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Background: Short interspersed nuclear elements (SINEs) are non-autonomous non-LTR retrotransposons widespread across eukaryotes. They exist both as lineage-specific, fast-evolving elements and as ubiquitous superfamilies characterized by highly conserved domains (HCD). Several of these superfamilies have been described in bivalves, however their overall distribution and impact on host genome evolution are still unknown due to the extreme scarcity of transposon libraries for the clade. In this study, we examined more than 40 bivalve genomes to uncover the distribution of HCD-tRNA-related SINEs, discover novel SINE-LINE partnerships, and understand their possible role in shaping bivalve genome evolution. Results: We found that bivalve HCD SINEs have an ancient origin, and they can rely on at least four different LINE clades. According to a "mosaic" evolutionary scenario, multiple LINE partner can promote the amplification of the same HCD SINE superfamilies while homologues LINE-derived tails are present between different superfamilies. Multiple SINEs were found to be highly similar between phylogenetically related species but separated by extremely long evolutionary timescales, up to ~ 400 million years. Studying their genomic distribution in a subset of five species, we observed different patterns of SINE enrichment in various genomic compartments as well as differences in the tendency of SINEs to form tandem-like and palindromic structures also within intronic sequences. Despite these differences, we observed that SINEs, especially older ones, tend to accumulate preferentially within genes, or in their close proximity, consistently with a model of survival bias for less harmful, short non-coding transposons in euchromatic genomic regions. Conclusion: Here we conducted a wide characterization of tRNA-related SINEs in bivalves revealing their taxonomic distribution and LINE partnerships across the clade. Moreover, through the study of their genomic distribution in five species, we highlighted commonalities and differences with other previously studied eukaryotes, thus extending our understanding of SINE evolution across the tree of life. [ABSTRACT FROM AUTHOR]

A major expense in the operation of bivalve nurseries is the culture of high‐quality live microalgae feeds, and efforts to develop effective alternative feeds have had limited success. Juvenile bivalves are known to be able to absorb dissolved nutrients, but this ability has received minimal attention as a route for supplementary feeding. This study assessed the capacity of juvenile green‐lipped mussels (GLMs) (Perna canaliculus) to uptake and assimilate dissolved glucose at five experimental concentrations (i.e. 10 µg mL−1, 100 µg mL−1, 1 mg mL−1, 10 mg mL−1 and 30 mg mL−1) as a supplement to cultured microalgae. Growth and survival of the mussels were measured over 3 weeks. Although all glucose concentrations improved the performance of mussel spat compared to the control, the best performing was a concentration of 1 mg mL−1 of dissolved glucose which enhanced daily spat growth 2.7 times that of the control live microalgal diet without glucose. Survival was high (i.e. >95%) for all treatments except for the highest experimental concentration of glucose, for which a concentration of 30 mg mL−1 resulted in mean mortality of 24%. Mussel spat supplemented with dissolved glucose accumulated up to 30% greater lipid and improved the carbohydrate content per mg g−1 of ash‐free dry weight as much as 3.5 times compared to those in the control treatment, indicating that they were in greater nutritional condition. This demonstration that dissolved glucose can be used to fuel growth by GLM spat at concentrations as low as 10 µg mL−1 suggests that other soluble nutrients may also act as a supplemental feed for cultured juvenile molluscs. Dissolved nutrients have the potential to improve the performance of spat in nursery systems while simultaneously reducing the reliance of cultured microalgae as a sole feed input. [ABSTRACT FROM AUTHOR]

The global spread of non-native species is leading to an increasing frequency of multiple co-occurring non-native species. We examined the co-occurrence of the bivalve mollusc Dreissena polymorpha (zebra mussel) with three Ponto-Caspian amphipods (Dikerogammarus villosus, Dikerogammarus haemobaphes, and Chelicorophium curvispinum) across England and Wales in association with in-situ substrate size. For all three amphipod species, substrate grain size where amphipods co-occurred with D. polymorpha was significantly finer than when recorded in isolation. Subsequently, we confirmed this via aquarium experiments. We examined the occurrence of D. villosus with D. polymorpha when present with cobbles, gravel, or sand from three population sources (co-location with abundant D. polymorpha populations, co-location with low populations, and naïve). Experiments demonstrated that D. villosus actively sought shelter on or near D. polymorpha, with their co-location being significantly more prevalent in finer grained substrates (sand > gravel > cobble). The strength of this co-location differed by population source, with those co-located with high D. polymorpha densities demonstrating a greater association. Our analyses and experiments indicate that D. polymorpha may facilitate Ponto-Caspian amphipod establishment in otherwise suboptimal locations, whereby mussel shells provide favourable structural habitat for the amphipods, analogous to the presence of coarse-grained benthic sediment. [ABSTRACT FROM AUTHOR]

Mollusc shells are among the most abundant and well-preserved organisms in sediments worldwide, but their shells are usually subject to fragmentation due to exposure time in the TAZ, which compromises their preservation potential. The shell strength of valves from life and death assemblages from the sandy beaches of Santa Clara (37°50′49″S, 57°30′16″W) and Mar Chiquita (37°44′45″S, 57°25′1.5″W) on the Bonaerense coast, southwest Atlantic Argentina, was analysed to capture the effect of taphonomic processes over time and to determine how intrinsic properties and taphonomic variables influence their shell strength. To achieve this, the mechanical resistance profile of the bivalve Eucallista purpurata was assessed using point load and microindentation tests, and the mineralogical composition and organic matter content of the shell, as well as morphological variables, were measured. We concluded that, as expected, shells from life assemblages were more resistant to compression than those from death assemblages, but surprisingly, right valves were more resistant to compression than left valves in both Mar Chiquita and Santa Clara death assemblages. No differences were observed between broken and unbroken shells. [ABSTRACT FROM AUTHOR]

The freshwater mussels (Bivalvia: Unionida) of the biodiversity hotspot Sundaland are experiencing severe anthropogenic threats, whilst their diversity and distribution remain poorly understood. Here, we present the first modern-day data on Unionida diversity and distribution across western Borneo. Mussels were surveyed and collected in the upper Kapuas and Pawan river basins in West Kalimantan, Indonesia, and the Sambas Besar, Sarawak and Batang Sadong river basins in Sarawak, Malaysia. DNA sequencing (COI  + 16S +  ND1  + 18S + 28S) and morphological analyses were conducted to delineate and identify species, and reconstruct phylogenetic relationships and population genetics. Specimens belonged to six native genera and nine species, of which seven are endemic to Borneo and three are new to science, i.e. Ctenodesma mawonae Zieritz et al. sp. nov. Sarawak basin, and Ctenodesma bersinara Zieritz et al. sp. nov. and Rectidens lauris Zieritz et al. sp. nov. both Pawan basin. The monotypic genera Caudiculatus and Discomya were phylogenetically highly divergent from other known Gonideinae taxa, potentially indicating a separate tribe (for Caudiculatus) and subfamily (for Discomya). In addition, we report new records of the non-native Sinanodonta pacifica Heude, 1878 in the Batang Sadong and Kapuas river basins. [ABSTRACT FROM AUTHOR]

We describe a high‐diversity silicified assemblage of marine molluscs (Pelsa‐Vazzoler Lagerstätte) from the upper Ladinian of the Agordo Dolomites (northeastern Italy). New data on the Triassic rebound, after the end‐Permian mass extinction, constrain it to an interval of relatively stable climatic conditions. This Lagerstätte, in the Sciliar Formation, yields a structure comparable to the famous lower Carnian San Cassiano Lagerstätte and suggests that the radiation of benthic molluscs may have occurred as early as the late Middle Triassic. We classified more than 4800 Cassian‐type molluscs, measuring abundance distributions of 109 species, including one new family (Rhaetidiidae), three new genera (Pelsia, Gaetania, Agordozyga) and 21 new species: Grammatodon egortinus, Modiolus friesenbichlerae, Myoconcha busattae, Schizogonium letiziae, Predazzella? monarii, Eucycloscala nitida, Tricolnaticopsis elongatus, Cortinella stricta, Triadoskenea alpicornu, Trachynerita tenuicostata, Coelostylina civettae, Gaetania coronata, Agordozyga caprina, Euthystylus dincae, Zygopleura elongata, Diatrypesis agordina, Cryptaulax pelsae, Pseudoscalites karapunari, Promathildia gracile, Camponaxis ladinica and Striactaeonina ingens. In this fauna, associated with tropical carbonate platforms, epifaunal filter‐feeding bivalves adopted new antipredatory features and gastropods conquered new ecospace, including parasitism and microcarnivory on sponges and scleractinian corals. Small size was an advantage in an ecosystem of small, isolated patch reefs. This is how, where and when caenogastropod and heterobranch snails (groups that today dominate global marine diversity) began their rise in the marine benthos. The origins of some evolutionary innovations that are key to our understanding of the time and place of the Mesozoic Marine Revolution, are therefore pushed back to the Middle Triassic. [ABSTRACT FROM AUTHOR]

The microbiological monitoring of bivalve mollusk harvesting areas in the Marche region is based on the parameters of Escherichia coli and Salmonella spp. However, Regulation EU/2019/627 stated criteria based on E. coli only to determine the health status of these areas. Therefore, the reason for Salmonella spp. monitoring, as provided in the Marche region, could be aimed at reducing the risk of placing on the market contaminated bivalve mollusks. This study, using the results of microbiological monitoring carried out in the Marche region from 2015 to 2022 and the methods based on Bayes' theorem and Poisson's distribution, evaluated the effectiveness and efficiency of Salmonella spp. monitoring in reducing the risk to the consumer. The results show that i) the use of a single sample unit significantly reduced the possibility of detecting non-compliance with the microbiological safety criterion; ii) the time taken to report positive results (average of approximately 10 days) did not allow the timely implementation of control measures; iii) the prevalence of positive outcomes was quite sporadic: a random trend of positivity is recognizable on a geographical and monthly basis for mussels and a geographical basis for striped clams; iv) considering the predictive value of E. coli against Salmonella spp., the specificity is very high and the negative predictive value versus Salmonella spp. would be >80%. In conclusion, the study shows that the monitoring of Salmonella spp. has a limited effect on reducing the risk to the consumer; however, in the cost/benefit assessment, other aspects not covered by this study should be considered. [ABSTRACT FROM AUTHOR]

This article presents data on lithology, biostratigraphy, and molluscan paleontological characteristics of the Lower Volgian–Upper Ryazanian interval of the Yanov Stan Formation obtained from the core of the Novoyakimovskaya-1 parametric well. The formation consists of mudstone-siltstone intercalation with rare sandstone beds and numerous levels with carbonate concretions. For the first time, abundant glendonites are reported from the Yanov Stan Formation, including stratigraphic intervals from which they have not been previously known. An almost complete 290-m core of the Yanov Stan Formation with abundant ammonites and bivalves was obtained. This enabled us to develop a detailed biostratigraphic zonation of the section based on ammonites and bivalves. The following succession of ammonite zones, known in Western Siberia and, mainly, in Eastern Siberia (from bottom to top), was established: Paravirgatites lideri, Pavlovia iatriensis, Dorsoplanites ilovaiskii, D. maximus, Epivirgatites variabilis, Praechetates exoticus, Craspedites okensis, Praetollia maynci, Hectoroceras kochi, and Surites subanalogus. The bivalve succession, distinguished based on the members of the genus Buchia, includes the following Buchiazones: Buchia mosquensis, B. unschensis, B. okensis, ?B. jasikovi, and B. volgensis. The molluscan assemblages of the studied core, starting at least from the upper Middle Volgian, are similar to the coeval assemblages from the eastern part of the Yenisei–Khatanga depression and the Laptev Sea coast but differ from those from Western Siberia. This suggests the existence of some environmental factors that prevented the free distribution of mollusks from the western part of the Yenisei–Khatanga depression into the West Siberian basin. [ABSTRACT FROM AUTHOR]

North America is home to some of the most diverse freshwater mussel fauna (Mollusca: Unionidae) in the world, with the majority of mussel diversity located in the southeastern United States. Unfortunately, mussels are one of most imperiled groups in the world and species are declining across the United States. Anthropogenic habitats may function as refugia for some mussel species; however, many of these habitats are ignored during studies. The False River of Louisiana is a unique system that has separated from the Mississippi River and is dependent on an artificial canal system to maintain water levels. The canal may act as refugia for mussels during climatic events, but it is unknown whether the system can sustain mussels. To obtain an understanding of the structure and health of mussels within this anthropogenic structure, we surveyed mussels and fish at 11 sites in a section of artificial canal connected to the False River. We analyzed the mussel assemblage with regard to life history strategies and compared fish presence to known fish host use of our various mussel species. We collected 388 individuals of 13 live mussel species, with 5 additional species located as shell material. The fish assemblage consisted of 22 species of which 15 were hosts for at least one member of the mussel assemblage. The mussel assemblage primarily consisted of opportunistic species and host generalists with a few dominant species. This is, to our knowledge, the first mussel peer-reviewed mussel data reported from any portion of the False River system and the mussel assemblage appears to follow predictable trends for flashy systems noted in other rivers. Our study highlights that the False River canal system is capable of sustaining mussels and indicates that anthropogenic structures should be incorporated into future survey efforts. [ABSTRACT FROM AUTHOR]

The population dynamics of Polititapes aureus from Tunisia were investigated monthly during a one-year period (2018). The possible future commercial benefits of the species as a significant resource of artisanal fisheries require better knowledge of its population dynamics. This study provides the first insight into population parameters by investigating its population structure, growth, mortality, and exploitation rate. Allometric relationships between body size and length were determined. The shell length/ total weight ratio indicated a positive allometric growth and was expressed as TW = 0.0002 SL3.103. Length frequency data were analyzed to estimate population parameters using FiSAT ΙΙ software. P. aureus showed lower growth rate (K = 0.46 yr–1) and asymptotic length (L∞ = 38.80) compared to those obtained for other bivalve species (mean values: K = 0.61 and L∞ = 55.02). Longevity (Tmax) and the growth performance index (φ') were 7.95 yr-1 and 2.84, respectively. Total mortality (Z) was estimated from the length-converted catch curve at 0.85 yr-1 and fishing mortality (F) at 0.03 yr-1. Both values of natural mortality (M = 0.82 yr-1) derived from bivalve literature and based on Pauly's (1980) empirical equation (M = 0.83 yr-1) developed for fish were comparable. The most intensive growth occurred during the first three years. The data presented herein are crucial for appropriate fisheries management and conservation of clams. [ABSTRACT FROM AUTHOR]

The bivalve mollusc Pinna nobilis, endemic to the Mediterranean Sea, has been vanishing since 2016 from the whole basin because of an infection by multiple pathogens that caused mass mortality events. In the Eastern Mediterranean, some small populations seem to be resistant to the infection. These individuals could represent the only possibility for the species to recolonize desert habitats. Thus, according to the recommendations of IUCN, looking for living specimens of P. nobilis is a priority. With this goal in mind, we carried out surveys in different areas of Southern Italy, and in 2018, we launched a Citizen Science campaign to involve recreational and professional divers in this challenge. As a result of a monitoring activity carried out in 2022–2024, along the Ionian coast of Apulia, in Southern Italy, we can say that there are no more living specimens there but only empty shells. Concurrent to the vanishing of the queen P. nobilis, its congeneric P. rudis, resistant to the infection, seems to be taking advantage, becoming more common and colonizing habitats once exclusive to P. nobilis. In fact, from different areas of the Mediterranean, sightings of the new possible queen, P. rudis, are increasing, together with the discovery of individuals exhibiting morphological traits that are a mixture of the two species. In some cases, these morphological features are not easy to detect; nevertheless, the presence of these hybrids, resistant to the infection, is important for the conservation of the species. [ABSTRACT FROM AUTHOR]

A total of 11 orders, 22 families, 45 genera and 48 species of mussels are known from the Bulgarian aquatory of the Black Sea. They are divided into 23 zoogeographical categories. The predominant part of them are Atlantic-Mediterranean elements (30 species or 62.5%). In the Bulgarian shelf there are from eight to 12 biocenoses and a large number of groups, which are characterised by specific types of mussels. The belts of Mytilus galloprovincialis and Modiolula phaseolina are typical of the Black Sea. Biogenic reefs built by Ostrea edulis but without living forms have been established. Four alien species are recorded, of which two are invasive. Nineteen species (39.6%) have a conservation value. [ABSTRACT FROM AUTHOR]

The research included 120 specimens of Pinna nobilis cultivated at a commercial park for oyster (Ostrea edulis) and black mussel (Mytilus galloprovincialis) cultivation. Research was carried out from 2012 to 2016, prior to the start of the mass extinction of fan mussel in the Mediterranean During the study period, the average sea temperature at a depth of 3 m was 14.87 ± 4.22 °C, ranging from 7.83 to 24.90 °C. The age of the specimens at the beginning of sexual maturity was approximately three years. The average length of the specimens throughout the study was 293.01 ± 16.58 mm. Gonad status was monitored monthly by sampling. The gender ratio in the study was 46 females (38.4%), 50 males (41.6%), and 24 undetermined individuals (20%). In our study, the results showed that males mature slightly earlier than females. The main spawning season occurred during the warmer part of the year when seawater exceeded 18 °C, starting in May and lasting until November. During the study, the GSI varied as expected and peaked in June (12.1), increasing from May to September. [ABSTRACT FROM AUTHOR]

We report new data on non-indigenous invertebrates from the Mediterranean Sea (four ostracods and 20 molluscs), including five new records for the basin: the ostracods Neomonoceratina iniqua, Neomonoceratina aff. mediterranea, Neomonoceratina cf. entomon, Loxoconcha cf. gisellae (Arthropoda: Crustacea)–the first records of non-indigenous ostracods in the Mediterranean–and the bivalve Striarca aff. symmetrica (Mollusca). Additionally, we report for the first time Electroma vexillum from Israel, and Euthymella colzumensis, Joculator problematicus, Hemiliostraca clandestina, Pyrgulina nana, Pyrgulina microtuber, Turbonilla cangeyrani, Musculus aff. viridulus and Isognomon bicolor from Cyprus. We also report the second record of Fossarus sp. and of Cerithiopsis sp. cf. pulvis in the Mediterranean Sea, the first live collected specimens of Oscilla galilae from Cyprus and the northernmost record of Gari pallida in Israel (and the Mediterranean). Moreover, we report the earliest records of Rugalucina angela, Ervilia scaliola and Alveinus miliaceus in the Mediterranean Sea, backdating their first occurrence in the basin by 3, 5 and 7 years, respectively. We provide new data on the presence of Spondylus nicobaricus and Nudiscintilla aff. glabra in Israel. Finally, yet importantly, we use both morphological and molecular approaches to revise the systematics of the non-indigenous genus Isognomon in the Mediterranean Sea, showing that two species currently co-occur in the basin: the Caribbean I. bicolor, distributed in the central and eastern Mediterranean, and the Indo-Pacific I. aff. legumen, at present reported only from the eastern Mediterranean and whose identity requires a more in-depth taxonomic study. Our work shows the need of taxonomic expertise and investigation, the necessity to avoid the unfounded sense of confidence given by names in closed nomenclature when the NIS belong to taxa that have not enjoyed ample taxonomic work, and the necessity to continue collecting samples–rather than relying on visual censuses and bio-blitzes–to enable accurate detection of non-indigenous species. [ABSTRACT FROM AUTHOR]

Crassostrea gasar is a bivalve mollusk of economic interest in the Amazon estuary, because it displays good zootechnical performance and nutritional value. However, there is still a gap in the literature regarding studies on basic biology, especially spermatogenesis at the ultrastructural level. This study aimed to describe for the first time the male gonad development. Gonad fragments were analyzed using light microscopy and transmission and scanning electron microscopy. The ultrastructural analysis of the gonadal tubule showed two distinct cell populations: support cells and the cells of the spermatogenic lineage. Regarding the ultrastructural aspects, support cells were characterized by an irregular shape, sparse electron-dense cytoplasm, and a large nucleus with condensed chromatin; and two types of spermatogonia were seen (A and B); spermatocytes I where it was possible to characterize four stages of prophase I, namely leptotene, zygotene, pachytene, diplotene; spermatocytes II showing a reduction in cytoplasmic and condensed chromatin. Spermatids were classified into three stages of development: early, middle, and late. Mature spermatozoa are of the primitive type and have a cone-shaped head with a discoidal acrosome, a midpiece formed by four mitochondria, and a long flagellum. This information can help establish phylogenetic relationships between species of the genus Crassostrea. In addition, these findings can support conservation biology by developing and implementing biotechnological approaches, such as cryopreservation, and contributing to commercial-scale cultivation in the Amazon region. [ABSTRACT FROM AUTHOR]

In estuarine food webs, bivalve molluscs transfer nutrients and pollutants to higher trophic levels. Mercury (Hg) pollution is ubiquitous, but it is especially elevated in estuaries historically impacted by industrial activities, such as those in the U.S. Northeast. Monomethylmercury (MeHg), the organic form of Hg, is highly bioaccumulative and transferable in the food web resulting in the highest concentrations in the largest and oldest marine predators. Patterns of Hg concentrations in marine bivalve molluscs, however, are poorly understood. In this study, inorganic Hg (iHg), MeHg, and the total Hg (THg) in soft tissues of the northern quahogs (Mercenaria mercenaria), eastern oysters (Crassostrea virginica), and ribbed mussels (Geukensia demissa) from eastern Long Island sound, a temperate estuary of the western North Atlantic Ocean was investigated. In all three species, concentrations of THg remained similar between the four sampling months (May, June, July, and September), and were mostly independent of animal size. In quahogs, MeHg and iHg displayed significant (p < 0.05) positive (iHg in May and June) and negative (MeHg in July and September) changes with shell height. Variability in concentrations of THg, MeHg, and iHg, both inter- and intra-specifically was high and greater in quahogs and oysters (THg: 37, 39%, MeHg: 28, 39%, respectively) than in mussels (THg: 13%, MeHg: 20%). The percentage of THg that was MeHg (%MeHg) was also highly variable in the three species (range: 10–80%), highlighting the importance of measuring MeHg and not only THg in molluscs. [ABSTRACT FROM AUTHOR]

Simple Summary: The genetic pool of invasive species greatly influences their ability to establish and spread. The blue mussels Mytilus galloprovincialis, originating from the Mediterranean, are major invaders worldwide. Our study examined their genetic diversity and structure in Chile, comparing them with native populations. We used mitochondrial DNA to analyze the genetic traits and origins of invasive populations. Two lineages of M. galloprovincialis were identified, i.e., NW Atlantic and Mediterranean. Although recently introduced, no genetic structure was found in Chilean populations. However, a mixture of lineages increased the genetic diversity along the coast. The invasion coastal extent remains small (~100 km), suggesting their recent introduction. The expansion of these populations may encounter natural barriers; nevertheless, it is advisable to monitor these species' distribution. The genetic characteristics of invasive species have a significant impact on their ability to establish and spread. The blue mussel (Mytilus galloprovincialis), native to the Mediterranean Sea, is a leading invasive species of intertidal coasts throughout much of the world. Here, we used mitochondrial DNA sequence data to investigate the genetic diversity and phylogeographic structure of invasive (M. galloprovincialis) versus native (Mytilus chilensis) populations of blue mussels in Chile. We evaluated whether genetic diversity in invasive populations could be explained by the genetic characteristics of the native sources from which they might be derived. A phylogenetic analysis confirmed two lineages of the invasive M. galloprovincialis, i.e., the NW Atlantic and the Mediterranean lineages. We found no evidence of genetic structure in the invasive range of M. galloprovincialis in Chile, most probably because of its recent arrival. We did, however, detect a spatial mixture of both M. galloprovincialis lineages at sampling locations along the Chilean coast, giving rise to higher levels of genetic diversity in some areas compared to the population of native M. chilensis. The coastal area of the invasion is still small in extent (~100 km on either side of two large ports), which supports the hypothesis of a recent introduction. Further expansion of the distribution range of M. galloprovincialis may be limited to the north by increasing water temperatures and to the south by a natural biogeographic break that may slow or perhaps stop its spread. The use of internal borders as a tool to minimise or prevent M. galloprovincialis spread is therefore a genuine management option in Chile but needs to be implemented rapidly. [ABSTRACT FROM AUTHOR]

Cyrtopleura costata is a pholadid bivalve that inhabits tidal flats inside burrows c. 40 cm deep, and its visceral mass outgrows its shell significantly. Thus, unlike other bivalves, it cannot isolate its soft tissues from the external environment through complete valve closure. One can thus hypothesize that this bivalve would be inevitably more exposed and susceptible to the tidal changes in salinity. No information regarding its osmoregulatory physiology has been found in the literature. We thus investigated how its fluids would respond to seawater dilution and seawater concentration, and how its tissues would be able to keep their moisture content. Individuals of C. costata were acclimated to 30‰ and then independently exposed stepwise (1 h for each 5‰ change) to 25, 20, 15 and 10‰ or to 35, 40, 45 and 50‰. Isolated tissue slices obtained from control animals (30‰) of siphon, mantle and muscle were exposed in vitro to salines corresponding to salinities of 10, 30 and 50‰. Cyrtopleura costata responded as a typical euryhaline osmoconformer between 25 and 40‰, with haemolymph and mantle cavity water being isosmotic to the external medium. However, some 'buffering' of haemolymph osmolality was displayed in the most extreme salinities, 10–20‰ and 45–50‰. This could result from muscle contraction and other cellular responses, reducing 'apparent permeability' and diffusive fluxes; the muscle was the tissue with the highest capacity to maintain constant hydration despite significant osmotic challenge. Both in vivo and in vitro experiments indicated a higher tolerance of salinity increases than decreases. Thus, if global and local changes in climate and precipitation rates result in more frequent seawater dilution in its habitat, the area occupied by its realized niche may be reduced. [ABSTRACT FROM AUTHOR]

This study investigated the prevalence and genetic diversity of gastroenteric viruses in mussels and oysters in Rio de Janeiro, Brazil. One hundred and thirty-four marketed bivalve samples were obtained between January and December 2022. The viral analysis was performed according to ISO/TS 15216, and the screening revealed the detection of norovirus GII/GI (40.3%), sapovirus (SaV; 12.7%), human mastadenovirus (7.5%), and rotavirus A (RVA; 5.9%). In total, 44.8% (60) of shellfish samples tested positive for one or more viruses, 46.7% (28/60) of the positive samples tested positive for a single viral agent, 26.7% (16) tested positive for two viral agents, 8.3% (5) for three viral agents, and 13.3% (8) for four viral agents. Additionally, three mussel samples were contaminated with the five investigated viruses (5%, 3/60). Norovirus GII showed the highest mean viral load (3.4 × 105 GC/g), followed by SaV (1.4 × 104 GC/g), RVA (1.1 × 104 GC/g), human mastadenovirus (3.9 × 103 GC/g), and norovirus GI (6.7 × 102 GC/g). Molecular characterization revealed that the recovered norovirus strains belonged to genotypes GII.2, GII.6, GII.9, GII.17, and GII.27; SaV belonged to genotypes GI.1 and GIV.1; RVA to genotypes G6, G8, P[8]-III, and human mastadenovirus to types F40 and F41. The GII.27 norovirus characterized in this study is the only strain of this genotype reported in Brazil. This study highlights the dissemination and diversity of gastroenteric viruses present in commercialized bivalves in a touristic area, indicating the potential risk to human health and the contribution of bivalves in the propagation of emerging pathogens. [ABSTRACT FROM AUTHOR]

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This work focused on assessing of the risk associated with the consumption of bivalve mollusks, potentially contaminated with phycotoxins. The studied phycotoxins are saxitoxin (STX), okadaic acid (OA), dinophysistoxins (DTXs), yessotoxins (YTXs), pectenotoxins (PTX), azaspiracids (AZAs), and domoic acid (DA). These toxins were investigated in three species of bivalve mollusks (Anadara senilis, Crassostrea gasar, and Perna perna), originating from the Ebrié lagoon. Chemical analyses were carried out by LC-MS/MS, HPLC-FLD, and HPLC-UV. The level of OA and DTXs, STX, and DA was 10.92 µg OA eq./kg, 9.6 µg STX eq./kg, and 0.17 mg DA eq./kg, respectively. The level of PTXs and AZAs was 3.3 µg PTX-2 eq./kg and 13.86 µg AZA-1 eq./kg; that of YTXs was 0.01 mg YTX eq./kg. The daily exposure dose (DED) was 0.019 µg OA eq./kg bw for OA and DTXs; 0.285 µg DA eq./kg bw for DA; 0.006 µg PTX-2 eq./kg bw for PTXs; 0.016 µg STX eq./kg bw for STX; 0.01 µg YTX eq./kg bw for YTXs; and 0.024 µg AZA-1 eq./kg bw for AZAs for the oyster Crassostrea gasar. These estimated values are lower than the acute reference dose (ARfD) of each phycotoxin recommended by the European Food Safety Agency (EFSA). The risk of harmful effects is acceptable. The absence of risk is valid only for the study period (11 months) and concerns coastal populations living near the sampling points. [ABSTRACT FROM AUTHOR]

Being the phylum with the second largest biodiversity, mollusks are widely distributed in marine, freshwater, and land, conquered almost all habitats on the earth. Throughout geological time, several molluscan lineages independently colonized freshwater and land, evolving independently in new habitats. Resolving the timing of their colonization for novel environments is the basis of understanding the complex evolution of Mollusca. Herein, we obtained an elaborate single-copy orthologs set including 107 genes with a total length of 3,447,675 amino acid sites across 134 mollusks to reconstruct the phylogeny of Mollusca. The phylogenetic analysis recovered the "Aculifera+ Conchifera" topology with well-supported. By the divergence times estimation with fossil calibration, we revealed Cambrian rapid diversification of all molluscan classes. What's more, our results provided the times of three major independent colonization of novel environments and consistent with previous studies. The freshwater mussels (Bivalvia: Unionida) colonized freshwater about 233 Mya, ancient origin and late diversification make this order to become the main represent of the freshwater bivalves. The orders Stylommatophora and Basommatophora (Gastropoda: Pulmonata) respectively colonized land and freshwater about 201 Mya, the Triassic-Jurassic mass extinction may have provided the opportunities for their colonization. Ampullariidae (Gastropoda) colonized freshwater about 156 Mya, their lungs may have contributed to the adaption of tropical freshwater environment and make them survive. Our results probably offer the most comprehensive time-scale of molluscan evolution, could provide some insights into the habitat transition and evolution of Mollusca. [ABSTRACT FROM AUTHOR]

Stable isotope sclerochemistry of mollusks and otoliths is frequently used for the reconstruction of paleotemperature and seasonality. Constraints on the paleoecology and –environment of these organisms, and how these factors influence intra-and inter-taxon isotope variability and variation, are thus highly valuable. We measured seasonal changes in δ18O and δ13C compositions in multiple specimens of two carditid bivalve species, a turritelline gastropod species, and two species of otoliths from demersal fish, from two early Eocene (latest Ypresian, 49.2 Ma) coquinas in the inner neritic Aalter Sand Formation, located in the Belgian part of the southern North Sea Basin (paleolatitude ~41° N). Results demonstrate variability among taxa in average, amplitude and shape of intra-annual δ18O and δ13C values. This intertaxon variability is at least partly caused by growth cessation during winters in turritellines and otoliths, leading to an incomplete representation of the seasonal cycle in their growth increments, compared to carditid bivalves. Other contributing factors to isotopic variability include sedimentary transport, mobility, and the lifespan of the specimens. Specifically, ophidiid fish otolith isotope records appear to reflect environmental conditions over a wider range of habitats and environments, due to sedimentary transport and postmortem transport by free-swimming predatory fish. Our study therefore highlights the variability between different taxa and environments in the shallow marine realm, which has implications for seasonality reconstructions. We show that by studying multiple taxa and specimens in a death assemblage, a more complete spectrum of isotope variation and variability becomes apparent. [ABSTRACT FROM AUTHOR]

A model organism in developmental biology is defined by its experimental amenability and by resources created for the model system by the scientific community. For the most powerful invertebrate models, the combination of both has already yielded a thorough understanding of developmental processes. However, the number of developmental model systems is still limited, and their phylogenetic distribution heavily biased. Members of one of the largest animal lineages, the Spiralia, for example, have long been neglected. In order to remedy this shortcoming, we have produced a detailed developmental transcriptome for the bivalve mollusk Mytilus galloprovincialis, and have expanded the list of experimental protocols available for this species. Our high-quality transcriptome allowed us to identify transcriptomic signatures of developmental progression and to perform a first comparison with another bivalve mollusk: the Pacific oyster Crassostrea gigas. To allow co-labelling studies, we optimized and combined protocols for immunohistochemistry and hybridization chain reaction to create high-resolution co-expression maps of developmental genes. The resources and protocols described here represent an enormous boost for the establishment of Mytilus galloprovincialis as an alternative model system in developmental biology. [ABSTRACT FROM AUTHOR]

Simple Summary: Microplastics (MPs) are anthropogenic microscopic pieces of plastic in marine sediments and the water column that can originate from two different sources. Primary MPs are industrially produced microbeads, while secondary MPs result from the fragmentation of larger plastic debris by physical, chemical, and biological processes. Although not yet considered a food contaminant, they are readily ingested by marine organisms at several trophic levels, thus entering the food chain and representing a risk to consumers of fishery products. In this study, Donax trunculus (Truncate donax) specimens collected from Class A production areas in the Tyrrhenian Sea (Mediterranean Sea), and therefore destined directly for the final consumer, were analyzed for the presence of MPs. First, all items were morphologically classified and measured, and some of these were chemically identified. Then, the MPs' mean abundance (MA) was calculated, and a risk assessment of human exposure to MPs was carried out. Both the MA of MPs and human exposure to MPs were found to be low. However, given the magnitude of the problem, the collection of further data using standardized methods is essential for a better risk assessment. Microplastics (MPs) (0.1 µm–5 mm particles) have been documented in oceans and seas. Bivalve molluscs (BMs) can accumulate MPs and transfer to humans through the food chain. BMs (especially mussels) are used to assess MPs' contamination, but the genus Donax has not been thoroughly investigated. The aim of this study was to detect and characterize MPs in D. trunculus specimens collected along the Tuscan coast (Italy), and to assess the potential risk for consumers. The samples (~10 g of tissue and intervalval liquid from 35 specimens) were digested using a solution of 10% KOH, subjected to NaCl density separation, and filtered through 5 μm pore-size filters. All items were morphologically classified and measured, and their mean abundance (MA) was calculated. Furthermore, 20% of them were analyzed by Raman spectroscopy and, based on the obtained results, the MA was recalculated (corrected MA) and the annual human exposure was estimated. In the 39 samples analyzed, 85 items fibers (n = 45; 52.94%) and fragments (n = 40; 47.06%) were found. The MA was 0.23 ± 0.17 items/grww. Additionally, 83.33% of the items were confirmed as MPs (polyethylene and polyethylene terephthalate). Based on the correct MA (0.18 MPs/grww), D. trunculus consumers could be exposed to 19.2 MPs/per capita/year. The health risk level of MPs was classified as level III (moderate). [ABSTRACT FROM AUTHOR]

Bivalves can concentrate biological and chemical pollutants, causing foodborne outbreaks whose occurrence is increasing, due to climatic and anthropic factors that are difficult to reverse, hence the need for improved surveillance. This study aimed to evaluate the hygienic qualities of bivalves sampled along the production and distribution chain in Sicily and collect useful data for consumer safety. Bacteriological and molecular analyses were performed on 254 samples of bivalves for the detection of enteropathogenic Vibrio, Arcobacter spp., Aeromonas spp., Salmonella spp., and beta-glucuronidase-positive Escherichia coli. A total of 96 out of 254 samples, collected in the production areas, were processed for algal biotoxins and heavy metals detection. Bacterial and algal contaminations were also assessed for 21 samples of water from aquaculture implants. Vibrio spp., Arcobacter spp., Aeromonas hydrophila, Salmonella spp., and Escherichia coli were detected in 106/254, 79/254, 12/254, 16/254, and 95/254 molluscs, respectively. A total of 10/96 bivalves tested positive for algal biotoxins, and metals were under the legal limit. V. alginolyticus, A. butzleri, and E. coli were detected in 5, 3, and 3 water samples, respectively. Alexandrium minutum, Dinophysis acuminata, Lingulodinium polyedra, and Pseudonitzschia spp. were detected in water samples collected with the biotoxin-containing molluscs. Traces of yessotoxins were detected in molluscs from water samples containing the corresponding producing algae. Despite the strict regulation by the European Commission over shellfish supply chain monitoring, our analyses highlighted the need for efficiency improvement. [ABSTRACT FROM AUTHOR]

In the Mediterranean Sea, the bivalve genus Pinna is represented by two species: the endemic Pinna nobilis and the (sub)tropical Atlantic Pinna rudis. P. rudis is generally less common and mostly restricted to the warmer regions of the western Mediterranean. However, since a mass mortality event, caused by a pathogen infection, has brought P. nobilis to the brink of extinction, records of P. rudis have increased in several Mediterranean regions, where it had not been previously observed. This paper reports on the presence of several P. rudis individuals in the Ligurian Sea, the northernmost reach of this species in the western Mediterranean. P. rudis has become increasingly common between 2021 and 2023, with a total of 28 new records from seven localities along the Ligurian coast. The size of the individuals and their estimated growth rate (3.6 cm·a−1) indicated that a recruitment event most likely took place in summer 2020, when P. nobilis was no longer present in the area. Our observations suggest that the recruitment success of P. rudis increased following the decline of P. nobilis. However, considering the thermophilic nature of P. rudis, in all likelihood, the ongoing water warming is playing a crucial role in the successful establishment of this species in the Ligurian Sea. A full understanding of the recent range expansion of P. rudis in the Mediterranean is far from being achieved, and whether P. rudis will be able to fulfil the ecological role of P. nobilis is difficult to predict. Large scale monitoring remains the only effective way to know about the future of Pinnids in the Mediterranean Sea. [ABSTRACT FROM AUTHOR]

Climate (in)stability can manifest in the size of mollusks attesting to variable impacts on growth, seasonal exploitation, and cultural persistence. We present population statistics of the height of a bivalve species (Donax obesulus) collected from sites dating to the Early Horizon (EH, 900–200 BCE) in the Nepeña Valley and the Middle Horizon (MH, 600–1000 CE) in the Jequetepeque Valley of northern coastal Peru and compare them with a paleoclimate record and a sample of modern shells (collected in 2012, 2014, and 2016) from the Nepeña Valley. We observe diachronic variation in the size of D. obesulus with larger bivalves during the EH and smaller shells during the MH and in the modern sample. D. obesulus size remains relatively static during the MH at one site through two sub-phases. These bivalve populations were likely impacted by both climate and cultural circumstances. A proxy for runoff from El Niño related rainfall (%lithic flux) from a previously published nearby marine sediment core is elevated during the EH and Late Moche phase of the MH and correlates with shell height. During the Transitional phase of the MH and the modern interval, however, there are periods of comparatively reduced El Niño activity and shell height compared to the EH. [ABSTRACT FROM AUTHOR]

Diverse, abundant and well-preserved mollusk fauna are here reported for the first time from the eastern coast Makram area, where Upper Miocene (Tortonian) sediments of the Dar Pahn Unit crop out, representing shoreface tidal influenced deposits composed mainly of ligh-gray marls. Multiple articulated bivalves and completely preserved the gastropod and bivalve shells indicate little or no transport at all from the original habitat of the mollusk assemblage. A total of 313 specimens, from which 271 correspond to gastropods, were identified only at generic level, since the purpose of this contribution is to offer an introduction to this exceptionally well-preserved mollusk assemblage. Previous studies of the area include detailed nannoplankton biostratigraphy and the report of a balaenopterid cetacean. Future studies include the detailed identification of the specimens, along with sediment analysis in order to find protoconchs and offer an extended version of this introductory report. [ABSTRACT FROM AUTHOR]

Given the limited understanding of benthic fauna along the Algerian coast, this study was conducted to explore the diversity of bivalve mollusks specifically on the Algerian west coast. The primary objectives of this study were to create a comprehensive but not exhaustive inventory of bivalve species in this region and to analyze the distribution of these species within the study areas and neighboring regions. The research involved the investigation of numerous sandy beaches across four sectors of the Algerian west coast: Tlemcen, Béni-Saf, Ain-Temouchent, and Oran. Between June 2019 and April 2020, a random collection of empty bivalve shells was carried out in the foreshore zones of 16 beaches within these sectors. This extensive collection of 10,076 shells resulted in the identification of 56 bivalve mollusk species, categorized into 22 families. Among these families, the most prominent were Cardiidae, Donacidae, Glycymerididae, and Veneridae, serving as the most representative families across all four sectors. Notably, the Glycymerididae family was the most abundant along the Oran coast, with nearly 2,000 individuals, although they were less prevalent on the beaches of the Béni Saf sector. In contrast, the Veneridae family was prevalent on the beaches of the Tlemcen, Béni Saf, and Aïn-Témouchent sectors. Within the Veneridae family, there was remarkable diversity, featuring 11 species, followed by the Cardiidae family with 6 species, and the Limidae and Pectinidae families with 5 species each. Finally, among the identified species, the most abundant ones included Acanthocardia tuberculata (Linnaeus, 1758), Chamelea gallina (Linnaeus, 1758), Glycymeris nummaria (Linnaeus, 1758), and Donax trunculus (Linnaeus, 1758), each belonging to the Cardiidae, Veneridae, Glycymerididae, and Donacidae families, respectively. [ABSTRACT FROM AUTHOR]

This paper presents the first comprehensive checklist of the non-marine molluscs from the western Himalaya, a region of high biodiversity and endemism. Based on faunistic surveys during 2019-2023 and published records, the paper reports 242 species belonging to 101 genera and 45 families of gastropods and bivalves, of which 168 species are endemic to the region. The paper also provides new distribution records and taxonomic notes for some species. Among the notable findings are the first records of Limax mayae, Oxyloma sp., Odhneripisidium kuiperi, Thiara aspera from India, and Bensonies jamuensis, Euaustenia cassida, Stagnicola sp. from the western Himalaya. The paper presents some species with substitutional illustrations and literature from the region for the past two centuries. Additionally, the paper also discusses the threats that non-marine molluscs face in the western Himalaya and suggests some conservation measures to protect them. The authors hope this paper will serve as a baseline for future studies on the diversity, distribution, ecology, and conservation of non-marine molluscs in the western Himalaya. [ABSTRACT FROM AUTHOR]

This comprehensive review presents a comparative analysis of early embryogenesis in Protostomia and Deuterostomia, the first of which exhibit a mosaic pattern of development, where cells are fated deterministically, while Deuterostomia display a regulatory pattern of development, where the fate of cells is indeterminate. Despite these fundamental differences, there are common transcriptional mechanisms that underline their evolutionary linkages, particularly in the field of functional genomics. By elucidating both conserved and unique regulatory strategies, this review provides essential insights into the comparative embryology and developmental dynamics of these groups. The objective of this review is to clarify the shared and distinctive characteristics of transcriptional regulatory mechanisms. This will contribute to the extensive areas of functional genomics, evolutionary biology and developmental biology, and possibly lay the foundation for future research and discussion on this seminal topic. [ABSTRACT FROM AUTHOR]

Bivalves (Mollusca: Bivalvia) and gastropods (Mollusca: Gastropoda) are a common component of diets in the Pacific Islands region. After consuming the soft tissue of these organisms, their shells are commonly discarded. We consider how such discards, or shell wastes, might serve as a resource for value-adding activities and focus on a case study of shell wastes being utilized for shellcraft in the Tigak Islands of Papua New Guinea. Through an interview-based approach, we investigate the composition and quantities of shell wastes generated by households, the extent these shell wastes are already integrated with shellcraft, and whether continued generation of these shell wastes remains possible. We found consumption of bivalves and gastropods varies among households, in both composition and quantities, such that each household generates unique shell wastes. However, shell wastes are seldom utilized for shellcraft, with substantial variation between the species consumed and the extent their shell wastes are utilized within households (F = 16.2, P < 0.01). For roughly half (n = 15) of all species consumed (n = 31), significant quantities of unutilized shell wastes coincided with positive perceptions of stock status. We argue that integrating shell wastes with shellcraft is a viable pathway to support livelihood enhancement. Our findings in this local context have regional significance in providing useful insights for guiding interventions to assist households better integrate shell wastes with shellcraft. [ABSTRACT FROM AUTHOR]

The elucidation of life-cycles of digeneans, with their successive larval stages, is facilitated by the use of molecular markers. Samples of sporocysts containing cercariae and metacercariae belonging to Monorchis Monticelli, 1893 were collected from naturally infected bivalves, Cerastoderma glaucum (Bruguière, 1789), and adult forms of Monorchis spp. were collected from sparid fishes of the genus Diplodus. All specimens were collected in the Gulf of Gabès, southern Tunisia. The identities of the examined molluscs and fishes were determined via molecular barcoding of their COI gene. Sequences of COI and ITS1 genes were also obtained for both larval and adult stages of collected parasite specimens. Genetic sequence data generated for the collected larval specimens only differed minimally from the sequence data of adults identified as Monorchis parvus; we attribute the difference to intraspecific variation. The morpho-anatomical study showed that the different stages of M. parvus collected from the Tunisian coasts had the same morphology as those reported in European waters with a lag in maturity and lower measurements. The species is recorded and molecularly characterised for the first time off the Tunisian coasts. [ABSTRACT FROM AUTHOR]

Aim. The aim of the study was to compare the specificity and sensitivity of responses of stress and toxicity to Cpz in marine and freshwater species of bivalve molluscs. Methods. The bivalve molluscs Mytilus galloprovincialis and Unio tumidus were collected in Messina, Italy and Ternopil region, Ukraine correspondingly. Two low Cpz concentrations (Cpz I: 12 ng L–1; Cpz II: 12 (M. galloprovincialis) or 18 (U. tumidus) μg L–1) were administered to molluscs for 14 days. The set of 16 studied parameters included the cytotoxicity indexes (lysosomal membrane stability, apoptotic enzymes caspase-3 and cathepsin D (CtD)), o xidative/reductive stress responses (superoxide dismutase (SOD) and catalase (CAT) activities, the levels of protein carbonyls (PC) and products of lipid peroxidation (TBARS), glutathione (GSH&GSSG), NAD+&NADH), metallothionein (total and Zn-bound) concentration, the biotransformation enzymes CYP450-dependent EROD, glutathione S-transferase (GST), and GTP-ase dynamin in the digestive gland with some inter-species differences in this spectrum. The applied spectrophotometric and chromatographic methods are described thoroughly in our previous work [6]. Results and Discussion. In the hepatocytes of rat, Cpz causes the biotransformation upregulation [7]. In our study, the activity of EROD increased both in M. galloprovincialis and U. tumidus, depending on the concentration and, particularly, in the Cpz II group of U. tumidus (by three times). This conversion of Cpz can result in the reactive metabolite formation [7]. According to this data, the inhibition or absence of the changes in the EROD activity in the Cpz I group of U. tumidus and Cpz II group of M. galloprovincialis can delay Cpz toxicity. On the other hand, the toxic product of biotransformation, quinoneimine is known to be eliminated by the GSH-dependent GST which activity was increased up to 63% in the Cpz I and II groups of marine mussels. Since in the freshwater mussels GST activity decreased in both exposures, the higher toxicity of Cpz was expected. Moreover, the GTP-ase dynamin activation in the Cpz I group of U. tumidus confirms the impact of this pharmaceutical on the clathrin-dependent endocytosis [8]. Conclusions. Summarizing, adverse outcome pathways related to the effect of Cpz on vertebrates in the μM concentration, were indicated in the mussels under the pM — nM concentrations with distinct inter-species concentration-related dependence, and the responses of stress were similar in both species. Particularly, marine molluscs can be a perspective model for evaluating Cpz adverse effects intrinsic for the higher vertebrates. [ABSTRACT FROM AUTHOR]

The article offers information on pen pearls from Bahrain, describing their origin, characteristics, and scientific examination. Topics include the geographical distribution and characteristics of pen pearls, the recovery of two pen pearls from Bahrain by a diver, their visual characteristics and structural details, and the analysis of their chemical composition and luminescence properties.

Marine lakes are bodies of seawater that are land-locked and maintain a subterranean connection to the surrounding sea. Here, we document the species diversity of benthic molluscs in 11 marine lakes in Raja Ampat, West Papua, Indonesia, using the roving diving survey method. We specifically tested for relationships between species richness and lake size and the degree of connection to the surrounding sea, and tested potential environmental drivers of community structure. We recorded 73 species, belonging to the classes Gastropoda (48 species, comprising 36 genera and 25 families), Bivalvia (24 species, consisting of 17 genera and 12 families), and Polyplacophora (one species). Molluscs from marine lakes are a subset of species also occurring in coral, seagrass, mangrove, and rocky shore habitats in the open sea. We found lake communities to mostly consist of grazers and filter feeders. The number of mollusc species significantly increased with increasing connection to the surrounding sea, but not with increasing surface area, indicating that dispersal potential may be the main driving force. Furthermore, we observed no significant influence of the environment on the variation in mollusc species composition among marine lakes. Still, we observed certain species to be exclusively present in either high or low-connected lakes, indicating a potential effect of environmental filtering. Marine lakes provide a unique ecosystem for diverse mollusc assemblages and as such should be protected. [ABSTRACT FROM AUTHOR]

Bivalves Mollusks have a potential benefit which include protection from anemia due to its content of iron and vit B12 in addition they pose a threat in promoting the ability to be contaminated by different heavy metals residues as a result of mining, industrial production untreated sewage sludge. Hg, Pb, Cd, As and Cr are the main five toxic heavy metals that induce human poisoning. For evaluation of Hg, Pb, Cd, As and Cr residues in Bivalve Mollusks in Fayoum province and their potential hazards, a total of 64 random samples of Bivalve Mollusks (Callista Florida species) were collected from the fish markets of Fayoum City, (Wadi Elrayan), Egypt The results revealed that the mean residues of Hg, Pb, Cd, As and Cr were 0.75, 0.77, 0.089, 7.285 and 0.011 mg/kg/ww, respectively. All samples examined for Hg and As exceeded the PML while Pb and Cd lied with the PML The collected samples were subjected to soaking in running water for 30 minutes; soaking in 5% acetic acid solution for 30 minutes and boiling with 5% acetic acid solution for 15 minutes .The heights reduction % of heavy metals residual levels were recorded after treatment in boiling 5% acetic acid treatment with the following reduction %; Hg (80%), Pb (67.6%), Cd (77.5%), As (44.35%) and Cr (75.76%). The assessment of Hazard quotient (HQ) and hazard index (HI) value was exceeded 1 which indicates a potential risk to human health and TR was > 1x10-4 which indicates a carcinogenic risk to the local consumers and will face high chronic risk if they consume Bivalve Mollusks on regular basis in their diet. [ABSTRACT FROM AUTHOR]

Shell microstructure and exquisite details of muscle attachment scars are preserved on the surface of internal moulds in the bivalve Fordilla troyensis from the Aftenstjernesø Formation (Cambrian Series 2, Stage 4) of North Greenland (Laurentia). Subsidiary muscles developed in commarginal series that extend laterally from the anterior and posterior adductor muscles probably controlled the centrally emergent foot. Their position close to the ventral margin indicates that only slight withdrawal and limited manipulation of the foot was possible, confirming that Fordilla was not a burrower. The pattern suggests derivation of Fordilla from a clamping mollusc with shell muscles distributed around the shell margin. No such pattern of serially repeated muscles close to the shell margin is currently known in the few available records of helcionelloid muscle scars, but Postacanthella has a commarginal U-shaped muscle scar reflecting its limpet-shaped shell form. Shell microstructure in Fordilla troyensis is closely similar to Pojetaia, with central areas of the valves dominated by a laterally continuous imbricate lamellar structure with a width of 10-20 µm between successive crests. Imbricate lamellae with about half this spacing form a marginal zone with crests lying perpendicular to the valve edge. The hinge line lacks teeth, although a single tooth is present in each valve of the related Fordilla sibirica and Fordilla germanica. The site of the simple ligament is coarsely striated. Comparative material of Fordilla troyensis is illustrated from New York State, North-East Greenland and Denmark. [ABSTRACT FROM AUTHOR]

The role of bivalve molluscs in the biological treatment of polluted natural waters is considered. The anatomical structure and tissue composition of these hydrobionts enabling the effective filtration and purification of water from suspended pollutants are given. It is shown that molluscs simultaneously create a biogenic water circulation that mixes water masses. Water absorption and circulation within the mantle cavity provides bivalve molluscs with oxygen and food necessary for respiration, which has a substantial effect on the biogenic migration of chemical elements in aquatic ecosystems. These circumstances make it possible to design special bioreactors that can be used, together with other hydrobionts, such as algae and bacteria, for biological treatment of natural reservoirs polluted by sewage. A plan has been drawn up to conduct experiments to study the rate of filtration and purification of contaminated water by bivalve mollusks. In this regard, the use of a bioreactor with bivalve molluscs in drinking water purification systems at the first stage of water treatment is worthy of attention. [ABSTRACT FROM AUTHOR]

The shell of a freshwater mussel (Mollusca: Bivalvia) is a composite biological material that plays an active role in maintaining ecosystem services. Mussel shells have variable structures both within and between species. In this study, the structural and biological characteristics of the shells of Potomida semirugata and Leguminaia wheatleyi were investigated in order to use freshwater mussel shells as a biological material. Close observation of the microstructure of the shells of the two common freshwater bivalves revealed a variation in construction from the outer periostracum to the inner nacreous layer. In P. semirugata, a polygonal arrangement with columnar prisms of different sizes was observed more significantly. In L. wheatleyi the prismatic columns are oval and irregularly polygonal. The nacreous layers of P. semirugata, in which the individual aragonite layers are horizontally overlapped, are more uniformly distributed. The overlapping of the aragonite sheets in L. wheatleyi is more irregular. The presence of calcium carbonate (CaCO3) in the shells was confirmed by the identification of the characteristic carbonate bands at 701.9, 713.5, and 865.8 cm-1. This information was used to classify and distinguish the different layers of the shells, allowing interspecific comparisons and variations in the different layers. The results clearly showed that shell samples were highly biocompatible and nontoxic compared to the control group. This finding suggests that these materials have promising potential for use in various biomedical applications where biocompatibility is a critical factor. The results indicated that the shells of the freshwater bivalves P. semirugata and L. wheatleyi are biological materials with potential multiple applications for human well-being and environmental quality. [ABSTRACT FROM AUTHOR]

The reproductive biology of Mactra stultorum from the Gulf of Gabes was investigated monthly during a one-year period (2017). This study is the first study examining its reproductive biology during one-year in the south of Tunisia. The overall samples presented a balanced sex ratio, with males dominating among smaller individuals (< 22 mm) and females predominating in larger size classes (> 34 mm). The obtained total sex ratio (F:M) was equal to 1.03:1. The size at first maturity (SL50%) was 20.43 and 22.10 mm for males and females, respectively. The seasonal variations assessed through macro- and microscopic characteristics in the gonads of both sexes indicated a clearly defined annual reproductive cycle with a principal spawning peak during summer and a resting period during December and January. The reproduction of M. stultorum was strongly influenced by fluctuations in the seawater temperature, as reflected through the temporal variation in the gonadal cycle, condition index (CI) and tissue weight rate (TiWR). If managed properly, M. stultorum is expected to meet the domestic market demand through artisanal fishery. The adoption and implementation of rules, such as limiting the size of clams, is required to protect this new exploitable fishery resource. [ABSTRACT FROM AUTHOR]

We describe freshwater mollusks from the Olmos Formation, Campanian, Upper Cretaceous. The results were obtained from several specimens of mollusks, identified with two families of gastropods: Viviparidae (Viviparus sp.) and Physidae (Mesolanistes sp.), and three families of bivalves: Limidae (Pseudolimea sp.), Unionidae (Proparreysia sp., Unio sp., Unionelloides? sp., Plesielliptio sp., and Ostreidae (Ostrea sp.). Based on this taxonomic recognition, along with the associated fossil flora, it was possible to get a preliminary of the environment where the mollusks lived. The interpretation of the paleoenvironment resemble freshwater bodies adjacent to an estuarine system. Furthermore, the mixing of specimens of brackish and freshwater environments is indicative of a transport of some of these mollusks. The general view of the paleoenvironment where the mollusks inhabited is that of a transitional freshwater-estuarine in the Olmos Formation during Campanian times. [ABSTRACT FROM AUTHOR]

The present work is aimed at investigating the effects of seasonal changes and habitat conditions on reproductive state and gonadal development of two macrobenthic fauna. Echinometra mathaei and Tridacna squamosa were collected seasonally (summer and winter) in July 2019 and January 2020 from three sites along the Red Sea coast, Egypt: Hamraween, Sedy Malek, and Porto Ghalb. Sexual differences and gonadal maturation in the two species were determined by performing biopsies of their gonads followed by morphologic analyses. Hematoxylin and eosin–stained gonadal sections were examined and analyzed. In E. mathaei, reproductive behavior was more active in the summer than in the winter; in T. squamosa, reproductive behavior was active almost all the year, especially during the winter. The reproductive activity and gonadal maturation of both species were affected by environmental factors. The results indicated that temperature is a vital factor affecting the reproductive activity of both species. This study concluded that temperature fluctuations may pose significant challenges to coastal marine ecosystems. [ABSTRACT FROM AUTHOR]

The rise in anthropogenic impacts on the marine environment requires new water management. The use of a triadic approach (bioaccumulation, bioassay, and physiological biomarkers) has been shown to have good applicability for the comparative assessment of the environmental state of the Neva Estuary (Gulf of Finland, Baltic Sea). The novelty of the methodological approach of the study was that it involved both active and passive bio-monitoring methods for assessing the quality of estuarine environment. The classical analyses of metal concentration in bottom sediments, in field biota (fish and molluscs), and in caged molluscs were accompanied by a bioassay of sediment toxicity using amphipods. The physiological state of molluscs kept in cages was assessed according to two functional characteristics, such as cardio-tolerance and metabolic activity (oxygen consumption rate), after exposition in cages. The method of active monitoring (caging exposure with molluscs) as a measurement of parameters in clean molluscs has proven itself well in controlling the accumulation of both metals and oil products. Macroalgae that are abundant in estuarine ecosystems are also good indicators of metals, at least showing the transition from bottom sediments to the next level of food webs. Unionid molluscs were found to be a more sensitive and effective indicator of contaminant accumulation than dreissenid molluscs, characterized by a low tolerance to changeable environmental conditions in the estuarine ecosystem and rather high mortality in cages. Our results have shown that caging exposure with unionids can be a widely used methodological approach for the assessment of estuarine environmental quality through the determination of metal concentrations in molluscs and their physiological state. [ABSTRACT FROM AUTHOR]

Copyright of Revista de Arqueologia is the property of Revista de Arqueologia and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Natura Sloveniae: Revija za Terensko Biologijo / Journal of Field Biology is the property of Natura Sloveniae and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Humans have consumed bivalve molluscs, such as mussels, scallops and oysters, and used their shells since prehistoric times. However, there are still discoveries to be made and lessons to be learnt in areas including their unusual adhesion, optics and longevity. Michael Gross reports. Humans have consumed bivalve molluscs, such as mussels, scallops and oysters, and used their shells since prehistoric times. However, there are still discoveries to be made and lessons to be learnt in areas including their unusual adhesion, optics and longevity. [ABSTRACT FROM AUTHOR]

This paper reports new occurrence records of two bivalve species, Lutraria impar Reeve, 1854, and Meretrix lusoria (Röding, 1798) from the Odisha coast on the basis of the collection from Bahuda estuary, Ganjam, Odisha. The genus Lutraria Lamarck, 1799, was not yet reported from the State, and the report of Lutraria impar is the first report of the genus from the Odisha coast. These specimens were collected from the sandy seabed near the mouth of the Bahuda estuary in Odisha. [ABSTRACT FROM AUTHOR]

Edible bivalves constitute an important bioresource from an economic point of view, and studies on their immune responses to environmental pollutants are crucial for both the preservation of biodiversity and economic reasons. The worldwide diffusion of copper(I)-based antifouling paints has increased copper leaching into coastal environments and its potential impact on both target and nontarget organisms. In this study, immunotoxicity assays were carried out with short-term (60 min) cultures of hemocytes from the bivalves Mytilus galloprovincialis--a mussel dominant in the macrofouling community--and Ruditapes philippinarum--a clam dominant in the soft-sediment community--exposed to CuCl to compare the toxic effects on their immune responses. The LC50 values were similar, 40 μM (3.94 mg L-1) for the mussel and 44 μM (4.33 mg L-1) for the clam. In both species, apoptosis occurred after exposure to 1 µM (98.9 μg L-1) CuCl, the concentration able to significantly increase the intracellular Ca2+ content. Biomarkers of cell morphology and motility revealed microfilament disruption, a significant decrease in yeast phagocytosis and lysosome hydrolase (β-glucuronidase) inhibition beginning from 0.5 µM (49.5 μg L-1) CuCl in both the mussel and clam. The same concentration of CuCl affected biomarkers of oxidative stress, as a significant decrease in reduced glutathione content in the cytoplasm and inhibition of mitochondrial cytochrome-c oxidase (COX) were detected in both species. Comparison of the biomarkers showed that clam is more sensitive than the mussel regarding alterations to the lysosomal membrane and reactive oxygen species (ROS) production, which supports the potential harmful effects of antifouling biocides on the survival of nontarget pivotal species in the coastal community. [ABSTRACT FROM AUTHOR]