytoplankton primary production. Long-term toxicity for phytoplankton was estimated in a microcosm study, and growth inhibition tests were performed with isolated algal strains. The concentration of Irgarol 1051 was analysed in the water, and the most polluted site showed a higher level (up to 135 ng/L) than the lowest observed effect concentration for phytoplankton (8-80 ng/L), while the macrophytes appeared to be more tolerant to Irgarol 1051 in short-term tests. The microcosm study showed that phytoplankton structure might be even more sensitive to Irgarol 1051.
This study considered the inputs of antifouling paint booster biocides into the aquatic environment directly from painted hulls and high pressure hosing operations, the occurrence of booster biocides in marinas, harbours and docks, and the influence of degradation and water-sediment partition on their environmental fate. Irgarol 1051, the Irgarol 1051 degradation product GS26575, diuron, and the diuron degradation products 1-(3-chlorophenyl)-3,1-dimethylurea (CPDU), 1-(3,4-dichlorophenyl)-3-methylurea (DCPMU) and 1-(3,4-dichlorophenyl)urea (DCPU) were all detected at measurable concentrations in surface waters. Irgarol 1051, GS26575 and diuron were also detected in bottom sediments. A preliminary study of biocide input during both normal use and foreshore hull hosing showed that hosing may be a significant point source input and also be a cause for future concern since much of this input is in the form of paint particles. Field based measurements and laboratory experiments showed that Irgarol 1051 and diuron persist in the water column, due to a low affinity to partition onto sedimentary material and high resistance to degradation. Other biocides such as chlorothalonil, dichlofluanid, and Sea-Nine 211 were all found to be rapidly removed from the water column and be less persistent.
International regulation of organotin compounds for use in antifouling paints has led to the development and increased use of replacement compounds, notably the s-triazine herbicide Irgarol 1051. Little is known about the distribution of Irgarol 1051 in tropical waters. Nor has the potential impact of this triazine upon photosynthesis of endosymbiotic microalgae (zooxanthellae) in corals been assessed. In this study Irgarol 1051 was detected in marinas, harbours and coastal waters of the Florida Keys, Bermuda and St. Croix, with concentrations ranging between 3 and 294 ng 1(-1). 14C incubation experiments with isolated zooxanthellae from the common inshore coral Madracis mirabilis showed no incorporation of H14CO3- from the sea water medium after 4-8 h exposure to Irgarol 1051 concentrations as low as 63 ng 1(-1). Reduction in net photosynthesis of intact corals was found at concentrations of l00 ng 1(-1) with little or no photosynthesis at concentrations exceeding 1000 ng 1(-1) after 2-8 h exposure at all irradiances. The data suggest Irgarol 1051 to be both prevalent in tropical marine ecosystems and a potent inhibitor of coral photosynthesis at environmentally relevant concentrations.
Tributyltin oxide (TBTO) has been used worldwide in marine antifouling paints as a biocide for some time. However, it produced toxic effects, especially in marine water/sediment ecosystems. Consequently, its use in antifouling paints has been prohibited in many countries. In this study, the toxicity of alternative and/or new antifouling biocides compared with TBTO is assessed by a biological method. The effects of these chemicals on marine species have not been well studied. This paper assesses, comparatively, the effects of eight biocides on sea urchin eggs and embryos. The chemicals assessed were TBTO, Irgarol 1051, M1 (the persistent degradation product of Irgarol), Diuron, zinc pyrithione, 'KH101', 'Sea-Nine 211', and copper pyrithione. For these chemicals, toxicity appears to be in the order zinc pyrithione > Sea-Nine 211 > KH101 > copper pyrithione > TBTO > Diuron approximately = Irgarol 1051 > M1. Here, we show that zinc pyrithione, Sea-Nine 211, KH101, and copper pyrithione are much more toxic to sea urchins than TBTO or the other chemicals.
A sensitive LC-electrospray MS-MS method using off-line solid-phase extraction for the determination of diuron and Irgarol 1051 has been developed, enabling determination of both compounds at sub-ppt levels. Diuron and Irgarol 1051 are used as alternatives for tributyltin in antifouling paints that prevent growth on boats, and an increase in their application is anticipated because of the upcoming ban on tributyltin in 2003. In 2000, a survey was carried out to assess contamination with diuron and Irgarol 1051 of a number of Dutch marinas and coastal waters. Depending on the time of year, both compounds were encountered at levels higher than the maximum permissible concentrations of 430 and 24 ng/l for diuron and Irgarol 1051, respectively. Outside marinas at reference locations, concentrations were much lower, depending on the geographical situation and the nature of the water exchange with the environment related to tidal cycles. A seasonal influence was observed with highest levels in summer, corresponding to the yachting season for both compounds. For diuron, use in agriculture could have contributed to the high concentration encountered in surface waters.
Organic booster biocides were recently introduced as alternatives to organotin compounds in antifouling products, after restrictions imposed on the use of tributyltin (TBT) in 1987. Replacement products are generally based on copper metal oxides and organic biocides. This ban has led to an increase in alternative coating products containing the above biocides. The most commonly used biocides in antifouling paints are: Irgarol 1051, diuron, Sea-nine 211, dichlofluanid, chlorothalonil, zinc pyrithione, TCMS (2,3,3,6-tetrachloro-4-methylsulfonyl) pyridine, TCMTB [2-(thiocyanomethylthio) benzothiazole], and zineb. Since 1993, several studies have demonstrated the presence of these biocides in European coastal environment as a result of their increased use. More recently, the presence of these biocides was also revealed in waters from Japan, United States, Singapore, Australia and Bermuda. This paper reviews the currently available data on the occurrence of these biocides in the aquatic environment. Some data dealing with the environmental fate, partitioning, behaviour and risk assessment of antifouling paint booster biocides are also reported in order to discuss the detected levels of contamination.
The acute toxicity of diazinon in combination with atrazine concentrations of 5, 10, 20, and 40 microg/L was evaluated using Ceriodaphnia dubia. Atrazine concentrations as low as 5 microg/L in combination with diazinon significantly increased toxicity to C. dubia compared to diazinon alone. Atrazine and diazinon residues within water samples collected from 65 subbasins throughout Denton, Texas, USA were used to assess the environmental relevance of pesticide concentrations. A geographical information system was used to examine the relationship between subbasin land uses and pesticide concentrations. Significant correlations were observed between in situ atrazine and diazinon concentrations and some subbasin land uses. Atrazine was significantly (P < 0.05) correlated to diazinon during some months. Of the 276 samples collected, 39% exceeded our experimentally derived diazinon LC(50) value, and 39% exceeded our minimum atrazine concentration of 5.0 microg/L. Results indicate the potential for increased toxicity from mixtures of compounds at environmentally realistic concentrations.