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La présente étude a été conduite pour apprécier le niveau de pollution des eaux du collecteur de
Dantokpa (Cotonou-Bénin) par l’évaluation de la diversité phytoplanctonique en relation avec les
caractéristiques physico-chimiques afin de faire ressortir le risque de leur rejet sans traitement dans la lagune de Cotonou. L’analyse des eaux usées préle...
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The present study was carried out monthly in four sites located in Najaf of Iraq at Al-Abasia River for the period from March 2012 to February 2013 included study some physiochemical properties of phytoplankton in order to study the quality and the quantity of phytoplankton and also the study includes the measurement of physical and chemical proper...
The present study was carried out monthly in four sites located in Najaf of Iraq at Al-Abasia River for the period from March 2012 to February 2013 included study some physiochemical properties of phytoplankton in order to study the quality and the quantity of phytoplankton and also the study includes the measurement of physical and chemical proper...
The present study was carried out monthly in four sites located in Najaf of Iraq at Al-Abasia River for the period from March 2012 to February 2013 included study some physiochemical properties of phytoplankton in order to study the quality and the quantity of phytoplankton and also the study includes the measurement of physical and chemical proper...
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... These low DO values are likely related to the degradation of a significant amount of POM in the lagoon (Figure 2e) that can originate, during the flood season, from several sources, such as the Ouémé deltaic plain, urban water drainage, or acadjas (i.e., traditionally made bamboo parks used by local fishermen to grow fish) [19,69]. The degradation of this POM, which consumes oxygen, was generally the main source of nutrients for rotifers [10,63,70,71] which may have increased rotifer diversity during the period of very low salinity and low DO concentrations during flooding. The composition and diversity of rotifers can also reflect a certain level of eutrophication in Nokoué Lagoon. ...
This study aimed to investigate the seasonal variation of zooplankton diversity and abundance in the Nokoué Lagoon in southern Benin. Through extensive sampling, a total of 109 zooplanktonic taxa were identified and quantified. The average zooplankton abundance was found to be 60 individuals per liter, with copepods and rotifers being the most dominant groups, comprising 68.1% and 29.1% of the total abundance, respectively. The key factor identified as driving the structure of the zooplanktonic assemblages was salinity, which showed significant seasonal variation. The results revealed that during the high water period, when the lagoon was filled with fresh water, rotifers were dominant, zooplanktonic diversity was highest, and abundances were quite high. Conversely, during the low water period, when the lagoon was characterized by brackish water, diversity was minimal, and abundance decreased slightly. The study also found that some areas of the lagoon showed high abundances independent of salinity levels, suggesting that other factors such as riverine inputs or the presence of acadjas (home-made brush parks used as fish traps) may also have notable effects on the zooplankton community. Overall, the findings of this study provide valuable insights into the functioning of one of the most biologically productive lagoons in West Africa.
... There have been studies about phytoplankton diversity in Benin (Adjahouinou et al. 2012;Akogbéto et al. 2019;Liady et al. 2020), none of them focused on mosquito breeding habitats. While previously published literature about gut contents provided information on phytoplankton species consumed by An. gambiae larvae, there were no published laboratory or field studies about the impact of phytoplankton on An. gambiae larvae. ...
The relationship between different species of phytoplankton and Anopheles gambiae mosquito larvae was studied in order to improve malaria control. Anopheles gambiae larval habitat was surveyed by sampling phytoplankton at 51 sites. The deleterious effect of Scenedesmus quadricauda on third instar larvae was evaluated in the laboratory. 27 phytoplankton species were encountered in the field survey. Anopheles gambiae larvae had a positive association with high densities of Spirogyra (Pearson chi-square = 25.56, P < 0.0001) and a negative association with high densities of green algae (Spirogyra, Elakotothrix, Coelastrum, Ankystrodesmus, Chlorella, Kirchneriella, Selanastrum, and Scenedesmus) and cyanobacteria (Oscillatoria, and Nostoc). Laboratory bioassays revealed that S. quadricauda is indigestible and toxic to An. gambiae larvae that ingest it. The larval mortality was 100% when larvae ingested only S. quadricauda and 85.6% if larvae were exposed to a mixture of S. quadricauda and cat food. The findings of this study indicate that phytoplankton management with S. quadricauda or other green algae offers a possible way to eliminate An. gambiae production. Complementary studies are needed to investigate the deleterious effect of these algae on An. gambiae under semi-natural and natural conditions.
... Urban and industrial effluents are, in most cases, major causes of ecological imbalance in continental ecosystems, besides wastewater discharges from agro-industrial companies, which are also of significant importance (Adjahouinou et al., 2012). This is the reality in most African countries where rivers are subject to physical and chemical disturbances resulting in an increased degradation of water quality (Taffouo et al., 2017), a change in the structure of settlements and decrease in biodiversity (Zé bazé Togouet, 2008;Onana et al., 2014). ...
In Cameroon, rivers are subjected to physicochemical disturbances, which increase the degradation of water quality. The aim of this study was to determine the spatio-temporal diversity of the phytoplankton groups and to evaluate the environmental parameters of the sampling sites in order to assess the quality of water in two hydrographic networks. Physicochemicals analyzes were carried out according to the standard methods while phytoplankton organisms were harvested by direct sampling and analyzed by the Utermöhl method. The analysis of Ammonia Nitrogen, Dissolved Oxygen, Electric Conductivity, Nitrates, Orthophosphates, pH, Temperature, and Turbidity.of water revealed the poor state of health of the water. Data from the Long Dry Season differed significantly (p < 0.05) from those recorded in other seasons. The phytoplankton communities were made up of Chlorophyta, Chrysophyta, Cyanophyta, and Euglenophyta with 11 classes dominated by Bacilliarophyceae (12 210 Ind/mL) and Cyanophyceae (6 208 Ind/mL). Phytoplankton densities were higher the Long Rainy Season and much lower in the Small Dry Season than in the Long Dry Season. Station near NODISCAM indicated significant organic pollution under the effect of agro-industrial discharges operating upstream of this company. For this station, the different values showed significant differences (p < 0.05) from one station to another. Finally, spatio-seasonal variations of phytoplankton densities showed logical responses to changes of physicochemical conditions in the environment. This work highlights the need to treat wastewater from collection channels before its dump into the natural environment, to prevent progressive eutrophication of the receiving aquatic environment, and poisoning by water consumption.
... But the Nokoué Lagoon, also bordered by 3 major urban centers (Cotonou, Abomey-Calavi, and Sémè Podji) totalizing more than 1.5 million inhabitants, is strongly impacted by various anthropogenic pollution sources. For instance, the lagoon is the receptacle of numerous urban drains and direct discharge by the surrounding populations of various wastes which has led to a deterioration of the water quality (Adjahouinou et al., 2012(Adjahouinou et al., , 2014Aina et al., 2012aAina et al., , 2012b. In addition, Nokoué Lagoon is also embedded within the 500 km long West African coastal water corridor that stretches from Lagos (Nigeria) to Accra (Ghana). ...
This study investigated the main water-level (WL) variability modes of Nokoué Lagoon in Benin (West-Africa). The average WL ranges between 1.3 and 2.3 m between the low- and high-water seasons. Seasonal as well as weak interannual variations between 2018 and 2019 are driven by rainfall regime over the catchment and associated river inflow. At sub-monthly scales, the lagoon is tidally choked: ocean tides can reach 90 cm, whereas in the lagoon semi-diurnal and diurnal tides hardly reach few centimeters. Choking conditions vary with river inflow and ocean tide amplitude, correctly represented by a simple tidal choking model. Diurnal modulation and asymmetry of the tide are stronger (weaker) during high (low) water period. We also observed WL variations of ±5–10 cm at a fortnightly frequency, stronger during wet (high-water) season. Superimposed on the seasonal, fortnightly and tidal WL variations, we further observed short-term high-frequency seiche events. Mostly observed during dry (low-water) conditions, they are characterized by typical standing-wave oscillations of 5–10 cm amplitudes and 3 h periods. They are forced by the passage of fast-moving squall-lines that induce strong wind variations, heavy rainfalls and rapid drop-off of the air temperature. Results obtained in this study provide useful metrics for the validation of flood forecasting models to be implemented in Benin, and elsewhere on the West African coastline.
... Seeding has been achieved by sampling 10 L of water from multi-culture (Clarias gariepinus and Oreochromis niloticus) pond and gently filtering it according to Agadjihouèdé et al. [16] by using a 25-µm plankton net in order to eliminate zooplankton, then the obtained filtrate was added to culture medium in each bucket for phytoplankton seeding. A fresh part has been used for observation and identification of phytoplankton species with photonic binocular microscope (BI 100; VWR International Belgium) and another 100 mL part was treated with formaldehyde 5% and concentrated 100 times for phytoplankton counting using a Neubauer counting cell under a photonic microscope [17]. Identification was carried out according to Adjahouinou et al. [17] from photographs realized at 10×, 40× and, 100× according to height and mobility of algae species and by using the identification keys of Bourrelly [18][19][20], Compère [21][22][23][24][25][26], Iltis [27], and Guiry et al. [28]. ...
... A fresh part has been used for observation and identification of phytoplankton species with photonic binocular microscope (BI 100; VWR International Belgium) and another 100 mL part was treated with formaldehyde 5% and concentrated 100 times for phytoplankton counting using a Neubauer counting cell under a photonic microscope [17]. Identification was carried out according to Adjahouinou et al. [17] from photographs realized at 10×, 40× and, 100× according to height and mobility of algae species and by using the identification keys of Bourrelly [18][19][20], Compère [21][22][23][24][25][26], Iltis [27], and Guiry et al. [28]. Algal density was estimated according to Boauli et al. [29] through the equation: D (cells/L) = × × 10 with M: mean algae cell number per rectangle of hematimeter, C: ...
... In addition, the analysis of phytoplankton classes in our culture media sets first Chlorophyceae, followed by Bacillariophyceae, Conjugatophyceae, Coscinodiscophyceae, and Euglenophyceae, which constitute predominant algae groups in fish farming ponds revealing nutrient availability. However, low densities of Euglenophyceae could be due to low organic load [17,27,29,49,50] but also consumption by zooplankton. Additionally, Chlorophyceae and Euglenophyceae are easily edible by many zooplankton, such as Cladocera, belonging to the Daphnia genus, as well as small zooplankton, such as rotifers [43,51]. ...
The current study aims at determining the optimal usage conditions of rabbit manure in a multispecies fresh water algae production for fish farming. This purpose, the experimental design is made of six treatments in triplicate including one control T0,
... The high values of phosphates are believed to come from domestic water discharges which are generally the main source of water pollution by phosphates. Domestic wastewater composed of detergents (used for dishwashing) is also a source of phosphates as well as urine [26]. Moreover, the high nitrate values, although obtained during the short dry season, could be due to domestic discharges of riparian populations into the lake, which enriches the environment. ...
This study aims to assess the phytoplankton community of Lake Ahémé, subject to
anthropogenic pressures. For this purpose, eight sites were sampled from September 2014 to October 2016. A total of 274 taxa were recorded and were mainly dominated by
Bacillariophyceae (54%), followed by Chlorophyceae (12.77%), Cyanophyceae
(10.22%), Euglenophyceae (9.49%), Conjugatophyceae (7.66%), Trebouxiophyceae
(2.18%), Dinophyceae (1.82%), Xanthophyceae (0.73%), Ulvophyceae (0.73%),
Chrysophyceae (0.36%). Overall, diversity was high during the long wet season and low
during the short dry season, with imbalanced distribution of phytoplankton taxa over the
study period. Biodiversity indices varied throughout seasons : between 4 and 16 for
Margalef index, between 1.2 and 3 bits for Shannon index, between 0.46 and 0.9 for
Simpson index, between 0.22 and 0.72 for Berger-Parker index and between 0.04 and
0.15 for evenness index. The particular abundance of diatoms observed is due to strong
mineralization of the lake at the time of the study. These observations suggest that
phytoplankton diversity and structure can be used in conjunction with physical and
chemical indicators to assess water quality.
... Lake Ahémé is mainly characterized by three groups of diatoms species (abundant, common, rare). Species such as Nitzschia reversa, Nitzschia sigma, Craticula cuspidata, Gyrosigma acuminatum and Aulacoseira granulata are a typical component of tropical environments (Koffi and Philippe 2009;Ikenweiwe, Davies, and Idowu 2011;Adjahouinou, Liady, and Fiogbe 2012;Atanlé et al. 2013;Dimowo 2013;Radji et al. 2013;Issifou et al. 2014;Annang et al. 2014;Seu-Anoi et al. 2014;Houssou et al. 2016;Tian et al. 2017;Zeng et al. 2017). Cerataulina bicornis (12.0 %), Entomoneis paludosa (30.9 %), Entomoneis sp. ...
... Ce qui pourrait se justifier par les températures relativement élevées (28,76°C à 29,55°C) dans les différents bassins, accompagnées de pH alcalins (9,36 à 10,23) (Merghem et al., 2016). Cependant, des valeurs de conductivité supérieures à 200 μS/cm (conductivité de l'eau douce) peuvent être attribuées à la présence d'éléments dissouts (Laniel M., 2013) dans le milieu notamment les nutriments qui seraient contenus dans les eaux usées provenant des différents services des centres hospitaliers (Guiral et al., 1993 ;Adjahouinou et al.,2012). ...
The quality of the phytoplankton community in the basins that composed a microphyte natural lagoon station gives an indication on its proper functioning. So, the algal flora of water from three (3) basins of the wastewater treatment station of the Regional Hospital Center of Daloa (Côte d’Ivoire) was inventoried, using water samples taken from each basin. The phytoplankton of the different samples were observed under an optical microscope. Similarly, the component of phytoplankton, the density and the planktonic index of each basin were determined. It’s appeared that the community of phytoplankton from the basins was estimated at 63 taxa grouped into 8 classes, 5 phyla. The Cyanobacteria and Chlorophyceae are more diversified. The planktonic index showed that the basins are under an eutrophic state due to a high density of Cyanobacteria, which are indicators of pollution during the study period. In addition, the results revealed a similarity between the basins about the phytoplankton flora inventoried. But, this similarity is more marked (76.1%) between the anaerobic basin (basin 1) and the maturation or aerobic basin (basin 3). This is contrary to the normal functioning of the wastewater treatment station.
La qualité du peuplement du phytoplancton au sein des bassins qui composent une station de type lagunage naturel à microphytes donne une indication sur son efficacité. Ainsi, la flore algale des eaux issues des trois (3) bassins de la station d’épuration des eaux usées du centre hospitalier régional de Daloa (Côte d’Ivoire), a été inventoriée grâce à des échantillons d’eau prélevés dans chaque bassin. Le phytoplancton des différents échantillons a été observé au microscope optique. De même, la composition du phytoplancton ainsi que la densité et l’indice planctonique de chacun des bassins ont été déterminés. Il ressort que la communauté phytoplanctonique des eaux issues des bassins est estimée à 63 taxons regroupés en 8 classes, 5 embranchements. Parmi ces 63 taxons, les Cyanophycées et les Chlorophycées sont plus diversifiées. L’indice planctonique a montré que les bassins sont dans un état eutrophe dû à une forte densité des Cyanobactéries au cours de la période d’étude. Par ailleurs, les résultats ont révélé une ressemblance entre la flore phytoplanctonique inventoriée dans chaque bassin, mais cette ressemblance est encore plus marquée entre le bassin anaérobie (bassin 1) et le bassin de maturation ou aérobie (bassin 3) avec un taux de 76,1 %. Ce qui est contraire au fonctionnement normal de la station.
... Quatre séances d'échantillonnage ont été effectuées suivant le rythme climatique et aux environs de la mijournée où la transparence des eaux est maximale afin de maximiser la récolte de ces organismes [12]. Cet échantillonnage a été effectué à l'aide d'un filet à plancton de 25µm de vide de maille, traîné sur quelques dizaines de mètres puis de bas vers le haut, en vue d'explorer à la fois la diversité horizontale et verticale du peuplement phytoplanctonique. ...
Le présent travail a été conduit pour étudier la diversité phytoplanctonique de la lagune de Porto-Novo et identifier les espèces bioindicatrices de l'eutrophisation à partir de l'établissement de son degré de pollution. L'analyse des eaux prélevées au niveau de chacun des quinze sites a révélé des teneurs élevés de la DBO 5 et du phosphore total, une forte conductivité électrique et un faible taux d'oxygène dissous. L'analyse du phytoplancton au microscope et sur la base des clés d'identification a permis d'identifier au total 170 espèces phytoplanctoniques au sein de diverses familles. Cette communauté hétérogène de phytoplancton se répartit en cinq embranchements (Cyanophytes, Chlorophytes, Chrysophytes, Euglénophytes et Rhodophytes) et neuf classes dominées par les Diatomophycées et les Euglénophycées. Cette lagune est eutrophe d'après les indices de Nygaard. Coscinodiscus granii, C. asteromphalus, C. radius, Surrirella atomus, Navicula nungaensis, Aulacoseira granulata, Euglena sp, Pandorina morum et P. sp sont les espèces bioindicatrices qui tolèrent l'état d'eutrophisation de la lagune. Il est donc nécessaire de prendre des mesures pour limiter l'apport en nutriments eutrophogènes dans cette lagune afin de préserver la vie aquatique. Mots-clés : eutrophisation, indices de Nygaard, diversité phytoplanctonique, espèces bioindicatrices. Abstract Eutrophication degree and phytoplankton diversity of Porto-Novo lagoon, Benin Republic The present work was conducted to study the phytoplankton diversity of the lagoon under investigation, and to identify the bio-indicating species signalling eutrophication from the establishment of its degree of pollution. Analysis of the water collected at each of the fifteen sites revealed high levels of BOD5 and total phosphorus, high electrical conductivity and low dissolved oxygen. Phytoplankton analysis under an binocular microscope and using appropriate keys made it possible to identify a total of 170 phytoplankton species in various families. This heterogeneous community is distributed through 5 division of phytoplankton taxa (Cyanophyta, Chlorophyta, Euglenophyta, Rhodophyta, Chrysophyta) and 9 class dominated by 43 Afrique SCIENCE 14(3) (2018) 42-57 Henri Kpèdékpo AKOGBETO et al. Diatomophyceae and Euglenophyceae. This lagoon is eutrophic according to the Nygaard indices. Coscinodiscus granii, C. asteromphalus, C. radius, Surrirella atomus, Navicula nungaensis, Aulacoseira granulata, Euglena sp, Pandorina morum et P. sp are the bioindicators species that tolerate the eutrophication state of the lagoon. It is therefore necessary to take measures to limit the intake of eutrophogenic nutrients in this lagoon in order to preserve aquatic life.
... However, it is important to note 530 that no study has thoroughly monitored the annual 531 distribution of this taxon in the lake. The available studies 532 cover the water recession period (Goussanou, 2012) and 533 part of the low-water period (Adjahouinou et al., 2012). For 534 these periods, four (4) main classes of algae have been 535 ...
... Euglenophyceae (15 species) and Cyanophyceae (11 spe-538 cies) (Goussanou, 2012;Adjahouinou et al., 2012). 539 ...
... The west of the Lake, near Ganvié 548 and the Djonou River, presents the highest taxonomic 549 diversity of 36 species followed by the centre of the Lake 550 about 29 species. The most numerous species were: 551 Navicula bacillum, Synedra ulna, Oscillatoria granulate (all 552 found almost everywhere in the Lake) and Euglena 553 spirogyra (mostly found in the west of the Lake) 554 (Goussanou, 2012;Adjahouinou et al., 2012). Diatomophyceae and Euglenophyceae were respective-558 ly the most abundant classes, followed by Cyanophyceae 559 ...
A systematic literature review was undertaken to understand the state and relationship between habitat types and biodiversity in the open coastal Lake Nokoué and to analyse the research gaps towards an efficient management of this ecosystem. Habitat types in Lake Nokoué have been profoundly impacted by the urbanisation around the lake. Kilometres of riparian habitat including mangrove vegetation were destroyed on the south and western shoreline of the lake, removing the natural protection of the ecosystem to the increasing sewage nutrient load. In addition, to this anthropogenic pressure, the solid wastes from the villages on stilts (Ganvié’s villages) increased the nutrient enrichment of the lake. Consequently, the lake experience a seasonal bloom of water hyacinth which dies and sinks to its bottom each year when the salinity rises above 6 ppt. Note that the salinity dynamics of the lake is governed by its hydrological regime which was highly affected by the widening of the sea entrance into the lake around 1960. In addition to these changes, the intensification of the acadja fishing practice has led to the exportation of tonnes of dry woods into the lake. The decay of these woods combined with the accumulation of hyacinth detritus has disturbed the habitats of macroinvertebrates and fish. There is a progressive shift in the system from freshwater species to marine water species and from insectivorous fish to detritivorous fish. Management solutions required reduction of both detritus accumulation and external nutrient load. © 2018 European Regional Centre for Ecohydrology of the Polish Academy of Sciences
