Group Of Molluscs Research Articles

Impact of climate change on the distribution and habitat suitability of the world’s main commercial squids

Climate change is expected to have major negative effects on marine life across phylogenetic groups. Cephalopods, however, have life history characteristics that suggest they may benefit from certain climate change scenarios. Of all cephalopods, squids reach the greatest biomasses; as a result, they are of substantial importance for human and predator consumption. To test the hypothesis that the effects of climate change are beneficial for commercial squid, we used species distribution models on climate scenarios for the period between 2000 and 2014, as well as the years 2050 and 2100 (RCP [representative concentration pathway] 2.6, 4.5, 6.0, and 8.5; CMIP5). Our results suggest that consequences of climate change scenarios are species specific. In the North Pacific and Northwest Atlantic, squid’s habitat suitability may increase (from + 0.83% [Doryteuthis pealeii] to + 8.77% increase [Illex illecebrosus]), while it is predicted to decrease in other regions (from − 1.03% [Doryteuthis opalescens] to − 15.04% decrease [Loligo reynaudii]). Increases in habitat suitability occurred mostly at higher latitudes (north of 50° N), while suitable habitat decrease was predicted for the tropical regions. These shifts in future habitat suitability were stronger under harsher emission scenarios. Starting in 2050 (with RCP scenarios 4.6, 6.0 and 8.5), as a result of warming of the Arctic, squid habitat may increase along both coasts of North America. In the Southern Hemisphere, squids may lose habitat with no poleward habitat alternatives to move into. Contrary to our hypothesis, these commercial squid do not stand to benefit from climate change. Since these squid are an important food source for marine megafauna and humans, it is imperative that climate change biogeographic impacts are considered for a sustainable management of this important group of molluscs.

Comparative analysis of the mitochondrial genomes of the family Mactridae (Mollusca: Venerida) and their phylogenetic implications

Taxonomy and phylogenetic relationships within the family Mactridae have remained debatable because of the plasticity of morphological characteristics and the lack of accurate molecular data, thereby resulting in abundant synonyms and taxa rearrangements. Mitochondrial genomes (mitogenomes) have been widely used as powerful tools to reconstruct phylogenies of various groups of mollusks; however, they have not been used for studying the phylogeny of mactrids specifically. In the present study, mitogenomes of seven Mactridae species, namely Mactra chinensis, Mactra cygnus, Mactra quadrangularis, Mactra cumingii, Mactrinula dolabrata, Raeta pulchella, and Raeta sp., were sequenced by Illumina high-throughput sequencing, and a comparative mitochondrial genomic analysis was conducted. The newly sequenced mitogenomes were double-stranded circular molecules, with all functional genes encoded on the heavy strand. All the new mactrid mitogenomes had two rRNA genes (12S and 16S), 13 protein-coding genes (PCGs) (atp6, cox1, cox2, cox3, cytb, nad1, nad2, nad3, nad4, nad4l, nad5, nad6, and atp8), and 22 tRNAs. The mitogenomes showed considerable variation in AT content, GC skew, and AT skew. The results of the phylogenetic analysis confirmed monophyly of the family Mactridae and suggested that genera Mactrinula, Spisula, Rangia, and Mulinia should not be placed under subfamily Mactrinae. Our results supported that potential cryptic species existed in Mactra antiquata. We also proposed subfamily Kymatoxinae should belong to the family Mactridae rather than Anatinellidae and Mactra alta in China should be Mactra cygnus. Additionally, conservation in functional gene arrangement was found in genera Mactra, Raeta, and Lutraria. But gene orders in S. sachalinensis and S. solida were quite different, questioning their congeneric relationship. Our results further suggested that the taxonomy within the family Mactridae requires an integrative revision.

First record of microplastic in the Brazilian sea hare Aplysia brasiliana Rang, 1828 (Mollusca: Aplysiidae)

The presence of plastic debris in the marine environment has reached massive levels in the past decades. In marine environments, microplastics can exist for hundreds of years and the presence of microplastics in this environment has been reported since 1970 and since then has been considered ubiquitous. Mollusks are being used as microplastic pollution indicators, especially in coastal areas and bivalves are more often used in microplastic-monitoring studies. On the other hand, gastropods are poorly used as indicators for microplastic pollution, even though they are the most diverse group of mollusks. The sea hares of the genus Aplysia are herbivorous gastropods, important model organisms commonly used in neuroscience studies, isolating the compounds in their defensive ink. Until today, there is no previous record of the presence of MPs in Aplysia gastropods. Therefore, this study aims to investigate the presence of microplastics in tissues of A. brasiliana found in southeastern Brazil. We collected seven individuals of A. brasiliana from a beach in southeastern Brazil, dissected them to isolate the digestive tract and the gills, and digested the tissues with a solution of 10 % NaOH. In the end, 1021 microplastic particles were found, 940 in the digestive tissue, and 81 in the gills. These results represent the first record of the presence of microplastics in the Brazilian sea hare A. brasiliana.

Effect of suspended sediment concentration on the clearance and biodeposition rates of an Australian freshwater mussel (Hyriidae: Alathyria jacksoni)

Abstract Freshwater mussels are an ancient group of molluscs that are considered ecosystem engineers because of the many important functions they perform, including biofiltration and biodeposition. Associations between mussel declines and increased sedimentation are well documented, but the direct effects of suspended sediment (SS) concentrations on mussel functioning are poorly understood. This study investigated the effects of SS concentrations on the clearance and biodeposition rates of the Australian hyriid river mussel Alathyria jacksoni. Clearance rates of algae and sediment and biodeposition rates were measured in aquaria containing 3 L of aerated water for 1 hr, with six different concentrations of SS (bentonite clay: 0, 1, 10, 40, 100 and 300 mg/L). Clearance rates were estimated using flow cytometry and chlorophyll‐a with both methods giving similar results. Biodeposition rates were estimated by weighing the mussel biodeposits at the end of each trial. We found that SS concentrations did not have a significant effect on the clearance rates of algae, which ranged from 0.033 to 0.438 L mussel−1 hr−1, with an overall median of 0.118 L mussel−1 hr−1. By contrast, increasing SS concentrations had a significant effect on the clearance of sediment from the water column, with clearance rates peaking at 10 mg/L and declining thereafter. Clearance rates of suspended sediment ranged from 0.046 to 0.512 L mussel−1 hr−1, with an overall median of 0.182 L mussel−1 hr−1. We further detected a significant effect of SS concentration on the production of biodeposits, with inorganic and organic content in the biodeposits increasing as sediment concentrations increased. These results indicated that as SS concentrations increase, A. jacksoni rejects more inorganic and organic material in the form of pseudofaeces. This added maintenance work may result in an energetic cost to the mussel, and have potential consequences for growth, reproduction, and survival. Finally, population estimates of A. jacksoni in the lower Ovens River, Australia were combined with the clearance rates observed in the experiment, to estimate the potential impact mussel populations have in the clearance of total suspended matter from the open water of an unregulated south‐eastern Australian lowland river. A. jacksoni occurred patchily throughout the 35‐km section of the river surveyed, with an average overall mean and maximum density of 0.68, and 35 individuals/m, respectively. We estimate that under scenarios of 1 and 300 mg/L SS, the lower Ovens River mussel population can potentially clear up to 2–4 ML water/day, which equates to c. 1–2% of the average daily discharge in late summer, while transferring around 5.4–15.6 kg/day dry weight of organic material to the river bed. Increased SS concentrations negatively affect freshwater mussels around the world and many respond by reducing their clearance rates, but this was not the case for A. jacksoni. Instead, A. jacksoni increased production of inorganic and organic biodeposits rejecting more food particles in the form of pseudofaeces. For A. jacksoni and other species showing this response, the added energetic cost has the potential to impact growth rates, reproduction, and population dynamics.

A molluscan class struggle: exploring the surprisingly uneven distribution of chemosymbiosis among two major mollusk groups

Many bivalves and gastropods from marine reducing environments such as deep ocean hydrothermal vents and seeps host chemosynthetic bacteria in a nutritional symbiosis. Despite their functional similarities, the distribution of chemosymbiosis in these two mollusk classes is surprisingly uneven: the number of bivalve species known to host chemosynthetic symbionts is more than twenty times that of gastropods, and chemosymbiotic bivalves are reported from a far greater diversity of marine habitats. Here we explore the potential drivers for this trend, including but not limited to physiological differences, habitat characteristics, and sampling bias. Sampling bias likely contributes to the magnitude of the observed discrepancy, but we posit that the phenomenon itself reveals how intrinsic (e.g. morphology) and extrinsic (e.g. organic matter availability) factors might have shaped the distribution of extant gastropod and bivalve associations. These observations also serve as an impetus for increasing investigation into gastropods and other mollusks from chemically reducing environments to better understand the evolution and ecology of chemosymbiosis among molluscan hosts.

Thermally-induced clumped isotope resetting in belemnite and optical calcites: Towards material-specific kinetics

The application of carbonate clumped isotope (Δ47) thermometry in deep-time is often limited by modification of the original temperature signal by thermal resetting. New modeling approaches to estimate the initial isotopic composition of partially reset calcites and maximal burial temperatures, however, open promising avenues in temperature reconstruction. Such approaches strongly depend on laboratory-derived kinetic parameters of calcite materials, which may differ in their microstructure, water content and distribution, and minor and trace element composition, and thus may have different resetting kinetics. The rostra of belemnites, an extinct group of mollusks with a wide temporal and spatial occurrence in the Mesozoic, have been extensively used for deep-time paleoclimate reconstructions using oxygen isotope geochemistry. Belemnites are also important targets for clumped isotope-based temperature reconstructions, but often are found to have reset Δ47 compositions. Here, we present results from heating experiments on belemnite rostral calcite and optical calcite and provide belemnite-specific kinetic parameters for clumped isotope resetting. We show that belemnite calcite is altered faster and at lower temperatures than optical calcite and all other calcites reported in previous studies. We suggest that fast initial resetting results from oxygen isotope exchange of belemnite calcite with internal skeletal water present as fluid inclusions or organic-derived water, a process completed within 2–4 min at the experimental temperatures used here. Extrapolation to geological timescales using different solid-state bond reordering models shows that belemnite calcite resetting starts at lower burial temperatures than brachiopod, spar, and optical calcites. This susceptibility to thermal resetting results in a measurable (+3 °C) increase of the apparent Δ47 temperature even under shallow to moderate burial conditions (i.e., 40–50 °C for 106–107 years timescales). Following the overprint to higher apparent Δ47 temperatures during burial, the belemnite Δ47 may further re-equilibrate during exhumation resulting in a decrease of apparent Δ47 temperatures. Such “retrograde resetting” is similar to what is observed for carbonatites and marbles during cooling, and may cause underestimation of the thermal resetting a sample experienced during its geological history. Overall, our results demonstrate the importance of material-specific kinetic parameters and we urge caution when interpreting Δ47-derived temperatures of biogenic carbonates from deep-time archives.

The Complete Mitochondrial Genome and Gene Arrangement of the Enigmatic Scaphopod Pictodentalium vernedei.

The enigmatic scaphopods, or tusk shells, are a small and rare group of molluscs whose phylogenomic position among the Conchifera is undetermined, and the taxonomy within this class also needs revision. Such work is hindered by there only being a very few mitochondrial genomes in this group that are currently available. Here, we present the assembly and annotation of the complete mitochondrial genome from Dentaliida Pictodentalium vernedei, whose mitochondrial genome is 14,519 bp in size, containing 13 protein-coding genes, 22 tRNA genes and two rRNA genes. The nucleotide composition was skewed toward A-T, with a 71.91% proportion of AT content. Due to the mitogenome-based phylogenetic analysis, we defined P. vernedei as a sister to Graptacme eborea in Dentaliida. Although a few re-arrangements occurred, the mitochondrial gene order showed deep conservation within Dentaliida. Yet, such a gene order in Dentaliida largely diverges from Gadilida and other molluscan classes, suggesting that scaphopods have the highest degree of mitogenome arrangement compared to other molluscs.

Радиационно-индуцируемое изменение массы наземного моллюска F. fruticum M. двух возрастных групп

There is a problem of a shortage of scientific data on radiation-induced effects in representatives of biota in connection with the expansion of the principles of the anthropocentric strategy of radiation protection. At the same time, international organizations on radiation protection issues support the initiative to study the effects of ionizing radiation not only on reference organisms, but also on other representatives of the biota. The purpose of this work is to study the effect of acute -irradiation on the biomass of the terrestrial mollusk F. fruticum M. two age groups to expand databases on radio-induced effects of biota. Mollusks are widely used in biological control of radioactive contamination, and the change in the mass of mollusks can be interpreted as a relevant indicator of "morbidity". The age of the mollusks was determined by the number of turns of the shell. Irradiation of mollusks was carried out in the range from 10 to 300 Gy in increments of 10 Gy. The study of the biomass index was carried out for 210 days after irradiation. The obtained results of a laboratory study for mollusks of the second and third age groups are part of an experiment aimed at identifying the features of radio sensitivity of representatives of terrestrial malacofauna. Throughout the experiment, in the control group (non-irradiated individuals), the dynamics of the mass of mollusks, characteristic of seasonal changes in natural conditions, is noted. At the same time, the absolute survival of animals in selected laboratory conditions is observed. Dose ranges with different manifestations of changes in the mass of mollusks were revealed. Radiation doses less than 100 Gy (second group) and 120 Gy (third group) do not induce a change in the studied indicator. Irradiation with doses of 110-150 Gy and 130-150 Gy initiates a decrease in the mass of mollusks of the second and third groups, respectively, during suspended animation. In the dose ranges of more than 150 Gy, a more complex dynamics of changes in the indicator was established depending on the time after irradiation and on the age group of mollusks. It is due to the peculiarities of the manifestation of radio sensitivity in animals of different ages.

Main patterns of radula formation and ontogeny in Gastropoda.

Gastropoda is morphologically highly variable and broadly distributed group of mollusks. Due to the high morphological and functional diversity of the feeding apparatus gastropods follow a broad range of feeding strategies: from detritivory to highly specialized predation. The feeding apparatus includes the buccal armaments: jaw(s) and radula. The radula comprises a chitinous ribbon with teeth arranged in transverse and longitudinal rows. A unique characteristic of the radula is its continuous renewal during the entire life of a mollusk. The teeth and the membrane are continuously synthesized in the blind end of the radular sac and are shifted forward to the working zone, while the teeth harden and are mineralized on the way. Despite the similarity of the general mechanism of the radula formation in gastropods, some phylogenetically determined features can be identified in different phylogenetic lineages. These mainly concern shape, size, and number of the odontoblasts forming a single tooth. The radular morphology depends on the shape of the formation zone and the morphology of the subradular epithelium. The radula first appears at the pre- and posttorsional veliger stages as an invagination of the buccal epithelium of the larval anterior gut. The larval radular sac is lined with uniform undifferentiated cells. Each major phylogenetic lineage is characterized by a specific larval radula type. Thus, the docoglossan radula of Patellogastropoda is characterized by initially three and then five teeth in a transverse row. The larval rhipidoglossan radula has seven teeth in a row with differentiation into central, lateral, and marginal teeth and later is transformed into the adult radula morphology by the addition of lateral and especially marginal teeth. The taenioglossan radula of Caenogastropoda is nearly immediately formed in adult configuration with seven teeth in a row.

Molecular phylogeny of selected dorid nudibranchs based on complete mitochondrial genome

Dorid nudibranchs are a large group of mollusks with approximately 2,000 recorded species. Although agreement exists on the monophyletic nature of the dorid nudibranch group, the interfamily relationships of the suborder are subject to debate. Despite efforts to elucidate this issue using short molecular markers, the conclusiveness of the findings has been hindered by branching polytomy. Mitogenomes are known to be effective markers for use in phylogenetic investigations. In this study, eight mitogenomes of dorid nudibranchs were decoded and analyzed. Gene content and structure showed little change among species, reflecting the conserved mitogenomes of dorid nudibranchs. For most genes, the direction was typical for nudibranchs; nevertheless, tRNACys had an inverse direction in Cadlinidae species. Phylogenetic trees based on nucleotide and amino acid datasets revealed a relatively consistent pattern of interfamily relationships with little difference for positions of Phyllidiidae and Cadlinidae. Species of Cadlinidae were clustered together and did not form a clade with Chromododidae. Additionally, Goniodorididae was sister to Aegiridae, whereas Discodoridae was sister to Dorididae. This finding was supported by tree topology test based on mitogenome data. The results of the present study indicate that complete mitogenomes are promising markers for investigating interfamily relationships among dorid nudibranchs.

ВЛИЯНИЕ ИНВАЗИВНОГО ВИДА UNIONICOLA YPSILOPHORA (BONZ, 1783) НА МОРФО- И ИММУНОФИЗИОЛОГИЧЕСКИЕ ПОКАЗАТЕЛИ МОЛЛЮСКА ANODONTA CYGNEA (L.) РЫБИНСКОГО ВОДОХРАНИЛИЩА

The effect of the invasive biological species of the Rybinsk Reservoir, the water mite Unionicola ypsilophora (Bonz, 1783) on the morphological and immunophysiological parameters of the infected bivalve mollusks Anodonta cygnea (L., 1758), was studied. The dependence of mollusk infection by water mite on the age, size, fatness coefficient, somatic indices of gills, legs, the content of immune complexes and malondialdehyde, one of the final products of lipid peroxidation, is shown. Indicators of size, total weight, content of immune complexes and malondialdehyde in infected individuals aged 7–10 years significantly exceeded those of uninfected young children 4-5 years old. It is concluded that with age, the level of innate mechanisms of the anti-acaricidal immunity of A. cygnea to water mite decreases, which leads to mass infection and death of older age groups of mollusks. The obtained data can be used to predict the propagation rate of biological invasion of U. ypsilophora in water bodies.

Predicting changes in molluscan spatial distributions in mangrove forests in response to sea level rise.

Mollusks are an important component of the mangrove ecosystem, and the vertical distributions of molluscan species in this ecosystem are primarily dictated by tidal inundation. Thus, sea level rise (SLR) may have profound effects on mangrove mollusk communities. Here, we used dynamic empirical models, based on measurements of surface elevation change, sediment accretion, and molluscan zonation patterns, to predict changes in molluscan spatial distributions in response to different sea level rise rates in the mangrove forests of Zhenzhu Bay (Guangxi, China). The change in surface elevation was 4.76–9.61 mm year−1 during the study period (2016–2020), and the magnitude of surface‐elevation change decreased exponentially as original surface elevation increased. Based on our model results, we predicted that mangrove mollusks might successfully adapt to a low rate of SLR (2.00–4.57 mm year−1) by 2100, with mollusks moving seaward and those in the lower intertidal zones expanding into newly available zones. However, as SLR rate increased (4.57–8.14 mm year−1), our models predicted that surface elevations would decrease beginning in the high intertidal zones and gradually spread to the low intertidal zones. Finally, at high rates of SLR (8.14–16.00 mm year−1), surface elevations were predicted to decrease across the elevation gradient, with mollusks moving landward and species in higher intertidal zones blocked by landward barriers. Tidal inundation and the consequent increases in interspecific competition and predation pressure were predicted to threaten the survival of many molluscan groups in higher intertidal zones, especially arboreal and infaunal mollusks at the landward edge of the mangroves, resulting in a substantial reduction in the abundance of original species on the landward edge. Thus, future efforts to conserve mangrove floral and faunal diversity should prioritize species restricted to landward mangrove areas and protect potential species habitats.

Host phylogeny, habitat, and diet are main drivers of the cephalopod and mollusk gut microbiome

BackgroundInvertebrates are a very attractive subject for studying host-microbe interactions because of their simple gut microbial community and host diversity. Studying the composition of invertebrate gut microbiota and the determining factors is essential for understanding their symbiotic mechanism. Cephalopods are invertebrates that have similar biological properties to vertebrates such as closed circulation system, an advanced nervous system, and a well-differentiated digestive system. However, it is not currently known whether their microbiomes have more in common with vertebrates or invertebrates. This study reports on the microbial composition of six cephalopod species and compares them with other mollusk and marine fish microbiomes to investigate the factors that shape the gut microbiota.ResultsEach cephalopod gut consisted of a distinct consortium of microbes, with Photobacterium and Mycoplasma identified as core taxa. The gut microbial composition of cephalopod reflected their host phylogeny, the importance of which was supported by a detailed oligotype-level analysis of operational taxonomic units assigned to Photobacterium and Mycoplasma. Photobacterium typically inhabited multiple hosts, whereas Mycoplasma tended to show host-specific colonization. Furthermore, we showed that class Cephalopoda has a distinct gut microbial community from those of other mollusk groups or marine fish. We also showed that the gut microbiota of phylum Mollusca was determined by host phylogeny, habitat, and diet.ConclusionWe have provided the first comparative analysis of cephalopod and mollusk gut microbial communities. The gut microbial community of cephalopods is composed of distinctive microbes and is strongly associated with their phylogeny. The Photobacterium and Mycoplasma genera are core taxa within the cephalopod gut microbiota. Collectively, our findings provide evidence that cephalopod and mollusk gut microbiomes reflect host phylogeny, habitat, and diet. It is hoped that these data can contribute to future studies on invertebrate–microbe interactions.

Immunological Cross-Reactivity Involving Mollusc Species and Mite-Mollusc and Cross-Reactive Allergen PM Are Risk Factors of Mollusc Allergy.

Marine molluscs are seafood consumed worldwide and could cause food allergies, while investigation on their sensitizing components and cross-reactivity seems to be rare. Furthermore, allergy to mites may result in anaphylaxis in mollusc-allergic individuals owing to their cross-reactivity. The aim of the study was to identify cross-reactive allergens and investigate the cross-reactivity between different mollusc groups and mite-mollusc. The extracted mollusc and dust mite proteins were separated by SDS-PAGE, and IgE-binding components were recognized by immunoblotting with sera from patients sensitized to mollusc and mite. Cross-reactivity of different mollusc groups and mite-mollusc was assessed using ELISA and inhibition ELISA. The results of the immune detection, ELISA, and inhibition ELISA indicated that different mollusc groups and mite-mollusc showed varying degrees of cross-reactivity. The most frequently recognized cross-reactive protein was paramyosin from different mollusc groups and dust mite, while cross-reactive allergen paramyosin in the mite extract was identified and evaluated by MS and Allermatch, respectively. Inhibition ELISA studies also revealed that paramyosin played an important role in molluscan and mite-molluscan cross-reactivity. These findings contribute to a better understanding of the cross-reactivity involving mollusc species and mite-mollusc, which can be used to assist in the diagnosis and treatment of mite- and mollusc-allergic disorders.

Geological stories from the journey of mollusks fossils in Java

The journey began in the Eocene with the presence of mollusk fossil in the Nanggulan Formation (near Yogyakarta) in Central Java. Many experts believe this was the early part of the Tethys system which might still be connected to the Tethys system in Europe.The oldest mollusk fossils type locality after Nanggulan is the Early Miocene Jonggrangan Formation in Kulon Progo near the city of Yogyakarta, which is dominated by the gastropod Haustator specimen. Molluscan paleontological studies of this type of locality reflect a restricted environment with less influence of the Tethyan system. Haustator are considered as the ancestor of the Turritellidae group, which is found mostly on Java Island, during the younger Tertiary to Quaternary Periods.The story continued to the Middle Miocene where the Tethyan realms indication was clearly observed by the presence of some typical Tethys species such as Volema and Babylonia from Nyalindung Formation, West Java. The regional sea level rise in this epoch (around 12 Ma) that was indicated by the presence of Vicarya as an index fossil, which occurrence was due to land submerging to become mangroves area. The fossil then quickly become extinct when the sea level dropped back.Late Miocene to Pliocene was like the transition period from the Tethyan realm to the Pacific realm, where the Tethyan fauna was no longer present. Only evolutional traces of the Middle Miocene mollusk fossils were observed. This continuous evolution is most clearly seen in Turritella cramatensis (late Miocene), Turritella acuticarinata (early Pliocene) and Turritella cikumpaiensis (late Pliocene) which was interpreted to have originated from Turritella angulata as their ancestors.Earth cooling environment that happened in the late Pliocene/early Pleistocene has led the diversity and evolution of a new group of mollusks, most clearly observed from the abundance of Turritella bantamensis in the Bojong Formation, Banten. The new Turritella group has a curved whorl that different from its predecessor with an angled whorl shape.Plio-Pleistocene tectonics event has ended the period of Java marine mollusks domination, then only freshwater mollusk fossils can be found in almost all Quaternary mollusks-bearing deposits.

Biodiversity of Bivalves in South Bintan Waters, Riau Archipelago, Indonesia

Bivalves is the second most diverse group of molluscs after gastropods, they are also one of the most important members in marine ecosystems. Their taxonomic classifications are based on their morphology which tend to represent adaptation responses to ecology. The samples of bivalves examined in this study were taken in the South Bintan waters by Marine Geological Research and Development Center, Bandung. Identification of the bivalves shell samples was with the aid of a microscope and NIS-Elements software and identified using an identification book. There were 34 species of bivalves found in South Bintan Waters belong to 14 families. The highest abundance was in Station 1 the location close to the overflow of the river and a harbor (1162.5 ind.m-2) and the lowest was in Station 10 the location Station 10 the location close to a small island which is usually used as a tourist spot (62.5 ind.m-2). Their diversity and eveness index were included in the medium category with H’ value of 0.58-4.12 and e value of 0.11-0.89 respectively. There was species dominance in Station 3 (Liralucina lyngei of Lucinidae) and 10 (Cardites bicolor of Carditidae) but not in other stations. Both species was the most frequent species. Bivalves in South Bintan waters showed many different morphologies which represented their adaptation. The bivalve shells found were of different morphology. There are several forms of bivalve shell morphology that have shape round like species Chama japonica, triangular like species Gemma gemma, fragile like species Dendostrea rosacea. The shell decorations found in the bintan Bivalves samples are Spinose, Commarginally, Commarginally and radially ribbed. The hinge teeth are heteroodont, isodont, and schizodont.

Marine temperatures underestimated for past greenhouse climate

Understanding the Earth’s climate system during past periods of high atmospheric CO2 is crucial for forecasting climate change under anthropogenically-elevated CO2. The Mesozoic Era is believed to have coincided with a long-term Greenhouse climate, and many of our temperature reconstructions come from stable isotopes of marine biotic calcite, in particular from belemnites, an extinct group of molluscs with carbonate hard-parts. Yet, temperatures reconstructed from the oxygen isotope composition of belemnites are consistently colder than those derived from other temperature proxies, leading to large uncertainties around Mesozoic sea temperatures. Here we apply clumped isotope palaeothermometry to two distinct carbonate phases from exceptionally well-preserved belemnites in order to constrain their living habitat, and improve temperature reconstructions based on stable oxygen isotopes. We show that belemnites precipitated both aragonite and calcite in warm, open ocean surface waters, and demonstrate how previous low estimates of belemnite calcification temperatures has led to widespread underestimation of Mesozoic sea temperatures by ca. 12 °C, raising estimates of some of the lowest temperature estimates for the Jurassic period to values which approach modern mid-latitude sea surface temperatures. Our findings enable accurate recalculation of global Mesozoic belemnite temperatures, and will thus improve our understanding of Greenhouse climate dynamics.

Complete mitochondrial genome sequence and phylogenetic analysis of Arion ater (Stylommatophora: Arionidae)

Arion ater are a group of mollusks, almost all of which live in a dark and humid environment during their life cycle. In this study, the complete mitogenome of Arion ater was sequenced using next generation sequencing, analyzed and compared with other Stylommatophorans. The total length of the mitochondrial genome is 14,314 bp and consists of 13 protein-coding genes, 22 tRNA genes, 2 rRNA genes, and 1 control region. The genome has a typical mitochondrial gene sequence of Arion. Phylogenetic analysis of the mitochondrial genomes of 27 species of Stylommatophora showed that the Arion ater, Arion rufus and Arion vulgaris forms a monophyletic group with other species.

Возможности анализа хронических загрязнений водных источников с помощью биоэлектронных систем с двустворчатыми моллюсками

An independent experimental experience of observations of marine mussels (Black Sea mussel Mutilus galloprovincialis) since 2008 in the coastal zone and of freshwater mussels (pearl Unio pictorum) since 2014 at the river water intake point when developing and maintaining automated bioelectronic complexes at control facilities allowed accumulating data on valve activity in various natural conditions. The analysis of the data obtained determined statistical and methodological regional (Crimea) estimates of the valve activity of biosensor mollusks, including annual seasonal and climatic variability, daily and semi-daily periodicity and attenuation against the background of chronic toxicosis, starvation and physiological aging. Studies show that the main indicator of chronic pollution in water bodies for the developed automated biomonitoring systems is the level of group valve activity, which, in case of environmental toxicity, has a pronounced trend towards decline. Inter-annual variability can be analyzed by meeting a number of requirements for the composition and conditions of use of reference groups of mollusks, as well as by considering climate changes. The informativity, from the point of view of autonomous long-term automation of the control process, daily and semi-daily seasonal rhythms is quite doubtful, because they are unstable in the natural environment and depend on a number of natural factors unrelated to toxic pollution. It can be concluded that the main purpose of bioelectronic monitoring systems remains operational analysis and integrated indication of sudden impacts.

Aquatic ecosystems of the lower reaches of the Zarafshan River. Diversity and ecological groups of molluscs

Aquatic ecosystems of the lower reaches of the Zarafshan River revealed the distribution of 49 species and 2 subspecies of molluscs. They are distributed over aquatic ecosystems as follows: in the lower reaches of the Zarafshan River, 32 species and 2 subspecies are distributed, in the Navbakhorsky fish farm - 22 species and in the Khatyrchinsky fish farm - 15 species, in the Nurbuloksaysky fish farm - 22 species and in the Maidonsoysky - 18 species of mollusks. Their belonging to pelolymnophilic, peloreophilic, rheophilic, crenophilic, phytophilic, madicol, limno-crenophilic and telmatophilic ecological groups was considered.