BIVALVE MOLLUSCS (BIVALVIA: UNIONIDAE, DREISSENIDAE, SPHAERIIDAE) OF UDMURTIA

The results of the studies of fauna of bivalve molluscs of Udmurt Republic are summarized. The annotated check-list of species of bivalve molluscs of the waterbodies of Udmurtiya is presented. After examination of own collections and critical assessment of published data, 26 species of bivalves from 74 localities (14 rivers, 2 reservoirs, 8 pounds and 2 oxbow lakes) have been included into the final list. In studied region 11 species of bivalves are recorded for the first time. From the zoogeographical point of view most species belong to the European-Siberian faunistic group (46 %), also a considerable part of fauna are European species (26,9% of overall species composition), which are located in the region at the Eastern border of the range.

The Common Sunstar Crossaster papposus—A Neurotoxic Starfish

Saxitoxins (STXs) are a family of potent neurotoxins produced naturally by certain species of phytoplankton and cyanobacteria which are extremely toxic to mammalian nervous systems. The accumulation of STXs in bivalve molluscs can significantly impact animal and human health. Recent work conducted in the North Sea highlighted the widespread presence of various saxitoxins in a range of benthic organisms, with the common sunstar (Crossaster papposus) demonstrating high concentrations of saxitoxins. In this study, an extensive sampling program was undertaken across multiple seas surrounding the UK, with 146 starfish and 5 brittlestars of multiple species analysed for STXs. All the common sunstars analysed (n > 70) contained quantifiable levels of STXs, with the total concentrations ranging from 99 to 11,245 µg STX eq/kg. The common sunstars were statistically different in terms of toxin loading to all the other starfish species tested. Two distinct toxic profiles were observed in sunstars, a decarbomylsaxitoxin (dcSTX)-dominant profile which encompassed samples from most of the UK coast and an STX and gonyautoxin2 (GTX2) profile from the North Yorkshire coast of England. Compartmentalisation studies demonstrated that the female gonads exhibited the highest toxin concentrations of all the individual organs tested, with concentrations >40,000 µg STX eq/kg in one sample. All the sunstars, male or female, exhibited the presence of STXs in the skin, digestive glands and gonads. This study highlights that the common sunstar ubiquitously contains STXs, independent of the geographical location around the UK and often at concentrations many times higher than the current regulatory limits for STXs in molluscs; therefore, the common sunstar should be considered toxic hereafter.

Calibrating phylogenies assuming bifurcation or budding alters inferred macroevolutionary dynamics in a densely sampled phylogeny of bivalve families

Analyses of evolutionary dynamics depend on how phylogenetic data are time-scaled. Most analyses of extant taxa assume a purely bifurcating model, where nodes are calibrated using the daughter lineage with the older first occurrence in the fossil record. This contrasts with budding, where nodes are calibrated using the younger first occurrence. Here, we use the extensive fossil record of bivalve molluscs for a large-scale evaluation of how branching models affect macroevolutionary analyses. We time-calibrated 91% of nodes, ranging in age from 2.59 to 485 Ma, in a phylogeny of 97 extant bivalve families. Allowing budding-based calibrations minimizes conflict between the tree and observed fossil record, and reduces the summed duration of inferred ‘ghost lineages’ from 6.76 billion years (Gyr; bifurcating model) to 1.00 Gyr (budding). Adding 31 extinct paraphyletic families raises ghost lineage totals to 7.86 Gyr (bifurcating) and 1.92 Gyr (budding), but incorporates more information to date divergences between lineages. Macroevolutionary analyses under a bifurcating model conflict with other palaeontological evidence on the magnitude of the end-Palaeozoic extinction, and strongly reduce Cenozoic diversification. Consideration of different branching models is essential when node-calibrating phylogenies, and for a major clade with a robust fossil record, a budding model appears more appropriate.

Studies on New Zealand Bivalve Larvae, with Observations on the Adults, and on the Hydrology of Bay of Islands and Wellington Harbour

<p>1) Observations made on some hydrological parameters at Bay of Islands and Wellington Harbour during 1970-71 are presented and discussed. The parameters include water temperature, salinity, dissolved oxygen content and turbidity. The water current system in Bay of Islands is also discussed and a proposed pattern presented. The hydrology of Bay of Islands and Wellington Harbour are compared. Bay of Islands is topographically lees isolated from oceanic influence than Wellington Harbour, and there is a more marked change from estuarine to oceanic hydrological conditions within the bay. Monthly mean surface seawater tempe ratures at Bay of Islands exceed those of Wellington Harbour by about 4 degrees C. Water temperature stratification is more marked in Bay of Islands than Wellington Harbour, suggesting less efficient water mixing. Salinities are lower in Wellington harbour (normally about 33.5 - 34.5 parts per thousand) than the main basin of Bay of Islands (normally about 3S.5. parts per thousand). Turbidities in estuarine areas of Bay of Islands are similar to those for most of Wellington Harbour ( 3 - 6 metres Secchi Disc visibility values), but are much Less in outer basin areas (Secchi Disc visibility values may exceed 15 metres). Dissolved oxygen content is high in both harbours, frequently exceeding 100 per cent saturation in surface water. The results suggest that although both harbours are hydrologically quite homogeneous, Wellington Harbour is more efficiently mixed than Bay of Islands. (2) Benthic and shore collections of marine bivalve molluscs were made in Bay of Islands, and benthic collections were made in Wellington Harbour, during 1970-72. The species occurring are recorded and discussed, and the distribution of some common species in Wellington Harbour is related to sediment types. A list of bivalve molluscs collected in Bay of Islands is presented, and additional species to previous Wellington Harbour species lists are recorded. Invertebrate marine communities described for New Zealand are discussed, and the bivalve fauna of both harbours is visually compared to these communities. The observations at fifty four anchor dredge benthic stations in Wellington Harbour are then treated statistically, and compared to the visual assessments. It appears that the great variability in Wellington Harbour sediments makes identity of classical communities in the harbour almost impossible. However, station groups (groups of stations with similar bivalve species present) are evident, and their distribution in Wellington Harbour correlate closely to sediment type distribution. Lists of the most abundant bivalve species occurring in both harbours, deduced from all the observations presented in this study, are given. (3) Observations were made on the occurrence of common late stage bivalve larvae in the plankton at Bay of Islands and Wellington Harbour during 1979 - 71. Three stations in Bay of Islands and four stations in Wellington Harbour were sampled approximately monthly. The bivalve larvae in shorter series of plankton samples from Raumati Beach, Dargaville Beach, Mahurangi, Ohiwa Harbour, Raglan Harbour and Kaipara Harbour during 1971 - 72 were also analysed. Twenty-nine species of bivalve larvae from these plankton samples are described. Twenty-three species of late stage bivalve larvae are provisionally identified, the identifications being based on the larval hinge structure, the distribution and abundance of the larvae in relation to adult stocks, and in some cases by correlation with the adult gonad or condition index cycle. The broad seasonal pattern of occurrence of twenty five species of late stage bivalve larvae in the plankton at Bay of Islands, Wellington Harbour and Raumati Beach is presented. (4) Ecological studies made on bivalve larvae at Bay of Islands and Wellington Harbour during 1970 - 71, are presented and compared to other published studies from overseas. Included are observations on the vertical meso-distribution of bivalve larvae over tidal cycles in estuarine and non-estuarine localities of l2m to l5m depth, the daytime vertical meso-distribution of bivalve larvae in non-estuarine water 20m- 30m in depth, the effect of light on the vertical meso-distribution of bivalve larvae in water 15m- 30min depth, and the horizontal mega-distribution of bivalve larvae in Wellington Harbour and Bay of Islands. The observations suggest that in estuarine areas, the effect of alternating tides on the vertical distribution of bivalve larvae far outweighs the effects of any other factors. During the flood tide, bivalve larvae rise from the bottom into the water column and are carried up the estuary by the tide. During the ebb tide the larvae settle and remain on the bottom. In non-estuarine areas, no such vertical migration was observed. Gravity, light and water currents, in particular, affect the vertical distribution of bivalve larvae in these areas. The horizontal mega-distribution of bivalve larvae within Wellington Harbour is fairly uniform. In Bay of Islands, bivalve larvae occur in greatest densities near the shores, while much of the central basin is almost devoid of larvae. This distribution is due to the proximity of the adult stocks to the regions of most larvae, and to the prevailing water current pattern within the bay.</p>

Studies on New Zealand Bivalve Larvae, with Observations on the Adults, and on the Hydrology of Bay of Islands and Wellington Harbour

<p>1) Observations made on some hydrological parameters at Bay of Islands and Wellington Harbour during 1970-71 are presented and discussed. The parameters include water temperature, salinity, dissolved oxygen content and turbidity. The water current system in Bay of Islands is also discussed and a proposed pattern presented. The hydrology of Bay of Islands and Wellington Harbour are compared. Bay of Islands is topographically lees isolated from oceanic influence than Wellington Harbour, and there is a more marked change from estuarine to oceanic hydrological conditions within the bay. Monthly mean surface seawater tempe ratures at Bay of Islands exceed those of Wellington Harbour by about 4 degrees C. Water temperature stratification is more marked in Bay of Islands than Wellington Harbour, suggesting less efficient water mixing. Salinities are lower in Wellington harbour (normally about 33.5 - 34.5 parts per thousand) than the main basin of Bay of Islands (normally about 3S.5. parts per thousand). Turbidities in estuarine areas of Bay of Islands are similar to those for most of Wellington Harbour ( 3 - 6 metres Secchi Disc visibility values), but are much Less in outer basin areas (Secchi Disc visibility values may exceed 15 metres). Dissolved oxygen content is high in both harbours, frequently exceeding 100 per cent saturation in surface water. The results suggest that although both harbours are hydrologically quite homogeneous, Wellington Harbour is more efficiently mixed than Bay of Islands. (2) Benthic and shore collections of marine bivalve molluscs were made in Bay of Islands, and benthic collections were made in Wellington Harbour, during 1970-72. The species occurring are recorded and discussed, and the distribution of some common species in Wellington Harbour is related to sediment types. A list of bivalve molluscs collected in Bay of Islands is presented, and additional species to previous Wellington Harbour species lists are recorded. Invertebrate marine communities described for New Zealand are discussed, and the bivalve fauna of both harbours is visually compared to these communities. The observations at fifty four anchor dredge benthic stations in Wellington Harbour are then treated statistically, and compared to the visual assessments. It appears that the great variability in Wellington Harbour sediments makes identity of classical communities in the harbour almost impossible. However, station groups (groups of stations with similar bivalve species present) are evident, and their distribution in Wellington Harbour correlate closely to sediment type distribution. Lists of the most abundant bivalve species occurring in both harbours, deduced from all the observations presented in this study, are given. (3) Observations were made on the occurrence of common late stage bivalve larvae in the plankton at Bay of Islands and Wellington Harbour during 1979 - 71. Three stations in Bay of Islands and four stations in Wellington Harbour were sampled approximately monthly. The bivalve larvae in shorter series of plankton samples from Raumati Beach, Dargaville Beach, Mahurangi, Ohiwa Harbour, Raglan Harbour and Kaipara Harbour during 1971 - 72 were also analysed. Twenty-nine species of bivalve larvae from these plankton samples are described. Twenty-three species of late stage bivalve larvae are provisionally identified, the identifications being based on the larval hinge structure, the distribution and abundance of the larvae in relation to adult stocks, and in some cases by correlation with the adult gonad or condition index cycle. The broad seasonal pattern of occurrence of twenty five species of late stage bivalve larvae in the plankton at Bay of Islands, Wellington Harbour and Raumati Beach is presented. (4) Ecological studies made on bivalve larvae at Bay of Islands and Wellington Harbour during 1970 - 71, are presented and compared to other published studies from overseas. Included are observations on the vertical meso-distribution of bivalve larvae over tidal cycles in estuarine and non-estuarine localities of l2m to l5m depth, the daytime vertical meso-distribution of bivalve larvae in non-estuarine water 20m- 30m in depth, the effect of light on the vertical meso-distribution of bivalve larvae in water 15m- 30min depth, and the horizontal mega-distribution of bivalve larvae in Wellington Harbour and Bay of Islands. The observations suggest that in estuarine areas, the effect of alternating tides on the vertical distribution of bivalve larvae far outweighs the effects of any other factors. During the flood tide, bivalve larvae rise from the bottom into the water column and are carried up the estuary by the tide. During the ebb tide the larvae settle and remain on the bottom. In non-estuarine areas, no such vertical migration was observed. Gravity, light and water currents, in particular, affect the vertical distribution of bivalve larvae in these areas. The horizontal mega-distribution of bivalve larvae within Wellington Harbour is fairly uniform. In Bay of Islands, bivalve larvae occur in greatest densities near the shores, while much of the central basin is almost devoid of larvae. This distribution is due to the proximity of the adult stocks to the regions of most larvae, and to the prevailing water current pattern within the bay.</p>

Assessment of the Impact on Human Health of the Presence of Norovirus in Bivalve Molluscs: What Data Do We Miss?

In the latest One Health ECDC EFSA technical report, Norovirus in fish and fishery products have been listed as the agent/food pair causing the highest number of strong-evidence outbreaks in the EU in 2019. This review aims to identify data gaps that must be filled in order to increase knowledge on Norovirus in bivalve molluscs, perform a risk assessment and rank the key mitigation strategies for this biological hazard, which is relevant to public health. Virologic determinations are not included in any of the food safety and process hygiene microbiologic criteria reflected in the current European regulations. In addition, the Escherichia coli-based indices of acceptable faecal contamination for primary production, as well as the food safety criteria, do not appear sufficient to indicate the extent of Norovirus contamination. The qualitative risk assessment data collected in this review suggests that bivalve molluscs present a high risk to human health for Norovirus only when consumed raw or when insufficiently cooked. On the contrary, the risk can be considered negligible when they are cooked at a high temperature, while information is still scarce for non-thermal treatments.

TAXONOMIC COMPOSITION AND QUANTATIVE INDICATORS OF MACROZOOBENTHOS IN WATER BODIES OF WEST KAZAKHSTAN REGION

The article presents the results of the study of macrozoobenthos communities of six lakes in the West Kazakhstan region in the summer-autumn period: Shalkar, Balykty Sarkyl, Edilsor, Glubinnoye, Prorva and Sulukol. Lakes Prorva and Sulukol are located within the steppe, the lakes Shalkar, Balykty Sarkyl, Glubinnoye - in the semi-desert, Lake Edilsor - in the desert zone. In total, 197 samples of zoobenthos were taken according to generally accepted hydrobiological methods. There are analized the indices of the number and biomass of aquatic organisms in the studied reservoirs. According to the results of the studies carried out, the organisms of 66 taxa from the groups Oligochaeta, Hirudinea, Bivalvia, Gastropoda, Crustacea, and Insecta were found in benthic samples. Of thesethere were found oligochaetes - 2 species, leeches - 1 species, bivalves and gastropods - 3 species each, crustaceans - 4 species and insects - 53 taxa. Among insects, dip-terans (23 taxa, of which chironomids - 18), mayflies, caddis flies, dragonflies, bugs and beetles were distinguished by the greatest species diversity. It was noted that in the composition of benthic communities, diptera larvae dominated in abundance, the main contribution to the biomass was made by bivalve molluscs. Calculations of the Shannon – Weaver index demonstrate a low species diversity of communities for all water bodies. The highest indices of species diversity were noted in Lake Edilsor - 1.64 bit / specimen, the lowest - in lakes Sulukol and Shalkar - 0.6 bit / specimen. and 0.7 bit / copy. respectively. According to the calculations of the saprobity index, lakes Glubinnoye, Prorva and Balykty Sarkyl belong to the ß-mesosaprobic zone, Lake Edilsor (S = 2.72) to the ɑ-mesosaprobic zone, and the indicators of Lake Sulukol (S = 3.8) correspond to the polysaprobic zone. The values of the saprobity indices of the studied lakes lie within the beta-mesosaprobic – polysaprobic zones. By water quality the studied lakes are assessed as moderately polluted and polluted. According to the classification of S.P. Kitaev (2007) the investigated water bodies are assessed as water bodies of medium feeding. The conducted studies have significantly expanded the taxonomic lists of benthic organisms in this region

Bivalves (Mollusca: Bivalvia) in Malaysian Borneo: status and threats

Species checklists enlist the species existing within a distinct geographical biome and assist as an indispensable input for evolving conservation and administration strategies. The arenas of conservation ecology and biology face the challenge of exaggerated biodiversity, accredited to the non-recognition of taxonomic inconsistencies. The study’s goals are to organize all scattered taxonomic information regarding bivalve molluscs from Malaysian Borneo, i.e. Sarawak and Sabah, under one umbrella. Available literature regarding Malaysian Borneo was reviewed. The published taxonomic data on bivalve species, conservation status, inconsistencies, habitats (marine, fresh, and brackish), research aspects, threats, and conservation strategies are presented. A critical review of the checklists and distributional records of the class Bivalvia from Malaysian Borneo and subsequent validation of species names with the World Register of Marine Species (WoRMS) database revealed that currently 76 bivalve species from 12 orders and other entities, 18 superfamilies, and 27 families have been recorded from the area. Twenty-six inconsistencies with WoRMS were found, and the corrected names are presented. The study indicates most of the enlisted bivalve species have not been evaluated by the IUCN Red List authority and have ‘Least Concern’ or ‘Data Deficient’ status for Malaysian Borneo. To date, published documents on conservation decision strategies and guidelines for future research are not good enough. Nevertheless, potential threats and their remedies for bivalves in the enriched Malaysian Borneo ecosystems are discussed herein.