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Larval Types and Early Postlarval Biology of Naiads (Unionoida)
Abstract
In freshwater bivalves development takes place in three ways (Fig. 6.1).
1.
By producing veliger larvae as in Dreissena polymorpha, which is particularly successful wherever it first appears.
2.
By releasing fully developed young mussels from brood pouches (viviparity) as in Sphaeriidae.
3.
By passing early development as a parasitic stage on a host as in naiads (Unionoida).
... Unionids acquired the capacity to attach to a fish host to travel along the fluvial ecosystems, with a few species employing amphibians instead of fish (Wächtler, Dreher-Mansur & Richter, 2001). In addition to this dispersal, this interaction between freshwater mussel larvae and the fish host is regarded as a parasitic strategy for nutrition and protection, which allow the larvae to grow isolated from the external medium and metamorphose into juvenile mussels (Barnhart, Haag & Roston, 2008;Denic, Taeubert & Geist, 2015;Schwartz & Dimock, 2001;Skawina, 2021). ...
... Based on the large diversity among freshwater mussels, multiple studies reported a fantastic array of morphological adaptations and strategies to cope with this compulsory parasitic travel. Two main different larval types are described among unionids, the lasidium, restricted to approximately only 86 species of Etherioidea superfamily located in the southern hemisphere, and the glochidium, the most common larval type of unionids (Skawina, 2021;Strayer, 2008;Wächtler et al., 2001). Figure 2. Macroscopical and histological appearance of a gravid freshwater mussel (Anodonta anatina). ...
... At these late stages, the juvenile mussels achieved a marked size in the gills around 400 µm (see Section 1.4) before detaching from the fish to bury in the riverbed. Very few studies focused on the detachment from the gills, only describing signs of "opening up" of the gill epithelium surrounding the juveniles by SEM (Scharsack, 1994;Wächtler et al., 2001). As reported in other glochidiosis, there is little information about how the gills recover from the infestation, only describing a partial repairment after 50 days, when farmed salmon were transferred int to saltwater (Treasurer & Turnbull, 2000). ...
This Ph.D. Thesis arose with the aim to understand and provide solutions for culturing the endangered Freshwater Pearl Mussel during its parasitic stage in the Atlantic salmon. To optimize the production of young mussels and preserve fish
health, the morphopathological pattern of glochidiosis was characterized during the early and late stages of glochidiosis and related to the larval development and metamorphosis of Margaritifera margaritifera, from glochidium to post-larva. The
results here enclosed contribute to a better understanding of the pathogenesis of glochidiosis that may aid to manage the parasitic stage during the culture of freshwater mussels.
... Морфологию глохидиев анодонт (включая сведенные в синонимы с Anodonta виды рода Colletopterum) достаточно подробно изучали как с помощью светового, так и сканирующего электронного микроскопов [Жадин, 1938;Антонова, 1986, 1987Антонова, Старобогатов, 1988, 1989Саенко, 2001, 2006, 2014а, 2014б, 2019Harms, 1909;Giusti et al., 1975;Nagel, 1985;Niemeyer, 1993;Pekkarinen, Englund, 1995;Hoggarth, 1999;Wächtler et al., 2001;Lima et al., 2006;и др.]. Глохидии представителей рода крупные, не менее 300 мкм в длину, при этом длина глохидиальной створки, как правило, чуть больше, реже равна ее высоте; длина крючка от 114 мкм [Антонова, 1986, 1987Саенко, 2001, 2006Wood, 1974;Giusti et al., 1975;Hoggarth, 1999;Wächtler et al., 2001;Lopes-Lima et al., 2016]. ...
... Морфологию глохидиев анодонт (включая сведенные в синонимы с Anodonta виды рода Colletopterum) достаточно подробно изучали как с помощью светового, так и сканирующего электронного микроскопов [Жадин, 1938;Антонова, 1986, 1987Антонова, Старобогатов, 1988, 1989Саенко, 2001, 2006, 2014а, 2014б, 2019Harms, 1909;Giusti et al., 1975;Nagel, 1985;Niemeyer, 1993;Pekkarinen, Englund, 1995;Hoggarth, 1999;Wächtler et al., 2001;Lima et al., 2006;и др.]. Глохидии представителей рода крупные, не менее 300 мкм в длину, при этом длина глохидиальной створки, как правило, чуть больше, реже равна ее высоте; длина крючка от 114 мкм [Антонова, 1986, 1987Саенко, 2001, 2006Wood, 1974;Giusti et al., 1975;Hoggarth, 1999;Wächtler et al., 2001;Lopes-Lima et al., 2016]. Самые крупные глохидии A. anatina отмечены в Португалии, где зрелые личинки Lima et al., 2016], однако основная часть изученных европейских и сибирских популяций вида не превышала 380 мкм [Саенко, 2001, 2006Niemeyer, 1993;Pekkarinen, Englund, 1995;Hoggarth, Рис. 3. Микроскульптура наружной поверхности створок глохидиев Anodonta anatina: А, Bближе к вентральному участку створки; C, D -в центральной части створки (район аддуктора); E, F -у лигамента. ...
Приводятся первые сведения по морфологии глохидиев беззубки Anodonta anatina (L., 1758) (Bivalvia, Anodontinae) из р. Карасу Национального парка «Самурский» Республики Дагестан. Ключевые слова: двустворчатые моллюски, Anodonta anatina (L., 1758), глохидии, Дагестан.
... Jumlah larva yang ditemukan dalam marsupial kerang kijing di Sungai Lahumbuti berkisar 16317-58429 ekor. Jumlah ini relatif jauh berbeda dengan jumlah larva kerang Anodonta cygnea yang dapat berkisar 13378-235592 (Başçınar dan Düzgüneş, 2009), bahkan sangat jauh berbeda pada kerang sama (Anodonta cygnea) yang mencapai 3,1-3,7x10 5 (Wächtler et al., 2001). Jumlah larva ini jauh berbeda atau lebih tinggi bila dibandingkan dengan kerang air tawar lainnya yaitu: Unio tumidiformis berkisar 1500-15.000 ...
Mussel mussels are invasive shellfish whose reproductive potential in the Lahumbuti River is unknown. This study aims to determine the seasonal variations in the reproduction of mussel shells in the Lahumbuti River, Southeast Sulawesi. This research was carried out in the Lahumbuti River Konawe, Southeast Sulawesi in 2 periods, namely: May-October 2021 and February-June 2022. The mussels were collected manually using a hand scoop. Furthermore, the shells are washed from dirt/soil attached to the shell. The length and weight of the mussels (total weight and meat weight) were measured using a caliper and a digital scale with an accuracy of 0.5 mm and 0.01 g, respectively. TKG was observed microscopically by using a gonad microscope. Fecundity was calculated by the number of type D spats in the mussel gill sieves. The results showed that male and female mussels were in developmental phases (TKG I, II and III), gonadal maturity (TKG IV) and spawning (TKG V) were found throughout the season. The actual IKG values did not differ based on the time of observation, although there was a tendency for the IKG values to be found to be higher in February-April. Fecundity of mussel mussels ranged from 16317-58429. The size at first maturity of male and female mussel mussels occurred at 3.9 cm and 4.7 cm, respectively.
... The survival rate of glochidia and juvenile mussels is relatively low, so the rates of fecundity are an important trait for the persistence of freshwater mussels (Bauer & Wächtler, 2001;Wu et al., 2018;Liu et al., 2022). Fecundities vary widely among freshwater mussel species (Wächtler, Drehermansur & Richter, 2001;Wu et al., 2018). For example, for Chinese mussel species fecundity ranged from 7,800 glochidia per brood in A. arcaeformis to 1,715,000 glochidia per brood in S. oleivora . ...
Freshwater mussels are one of the most diverse and endangered faunas worldwide. Owing to the continuing global biodiversity loss, it is essential to identify and protect populations that are not severely affected by human disturbances and ensure that natural genetic diversity is not inevitably lost. The generation of baseline genetic diversity data will help guide species conservation and restoration plans in the Yangtze River Basin where freshwater mussels are facing multiple threats and where strong declines have been observed.
The genetic diversity of freshwater mussels was assessed using 818 mtDNA cytochrome c oxidase subunit 1 (COI), 565 28S rRNA and 509 COI + 28S datasets, and refuge areas in the Yangtze River floodplain were predicted using a Maxent habitat suitability model.
The results showed that the genetic diversity of Aculamprotula spp., Sinosolenaia carinata , Cuneopsis rufescens , Lamprotula cornuumlunae , Lanceolaria lanceolata , Ptychorhynchus pfisteri , Schistodesmus spp. and Sinohyriopsis cumingii was lower than that of other freshwater mussels, which indicated that the conservation status of these species should be prioritized.
The habitat suitability modelling showed that Poyang Lake and Dongting Lake basins (lakes and tributary rivers connected to the Yangtze River mainstem) present the most suitable habitats for freshwater mussels, indicating that lateral hydrological connectivity may be the most important factor in maintaining the genetic diversity of Chinese freshwater mussels. Consequently, Poyang Lake and Dongting Lake basins should be established as protected areas.
This study provides valuable information for the conservation and management of freshwater mussel biodiversity in the Yangtze River basin, which will not only help conserve this vulnerable group but will also provide wider benefits to freshwater ecosystems.
Global increase in aquaculture production has created a need to reduce its environmental impacts. Nutrients could be recycled especially at land-based recirculating aquaculture systems (RAS) by cultivating green microalgae in aquaculture effluent. However, microalgae are difficult to harvest. As a multi-trophic solution, mussels could be used in harvesting microalgae. We tested three European freshwater mussels (duck mussel Anodonta anatina, swan mussel A. cygnea, and swollen river mussel Unio tumidus) for filtering two common green microalgae (Monoraphidium griffithii and Selenastrum sp.) grown in RAS effluent. Mussels decreased microalgal concentrations in the tanks 42–83% over three consecutive trials. Algal concentrations at the end of each trial were lowest for both microalgae in tanks containing Anodonta mussels. Clearance rates were higher for Anodonta mussels than for U. tumidus. Mussels biodeposited more microalgae to tank bottoms when M. griffithii was filtered. Ammonium concentration decreased or did not change in tanks with M. griffithii, but increased in tanks containing Selenastrum sp. These results suggest that of the tested species Anodonta mussels and M. griffithii show best potential for RAS effluent bioremediation application. We conclude that a co-culture of microalgae and unionid mussels could be used for recycling nutrients in aquaculture.
In this review, we synthesize the current knowledge of the biology, ecology, and impact of Sinanodonta freshwater mussels (Bivalvia, Unionidae), native to East Asia, that have successfully invaded Europe, Central America, North Africa, and several Asian regions. The main introduction pathways of Sinanodonta were reconstructed based on DNA sequence data and distribution records. We show that invasive lineages of Sinanodonta belong to three species, namely, S. woodiana s. str. (“temperate invasive” lineage), S. pacifica (“tropical invasive” lineage), and S. lauta. Their generalist fish-dispersed larvae, short life span, high fecundity, use by humans for multiple purposes, and ability to establish populations in anthropogenically disturbed conditions were identified as crucial traits driving their invasions. Information on the consequences is scarcer, but Sinanodonta can impact native species through larval parasitism, host fish/food competition, and parasite transmission. In addition, ecosystem effects through their filtration—biodeposition—excretion activity and the occurrence of massive die-offs were detected. Ecosystem services and disservices have not yet been quantified, even at local scales, and management methods in the invasive range are understudied. A better understanding of Sinanodonta ecology, impacts, and management options is urgently needed to make informed decisions and set realistic and impactful restoration goals.
Successful aquatic biological invasions are often dependent on human vectors. The Chinese pond mussel Sinanodonta woodiana is a fast-growing , high-filtering, and highly fecund unionid bivalve that has expanded rapidly throughout Europe in the last several decades. Human-mediated vectors such as fish aquaculture and pet shop trade are believed to be primary drivers of the mussel's spread, but the specific dispersal pathways of S. woodiana remain unclear. We analyzed eleven microsatellites in 245 S. woodiana individuals from seven wild populations and three pet shops to assess genetic relatedness potential sources, and dispersal pathways of S. woodi-ana in Bavaria, Germany. Wild populations shared a single mitochondrial haplotype present in all Euro-pean populations and shop-sourced individuals were genetically similar to wild populations. Only one wild population was structurally different than all other populations, which may be explained by its dispersal trajectory. Our results provide the first genetically informed insights into S. woodiana dispersal in the context of human activity. We underscore the value of genetic tools in invasive species management, which can uncover patterns of dispersal even on local scales.
Freshwater mussels of the genus Buldowskia (Bivalvia, Unionidae) are distributed from the Amur River basin in Russia and China southward to the Korean Peninsula and some Japanese islands. This work is an integrative morphological study of Buldowskia suifunica glochidia from locations in the Primorsky Territory, the Russian Far East. Glochidia of B. suifunica, taken from the same gill have asynchronous development. The external and internal morphology of its shell has been characterized. The morphology of its sensory system, within three stages of larval development (immature, intermediate and mature glochidia), consists of hair cells as well as nonhair cells. Their muscle system is composed of massive adductor and minor muscle bundles. The FMRFamid-ergic nervous system turned out to be a complex system includes basal cells (neurons), their neurites and anterior neurons. FMRFamide and tubulin was found in all neurons. Glochidia of B. suifunica have only four 5-HT-lir neurons. We concluded that B. suifunica glochidial nervous system differs from those of the larval systems of planktotrophic marine mollusks.
Unionoids are in global decline, which may be associated with their complex life cycle. Their juveniles are unique because while hidden (burrowed deeply in bottom sediments) they undergo critical anatomical changes (also developing a characteristic juvenile shell sculpture). Currently, the juveniles’ period of life is believed to be both the least known and one of the most vulnerable—thus the possibility of obtaining any biological knowledge is essential for establishing conservation strategies and addressing functional or evolutionary questions. I propose two new methods for visualization of the burrowing behavior of unionoid juveniles within deposits that are cheap and easy: (1) laminated deposits of quartz–aragonite sand for time-stepped X-ray images of bivalve traces, and (2) silica gel serving as 'invisible sand' for direct observations and video recording of behavior within sediments. Both deposits in a pilot study were accepted by the juvenile unionoids—they were stable enough and penetrable, with no observable signs of harmful effects on animals’ behavior during trials. In both, juveniles were clearly visible, settled within the top 1 cm layer of deposits. Both methods are promising tools for future in situ within the deposits research on the biology of this much unexplored and vulnerable unionoids' life stage.
The different phases of the biological cycle of Anodonta cygnea L. living in lake Trasimeno (Central Italy) are described in the present paper. Researches have been carried out on histological sections of germinal tissues and gills of specimens of both sexes sacrificed every month and verified by following the course of the parasitic phase of life of glochidia on the fish of the lake. Moreover, the various species of fish heavily infested by glochidia have been identified and the glochidium infestation frequency has been determined. The structure of the glochidium shell has been studied with the scanning microscope for a better understanding of the mechanism of attachment to fish and to collect more information in order to compare the species of Anodonta from lake Trasimeno with those of other parts of Europe.
Fish hosts of the glochidial larval stages of nine species of mussels are reported from Texas. These include two species of Lampsilis and one species each of Pyganodon, Utterbackia, Anodonta, Arcidens, Tritogonia, Quadrula and Cyrtonaias.
The glochidia dissected from the marsupial gills of Margaritifera margaritifera (L.) collected from the River Ahtavanjoki in western Finland were studied using light microscopy, scanning and transmission electron microscopy (SEM and TEM). The glochidial shells had a mean length of 69 μm and a mean height of 77μm. The periostracum-covered shell valves were non- pitted and very thin, kept together by a small adductor muscle. The shells had no hooks or spines; the attachment to a host fish may be tightened by fluid-filled periostracal flanges, which turn inside from the shell edges. The inner periostracum of the flange originated from a groove near the margin of the larval mantle. No larval thread was discovered. There were only two pairs of sensory hair tufts located ventrally, and a few cilia occurred at the centre of the glochidium. The foot rudiment was equipped with long cilia, and the lateral pits harboured shorter cilia. The mantle comprised two layers and an intrapallial cavity between them. The mantle cells had large granules, which showed both basophilia and acidopbilia, and the inner mantle cells had long microvilli projecting towards the mantle cavity. The extensive mantle may be multifunctional serving in absorption and digestion of nutrients, excretion, respiration and regulation of salt and water. The thin shell may also allow gaseous exchange but also may offer a route for entry of harmful substances, such as protons from acidified water.
Freshwater mussels (Unionidae) are one of the most rapidly declining faunal groups in North America. Among the 52 recognized taxa in Texas, at least 42 have been reported in or near the Big Thicket Region of eastern Texas (Sulphur River to Buffalo Bayou drainages). Current findings indicate in some areas of eastern Texas several unionid species have maintained significant populations and continue to support commercial and sport fisheries. However, other taxa have become extremely rare and several have not been seen alive in the past 10 to 15 years. Nine species have been considered to be threatened, endangered, or of special concern by the American Fisheries Society. Population declines regionally typically reflect both aquatic and terrestrial habitat modification and degradation, historical and current pollution, and wide-ranging human development. Currently known status of mussel species and river systems is summarized herein.
The freshwater mussel Anodonta woodiana is native to eastern Asia. In recent years, it was discovered in fish hatcheries in Romania, Hungary, France, and several Indonesian islands. It also was collected in the wild in the Dominican Republic and Costa Rica. These occurrences are believed to be the result of the incidental introduction of exotic fishes imported for food, as foraging fishes, or for mosquito control, which bore parasitic glochidia of the mussel. These hosts are grass, common, bighead, and silver carp; Nile tilapia; and mosquitofish. Because these fishes are imported throughout the world, Anodonta woodiana may eventually be found in additional countries. It has the potential to escape and compete with native freshwater mussels wherever it is introduced.