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The stratigraphic scale of the Eastern Paratethys is revised based on a study of the Neogene stratotype and reference sections, their biotic characteristics, and paleomagnetic and sedimentological data. New data on the correlation of its regional subdivisions with the Central Paratethys and Mediterranean stratotypes are presented. The section “Regional Stage Scale of the Eastern Paratethys” considers the history of identification and a brief description of the horizons of the regional scale, which later became regional stages, as well as their historical stratotypes and lectostratotypes, and division into Beds and Substages. The section “History of Separate Biota Groups” provides reviews on the most important groups of fauna, phytoplankton, and terrestrial vegetation, as well as on magnetostratigraphy, the possibility of correlation and dating of sections based on these data, and comparison with the Central Paratethys and stratotypes of the Mediterranean. In conclusion, the main results of the revision of the stratigraphic scheme of the Neogene of the Eastern Paratethys are given.

The capability to produce pearls is widespread in the phylum Mollusca, including bivalves of the superfamily Unionoidea. Here, we identified and characterized natural pearls formed by Diplodon chilensis, a freshwater clam native to southern South America, using samples obtained from two lakes located in the Chilean Patagonia. Pearls were studied using light and scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and Raman spectroscopy. Naturally formed pearls were found in both male and female D. chilensis specimens. Pearls are produced in different shapes, including spherical, ellipsoidal, buttoned, and bumpy, ranging in size from 200 µm to 1.9 mm. The internal microstructure is composed of irregular polygonal tablets, about 0.40 to 0.55 μm in thickness. EDX analysis showed that pearls are composed of calcium carbonate. FTIR and Raman spectra recorded several peaks attributable to the aragonite in pearls of this species, as has been shown in other mollusks. In addition to these results, pearls of different colors are illustrated.

We are living in a time of rapid biodiversity loss. Numerous studies have shown that modern extinction rates are higher than pre-human background rates. However, these studies of biodiversity decline almost exclusively focus on large vertebrates. The scientific community lacks the sufficient long-term records necessary to track biodiversity loss for many invertebrate taxa. However, aquatic, benthic, and skeletonized invertebrates have the advantage of leaving a long-term record that can readily be sampled in conjunction with living communities because the mineralized skeletons accumulate in the very same sediments in which the animals that produced them once lived. These not-quite-fossil “death assemblages” contain an underutilized record for long-term monitoring. Here, we leverage three case studies of calcareous micro- and macro-faunal remains from three aquatic environments spanning two gradients: freshwater to fully marine and polluted to pristine and remediated. We compared the death assemblages to living assemblages in these case studies using Spearman’s rho and the Jaccard–Chao agreement to determine the degree of fidelity. Death assemblages of lacustrine, calcareous microcrustaceans (Ostracoda), collected from lakes in The Bahamas and Wisconsin, USA, faithfully record human impacts, both for degradation and remediation, as determined by a mismatch in the live–dead comparisons. Likewise, the live–dead comparisons of calcareous marine macrofauna (Bivalvia) from the southern California shelf also indicate human impact, including pollution and remediation. These case studies demonstrate how death assemblages can be used to gauge the changes in community assembly and population structures at local and regional scales, even in the absence of a systemic monitoring program. Conservation, restoration, and biomonitoring efforts would benefit from the inclusion of live–dead comparisons of taxa with easily fossilized, identifiable parts. Live–dead studies, such as those presented in these case studies, can be used as tools for recognizing targets and establishing baselines for conservation, tracking community responses to remediation efforts, and identifying local species extinctions.

Many studies have quantified the ecological impacts of individual foundation species (FS). However, emerging data suggest that FS often co-occur, potentially inhibiting or facilitating one another, thereby causing indirect, cascading effects on surrounding communities. Furthermore, global warming is accelerating, but little is known about how interactions between co-occurring FS vary with temperature. Shallow aquatic sedimentary systems are often dominated by three types of FS: slower-growing clonal angiosperms, faster-growing solitary seaweeds and shell-forming filter- and deposit-feeding bivalves. Here, we tested the impacts of one FS on another by analyzing manipulative interaction experiments from 148 papers with a global meta-analysis. We calculated 1942 (non-independent) Hedges' g effect sizes, from 11,652 extracted values over performance responses, such as abundances, growth or survival of FS and their associated standard deviations and replication levels. Standard aggregation procedures generated 511 independent Hedges' g that were classified into six types of reciprocal impacts between FS. We found that (i) seaweeds had consistent negative impacts on angiosperms across performance responses, organismal sizes, experimental approaches and ecosystem types; (ii) angiosperms and bivalves generally had positive impacts on each other (e.g. positive effects of angiosperms on bivalves were consistent across organismal sizes and experimental approaches, but angiosperm effect on bivalve growth and bivalve effect on angiosperm abundance were not significant); (iii) bivalves positively affected seaweeds (particularly on growth responses); (iv) there were generally no net effects of seaweeds on bivalves (except for the positive effect on growth) or angiosperms on seaweeds (except for the positive effect on ‘other processes’) and (v) bivalve interactions with other FS were typically more positive at higher temperatures, but angiosperm-seaweed interactions were not moderated by temperature. Synthesis. Despite variations in experimental and spatiotemporal conditions, the stronger positive interactions at higher temperatures suggest that facilitation, particularly involving bivalves, may become more important in a future warmer world. Importantly, addressing research gaps, such as the scarcity of FS interaction experiments from tropical and freshwater systems and for less studied species, as well as testing for density-dependent effects, could better inform aquatic ecosystem conservation and restoration efforts and broaden our knowledge of FS interactions in the Anthropocene.

Seasonal economic rhythms represent a long-standing concern of archaeological scholarship. To detect these rhythms, archaeologists have often looked to bivalve shells. Bivalves grow their shells by accretion, so that the chemical properties (e.g., oxygen isotope composition) of a given growth band record environmental conditions (e.g., sea-surface temperature) at the time the band was formed. In this way, isotopic variations between successive growth bands record variations in sea-surface temperature throughout the year. These isotopic data are quantitative and the physical processes conditioning them are well understood. However, studies usually rely on semi-qualitative expert assessments of isotope 'profiles' on a case-by-case basis, limiting the reproducibility of each analysis, the comparability between studies, the size of datasets, and the scope of research questions. We present a fully modeled and automated framework for deriving statistically sound and reproducible estimates of harvest seasonality on the basis of isotopic data from shell material. This approach allows detailed characterization of the uncertainties inherent in isotopic determinations of seasonality, facilitates analysis of larger samples necessary to address intra- and inter-site and diachronic variability, and offers a principle for combining multiple lines of evidence while properly accounting for the uncertainties of each. We estimate a given shell’s death date (i.e., day of year) using oxygen isotope measurements taken at known positions along the shell growth axis, measured from the shell margin. We first convert each shell’s sequence of isotope measurements into a sequence of sea-surface temperatures, using a formula theoretically and experimentally validated for the species studied. Then, for each day of the year, we estimate the probability that the organism died on that day given the shell’s sequence of temperatures, using Bayes’ Theorem to invert the conditional distribution of ocean temperatures at that time of year at the expected collection locale, estimated by regression. Using similar reasoning, we apply a Bayesian mixture model to multiple shells sampled from the same location to estimate the annual distribution of shellfish harvest intensity for that location. In this study, we assume a constant mean growth rate (appropriate for some cases, e.g., Mytilus californianus in coastal California), but the model can just as well incorporate an empirically-derived species-specific relationship between growth rate and time of year. A Bayesian framework such as this can be extended to holistically address larger questions of site seasonality and flexibly incorporate a wide variety of seasonal/temporal indicators across the history of settlement at a site or within an entire region. Such study of complex human eco-management systems articulates well with the distinct but allied goals of paleoclimatologists working to refine high-resolution studies of individual archives, offering a window onto the spatial and temporal structure of human engagements with dynamic environments. Many published datasets already exist that could support such large-scale research aims, but for problems of intercomparability. The method presented here allows us to leverage these legacy datasets without costly physical reanalysis, while also providing a framework for updating analyses with the latest high-resolution results.

[spa] Debido a las condiciones ambientales y características biológicas únicas de los ambientes marinos antárticos, los efectos del cambio climático pueden ser devastadores y pueden reflejar el posible futuro a gran escala de los ecosistemas marinos. La Antártida es, además, un sumidero de algunos contaminantes como los elementos traza y la península Antártica se considera una de las zonas más afectadas por el calentamiento global de todo el planeta. El objetivo principal de esta tesis ha sido profundizar en el conocimiento de los ecosistemas bentónicos marinos antárticos estudiando las interacciones biológicas y el efecto del cambio global. En el bentos somero antártico, las esponjas dominan la comunidad siendo fuente de C para una serie de depredadores como el nudibranquio Doris kerguelenensis, un espongívoro generalista. En isla Decepción se observó la presencia de este sobre diversas especies de esponjas. El análisis de isótopos estables de C y N y de ácidos grasos de este molusco y las esponjas más abundantes de la zona, y de algunos productores primarios demostraron que el molusco se alimenta, aunque no exclusivamente, de las esponjas Dendrilla antarctica, Mycale acerata, Haliclona sp. y Axinella crinita. En un estudio previo en la Antártida se detectó un gradiente norte-sur en la concentración de elementos traza, siendo mayor al norte (con mayor presencia humana). En nuestro trabajo se detectaron elementos traza (Cr, Pb, Hg) en una comunidad bentónica a lo largo de la Península Antártica, demostrando que la concentración de estos estaba más influenciada por las condiciones locales que por el gradiente norte-sur de la actividad humana. Las esponjas mantienen una relación muy estrecha con su microbiota, la cual realiza funciones vitales para el animal. Se evaluó el efecto de un estrés térmico en la composición y estructura de la microbiota de las esponjas, siendo las esponjas antárticas más resistentes al estrés térmico que la de esponjas templadas y tropicales, aunque el efecto en la fisiología de la esponja es desconocido. Las esponjas utilizan metabolitos secundarios como compuestos de defensa. El perfil químico de la esponja Dendrilla antarctica mostró una alta variabilidad intraespecífica, y variabilidad en esponjas de diferentes islas. Se caracterizó un nuevo diterpeno, la decepcionina. En conclusión, el estudio de las comunidades bentónicas desde diferentes perspectivas nos ha permitido construir una imagen más amplia del funcionamiento y condiciones de estos poco conocidos habitantes de las aguas polares., [eng] Due to the unique environmental conditions and biological characteristics of Antarctic marine environments, the effects of climate change can be devastating and may reflect future scenarios for other regions. Antarctica is also a sink for some pollutants such as trace elements and the Antarctic Peninsula is considered among the most affected areas by global change on the planet. The main objective of this thesis is to deepen the knowledge of the Antarctic marine benthic ecosystems studying biological interactions and the potential effect of environmental change. In shallow Antarctic benthos, sponges often dominate the communities being a source of carbon for predators like the nudibranch Doris kerguelenensis, a generalist spongivore. In Deception Island it was found upon various species of sponges. Analyses of C and N stable isotopes and fatty acids of this mollusc, the most abundant sponges in the area, and some primary producers were performed. The mollusc feeds upon the sponges Dendrilla antarctica, Mycale acerata, Haliclona sp., and Axinella crinita, but not exclusively. In Antarctica, a previous study detected a gradient in trace elements, larger to the north (higher human presence) and decreasing towards the south. The presence of Cr, Pb, and Hg was analyzed here in a benthic community along the Antarctic Peninsula, demonstrating that the concentration of these elements was influenced by local conditions rather than by the north-south human activity gradient. Sponges maintain a very close relationship with their microbiota, which performs vital functions for the animal. To evaluate the effect of heat stress on their microbiota, experiments were carried out exposing sponges from different habitats to heat stress. The microbiota of the Antarctic sponges seems to be more resistant to heat stress than that of temperate and tropical sponges, although the effects on the physiology of the sponge remain to be investigated. Sponges use secondary metabolites as defensive compounds. The chemical profile of Dendrilla antarctica showed a high intraspecific variability, but also a differentiation in the predominant metabolites in sponges from different islands. A new diterpene, deceptionin, was characterized. In conclusion, the study of benthic communities from different perspectives has allowed us to build a broader picture of the functioning and conditions of these little-known inhabitants of polar waters.

Target-capture approaches have facilitated a rapid growth in the field of phylogenomics but few probe sets exist for mollusks, an exceptionally rich phylum with unparalleled ecological and morphological diversity. We designed and tested the first universal probe set using Phyluce to capture ultraconserved elements (UCEs) and exon loci from the Subclass Caenogastropoda - one of six major lineages of gastropods. The probe set consists of 29,441 probes designed to target 1,142 UCE loci and 1,933 exon loci (3,075 total). In silico analyses of our probe set yielded an average of 2,110 loci from genomes and 1,389 loci from transcriptomes of diverse caenogastropods, from which an average of 1,669 and 849 loci were retained respectively after screening to remove those that matched multiple contigs. Phylogenetic analyses of the loci extracted from transcriptomes produced well-supported trees very similar to those published based on transcriptomic analyses. Phylogenetic relationships estimated from loci extracted from genomes recover similar phylogenetic relationships, and indicate that the loci targeted with this probe set are informative for resolving deep phylogenetic relationships. An in vitro analysis of the probe set with the Epitoniidae, a diverse caenogastropod family of uncertain affinity and with poorly resolved evolutionary relationships, recovered a total of 2,850 loci. Although preliminary, the analysis of loci captured by our probe set for a small number of epitoniid taxa produced a well-resolved tree indicating that this probe set is also able to resolve relationships at shallower hierarchical scales. Together, the in silico and in vitro analyses indicate that target-capture enrichment with this probe set is a useful tool for reconstructing phylogenetic relationships across taxonomic levels and evolutionary time scales.

The characteristics of the Strait of Magellan promote the formation of unique environments, with diverse habitats and marine organisms. This fragmentation of the landscape generates diverse little-explored ecological associations, especially in the zone of sub-Antarctic islands of the Tierra del Fuego archipelago. One way to address this lack of knowledge is through the biotope characterization methodology, with ecological units composed of the habitat and the communities associated with these environments, obtaining data and information on the dominant and incidental taxonomic groups. This is a good research model to conduct baseline studies in coastal benthic marine environments.A data set in Darwin Core standard is presented of the species that make up the intertidal biotopes of Clarence Island (Tierra del Fuego Archipelago, south of the Strait of Magellan). This includes 50 identified species and the specific coordinates for each sampled location, with a total of 1400 georeferenced records. Mollusks were the most diverse taxon with 21 species, followed by algae (14 species). Sessile organisms such as the barnacles Elminius kingii and Austromegabalanus psittacus predominate in these ecosystems, followed by bivalve mollusks such as Choromytilus chorus and Mytilus chilensis, which together with Nacella magellanica and the alga Hildenbrandia sp. make up more than 50% of the total records. The inclusion of biotope patterns in this study complements the information on benthic marine flora and fauna in the intertidal zone, including new records for the coast in the Clarence Island area, which is within the boundary of the Kawésqar National Park.

When addressing the nature and origin of loess deposits and the associated environment as deduced from terrestrial mollusc faunas, Vojen Ložek produced a synthetic review of the state of the art at that time (Ložek, 1965a). This synthesis was one among several papers that he published the same year in English about “The loess environment in Central Europe” (Ložek, 1965c) or “Problems of analysis of the Quaternary nonmarine molluscan fauna in Europe” (Ložek, 1965b). It was mainly based on his own experience of investigating terrestrial molluscs in Czechoslovakian Quaternary deposits.

Peter Shurulinkov, Zdravko Hubenov, Stoyan Beshkov, Georgi Popgeorgiev (Eds). Biodiversity of the Bulgarian-Romanian section of the Lower Danube. Book review

The presence of a 13-desmethyl Spirolide C isomer (Iso-13-desm SPX C) is very common in some infaunal mollusks in Galicia contaminated with this toxin. Its possible origin by biological transformation was investigated by incubating homogenates of the soft tissues of limpets and cockles spiked with 13-desmethyl Spirolide C (13-desm SPX C). The involvement of an enzymatic process was also tested using a raw and boiled cockle matrix. The enzymatic biotransformation of the parent compound into its isomer was observed in the two species studied, but with different velocities. The structural similarity between 13-desm SPX C and its isomer suggests that epimerization is the most likely chemical process involved. Detoxification of marine toxins in mollusks usually implies the enzymatic biotransformation of original compounds, such as hydroxylation, demethylation, or esterification; however, this is the first time that this kind of transformation between spirolides in mollusks has been demonstrated.

Salinity is an important ecological factor affecting the osmolality of aquatic animals. Solenaia oleivora is an endemic and economically important freshwater shellfish in China. However, its osmotic response and osmoregulatory mechanisms under high salinity stress are still unclear. In this study, S. oleivora was exposed to saline water (salinity: 2.2‰) for 3 h, 6 h, 12 h, 24 h, and 48 h, and then the changes in osmolality, ion concentrations, free amino acid (FAA) content, Na+/K+-ATPase (NKA) activity, and gill histology were analyzed. The hemolymph osmolality increased from 3 h after salinity stress and stabilized between 24–48 h. Na+ in the hemolymph increased from 24 h after salinity stress, and Cl− increased from 3 h. The content of total FAAs in the hemolymph increased after salinity stress. The content of alanine, glycine, glutamine, proline, and other FAAs increased after salinity stress. NKA activity in the gill, hepatopancreases, adductor muscle, and axe foot decreased during 3–48 h of salinity stress. The gill filament space increased and the number of gill cilia decreased after salinity stress. Principal component analysis (PCA) showed that the first two principal components (PC1 and PC2) cumulatively explained 77.6% of the total variation. The NKA activity was positively associated with PC1, while the ion concentration and most FAAs were negatively associated with PC1. Thus, these results indicated that S. oleivora is an osmoconformer, and inorganic ions, FAA, NKA, and gill structure changes play an important role in its osmoregulation.

The life cycles and biodiversity of Pacific coast gastropods were analyzed by videomicroscopy and DNA barcoding of individuals collected from tide pools and in plankton nets from a variety of shore stations. In many species (Families Calyptraeidae, Cerithiopsidae, Strombidae, Vermetidae, Columbellidae, Nassariidae, Olivellidae, Hermaeidae, Onchidorididae, Gastropteridae, Haminoeidae), the free-swimming veligers were recovered from plankton collections; in Roperia poulsoni (family Muricidae) veligers were usually recovered from egg sacs where they had been retained although some escapees were found in plankton collections; in Pteropurpura festiva (family Muricidae) free-living veligers were also found; and in Atlanta californiensis (family Atlantidae) both veligers and adults were obtained from plankton collections making this a holoplanktonic species. The results confirm that DNA barcoding based on COI gene sequencing is a useful strategy to match life-cycle stages within species as well as to identify species and to document the level of biodiversity within the gastropods.

Twenty-five years of paralytic shellfish poisoning (PSP) toxicity in Galician bivalves have been studied. PSP was detected in 4785 out of 73,740 samples of the commercially important bivalve species analyzed from 1995 to 2020. Its general prevalence in the area was 6.5%. Only 1.6% of all samples tested were over the regulatory limit (incidence). The maximum level of PSP in the area, 40,800 µg STX 2HCl-eq kg−1, was recorded in raft mussels from Bueu (PON-II, Pontevedra) in December 2005. The highest maximum PSP values were found in mussels, which were mostly affected by Gymnodinium catenatum, but not those of prevalence and incidence which were recorded in clams, mostly affected by Alexandrium. Average levels in mussels were higher than in any other studied species. Spatially, in general, the prevalence, incidence, maximum, and average PSP toxicity during episodes tend to decrease from south to northeast, but some hot points with high levels can be identified. PCA analysis separates the southern rías, associated to G. catenatum blooms, from the middle and northern ones, associated to Alexandrium blooms. Along the year, two main peaks of the four variables are observed, the first one in late autumn–winter and the other in summer, the summer peak being much more important for the infaunal species than for raft mussels. In the seasonal pattern obtained by time series analysis of the average PSP toxicity, the autumn-winter peak was only maintained (and very reduced) in the southern rías, indicating that this peak is seasonally much less important than the summer peak. The observed seasonality is expected based on the timing of the blooms of the two PSP-producing phytoplankton groups present in the area. Over the 25 years of monitoring, large differences in PSP toxicity have been observed. Apart from some special years, an ascending trend in prevalence and incidence seems to be present from 2011 to 2020. No trend seems to exist during the same period for average or maximum toxicity.

The continuing debate around the presence of vertebrate-type steroids in molluscs as well as their possible involvement in invertebrate reproduction and development reflects the gap of knowledge that exists within molluscan endocrinology. Although previous attempts in addressing the occurrence of vertebrate-type steroids in molluscs as well as the expression of steroidogenic genes in molluscan tissues are informative, doubts remain as to whether these steroids possess a functional role. Missing is a systematic evidence map on the presence of sterols and steroid hormones (vertebrate-type and invertebrate-type) in Mollusca as well as on the expression of steroidogenesis-related genes (including transport proteins and enzymes involved in the production and breakdown of retinoids) in these species. Furthermore, a systematic search of the literature on the expression of nuclear hormone receptors and nuclear retinoid receptors will also be conducted in the hopes of developing a better understanding on the function of NRs and their role in molluscan sex hormone biosynthesis. This systematic evidence map aims to: (1) provide a comprehensive assessment of our current understanding of sex hormone biosynthesis in molluscs, through an appropriate evaluation of all available evidence that exists in the literature and (2) highlight gaps in our knowledge for future research. This draft protocol is now being published on the open repository Zenodo as part of an 'open peer review' process. The wider scientific community is invited to comment on the systematic mapping methodology aimingto collect and assess literature that addresses the occurrence of different sex hormones in molluscs as well asthe expression of nuclear hormone receptors and steroidogenesis related genesin molluscan tissues. Please send your comments and feedback using this form until Wednesday 28/07/202123:00 (CET).&nbsp

Data about specific structure, distribution and also about mollusks quantity and biomass of the Tilligulski estuary are given. It was also conducted the comparison of received information with past years investigation., В работе представлены данные о видовом составе, распределении, а также о численности и биомассе моллюсков низовьев Тилигульского лимана и проведено сравнение полученных данных с исследованиями прошлых лет., У роботі наведено дані про видовий склад, чисельність та біомасу молюсків пониззя Тилігульського лиману і дано порівняння цих показників з результатами досліджень минулих років.

Limnoperna fortunei is an invasive exotic bivalve with high reproductive capacity and geographic distribution. Even after three decades of its introduction in South American waters, knowledge about ecological interactions as parasite/host for the species is still scarce in the literature. Therefore, the aim of this study was to investigate the presence of potential parasites in the golden mussel in the Lower Rio Grande Basin. The first step was the dissection of 1.000 L. fortunei from four stretches of the Rio Grande, where the internal and external demibranchs, mantle, gonads, and foot were inspected. The second stage, occurred by photostimulation (1 halogem lamp, 60W, 1 warm white fluorescent lamp 20 W and cool white fluorescent lamp 20 W) where 100 mollusks were exposed, distributed in four species, L. fortunei, C. fluminea, M. tuberculate and a single native representative P. canaliculata. No parasites were found in the exotic bivalve L. fortunei dissected and photostimulated. These results were extended to the other two exotic species C. fluminea and M. tuberculate. Only one specimen of the native species P. canaliculata showed a prevalence of cercaria of less than 1%. In view of these results, we can infer that the absence of parasites in the exotic mollusks and the presence in the native species may be an indication of some level of relationship with the dilution effect hypothesis. This is based on the premise that parasite pressure is diluted in the face of host diversity and the enemy release hypothesis which suggests that exotic species leave their natural enemies behind. Limnoperna fortunei es un bivalvo exótico invasor con una gran capacidad de reproducción y distribución geográfica. Incluso después de tres décadas de su introducción en aguas sudamericanas, el conocimiento sobre las interacciones ecológicas con una especie parásito/huésped es aún escaso en la literatura. Por ello, el objetivo de este estudio fue investigar la presencia de posibles parásitos en el mejillón dorado de la Cuenca del Bajo Río Grande. La primera etapa consistió en la selección de 1.000 ejemplares de L. fortunei de cuatro tramos del Río Grande, donde se inspeccionaron las demibranquias internas y externas, el manto, las gonodas y el pie. La segunda etapa se produce mediante fotoestimulación (1 lámpara halógena de 60 W, lámpara fluorescente blanco cálido de 20 W y 1 lámpara fluorescente blanco frío de 20 W) donde se expusieron 100 moluscos, distribuidos en cuatro especies, L. fortunei, C. flumiea, M. tuberculata y un único representante autóctono P. canaliculata. No se encontraron parásitos en el bivalvo exótico diseccionado y fotoestimulado L. fortunei. Estos resultados se extendieron a otras especies exóticas C. fluminea y M. tuberculate. Solo un ejemplar de la especie autóctona P. canaliculata mostró signos de cercaria, con una prevalencia del parásito inferior del 1%, de estos resultados se puede deducir que la ausencia de parásitos en moluscos exóticos y la presencia en nativos podría ser una indicación de algún nivel de relación con la hipótesis del efecto de dilución. Esto se basa en la premisa de que la presión de los parásitos se diluye ante la diversidad de huéspedes y en la hipótesis de la liberación de los enemigos, lo que sugiere que las especies exóticas dejan a sus enemigos naturales. O Limnoperna fortunei é um bivalve exótico invasor com alta capacidade reprodutiva e distribuição geográfica. Mesmo após, três décadas de sua introdução em águas sul-americanas, conhecimentos sobre interações ecológicas como parasito/hospedeiro para a espécie ainda são escassas na literatura. Nesse sentido, o objetivo deste trabalho foi investigar a presença de potenciais parasitos no mexilhão dourado na Bacia do Baixo Rio Grande. A inspeção parasitária se deu por duas etapas, a primeira ocorreu por meio de dissecação de 1.000 exemplares de L. fortunei oriundos de quatro trechos do Rio Grande, onde inspecionou-se as demibrânquias interna e externa, o manto, gônadas e o pé. A segunda etapa, ocorreu por meio de fotoestimulação (1 lâmpada halógena 60W, 1 lâmpada fluorescente branca morna de 20 W e 1 lâmpada fluorescente branca fria de 20 W) onde foram expostos 100 moluscos, distribuídos em quatro espécies, L. fortunei, C. fluminea, M. tuberculata e um único representante nativo P. Canaliculata. Não houve registro de parasito no bivalve exótico L. fortunei dissecados e fotoestimulados. Sendo esses resultados estendidos para as outras duas espécies exóticas C. fluminea, M. tuberculata. O registro de cercárias foi observado apenas em um exemplar da espécie nativa P. Canaliculata tendo uma prevalência parasitária inferior a 1%. Diante desses resultados, pode-se inferir que: a ausência de parasito nos moluscos exóticos e presença em nativo, pode ser um indicativo de algum nível de relação com a hipótese de efeito de diluição. Esta parte da premissa que a pressão parasitária é diluída frente a uma diversidade de hospedeiros e a hipótese de libertação do inimigo na qual sugere que espécies exóticas deixam para trás os seus inimigos naturais.

Research biases are common and constant issues in biological research, with major consequences for biodiversity conservation. Freshwaters represent one of the most threatened ecosystems worldwide, but knowledge of freshwater biota is unevenly distributed due to bias toward marine and terrestrial groups. Therefore, detecting biases and associated knowledge gaps is crucial to steer future research effort and to guide applicable conservation policies for freshwater ecosystems. In this study, we investigated the existence of biases and gaps in knowledge about the biodiversity of invertebrate fauna (zooplankton, mollusks and freshwater crabs) in the hydrographic regions of Brazil. We searched for all studies published in this country on zooplankton, mollusks and freshwater crabs, in the Web of Science database. Subsequently, the number of papers was classified by taxonomic group and hydrographic region to detect research biases. Each report within a paper between a given taxonomic group and a hydrographic region was termed as a case. We also recorded human population density for each hydrographic region. Among the taxonomic groups, zooplankton was the most studied taxon, followed by mollusks and crabs, and it was also dominant across the hydrographic regions. The hydrographic region of Parana comprised the largest number of cases for the three invertebrate groups. We detected a disproportionately low increase of number of cases in relation to human population density in the hydrographic regions. The identification of the major gaps reported here limits our ability to draw scenarios for the conservation of hydrographic regions and their megadiverse biota in Brazil.

Practical applications of environmental DNA (eDNA) are in exponential expansion, especially for the assessment and monitoring of freshwater metazoans. Because eDNA sampling and analysis is noninvasive, it improves the detection of threatened, invasive, and exploited species for which monitoring may be challenging. Species detection efforts using a combination of eDNA and qPCR have been highly successful and, as a result, their use in species monitoring is expanding rapidly. We developed qPCR primers and probes in order to monitor many invasive, threatened, or exploited aquatic species as part of various monitoring eDNA projects in the province of Québec, Canada. Here, we present a total of 60 species‐specific qPCR assays (including PCR protocols, primers, and TaqMan probes sequences) developed for the detection of 45 fishes, six amphibians, five reptiles, two mollusks, and two crustaceans. These comprised nine and 27 species, respectively, listed as invasive and threatened in Eastern Canada. These resources should be of broad usefulness not only for monitoring studies based in Québec but throughout the geographic range of the targeted species in North America.

The purpose of the research is to study of the morphological and biological characteristics of parthenogenetic and dioecious generations of the trematode Schistosoma turkestaniсum – a parasite of mammals of Uzbekistan.Materials and methods. Populations of mature trematodes from animals and mollusks Lymnaea auricularia from different types of water bodies of Uzbekistan were collected and studied. Experimentally reproduced the development of trematodes in the body of the intermediate and definitive hosts according to generally accepted methods.Results and discussion.The morphological and biological features of all phases of the development of Sch. turkestanicum under experimental conditions. Some new data on the morphology of the parasite having taxonomic meanings and the distribution of Sch. turkestanicum in Uzbekistan.

The purpose of the research is to study of the infection rate of freshwater mollusks and carp fish by trematodes transmitted by fish in the Psel and Seym basins in the Kursk region.Materials and methods. Helminthological material was collected from caught mollusks and fish. Mollusks were explored by the methods of life-time diagnostics and compression, and the fish by the method of compressing the spinal muscles and microscopic examination according to the method commonly used in helminthology. It was examined 200 specimens of mollusks and 1030 specimens of 6 fish species from the Cyprinidae family, from underyearling to two years of age. The species composition of trematodes was determined by identification guide.Results and discussion. Totally 4 species of helminths belonging to the Opisthorchidae: Opisthorchis felineus, Pseudamphistomum truncatum, Metorchis bilis and M. xanthosomus were identified. The extensiveness of infection by the larvae of O. felineus varied from 6.0 to 14.3 % in bleak, and 9.1% in red-eye. P. truncatum cysts were found only in bleak (8.0–11.1 %). The larvae M. bilis were found in 4 species of fish with extensiveness of infection from 5.6 to 50.0 %. 5 species of fish were infected by metacercaria M. xanthosomus (11.8–64.7 %). Epidemiological significance for humans have the first three species of the identified trematodes. The rate of fish infection indicates that the main source of opisthorchid eggs entering the examined river basins are wild and domestic birds, as well as semiaquatic mammals.

Our planet is home to an incredible array of species; however, relatively few studies have compared how anthropogenic threats impact taxonomic groups over time. Our objective was to identify temporal trends in threats facing the four most speciose phyla protected by the United States Endangered Species Act: angiosperms, arthropods, chordates, and mollusks. We determined presence or absence of threats for each species in these phyla by reviewing Final Rule listing decisions. For each phylum, we evaluated whether there was a linear, quadratic, or pseudo-threshold association between year of listing and the presence of 24 anthropogenic threats. We identified temporal trends for 80% of the 96 threat-phylum combinations. We classified threats as topmost (probability of being included in a species' listing decision peaking at ≥ 0.81) and escalating (probability of being included in a listing decision increasing by ≥ 0.81 between a species' first and most recent years of listing). Angiosperms, arthropods, and mollusks each had more topmost and escalating threats than chordates. Percentages of topmost threats were 42.9% (N = 21) for mollusks, 36.4% (N = 22) for angiosperms, and 33.3% (N = 21) for arthropods. Percentages of escalating threats were 22.7% (N = 22) for angiosperms and 14.3% (N = 21) for arthropods and mollusks. In contrast, percentages of topmost and escalating threats were only 4.2% (N = 24) for chordates, this one threat being climate change. Our research suggests potential conservation successes; some overutilization and pollution threats showed only gradually increasing or declining trends for certain phyla. We identified authorized take impacting angiosperms as the sole threat-phylum combination for which the threat had been consistently decreasing since the phylum's first year of listing. Conversely, species interactions, environmental stochasticity, and demographic stochasticity threats have seen drastic increases across all phyla; we suggest conservation efforts focus on these areas of increasing concern. We also recommend that resources be allocated to phyla with numerous topmost and escalating threats, not just to chordates.

Белки семейства PAX, обнаруженные у различных таксономических групп животных, играют важную роль в дифференциации клеток и органогенезе в процессе развития. Установлена связь некоторых представителей данного семейства белков с развитием сенсорных систем, в том числе, глаз у билатеральных животных, включая моллюсков. При этом для некоторых моллюсков характерна регенерация отдельных органов и тканей. Одним из таких моллюсков, способных к регенерации глаза, является Lissachatina fulica, геном которого до сих пор не аннотирован. Для определения участия в процессах регенерации представителей семейства PAX необходимо определить их аминокислотные последовательности. Поэтому целью данного исследования. Являлось биоинформатическое предсказание аминокислотных последовательностей белков семейства PAX в геноме Lissachatina fulica. В результате проведенной работы предсказано шесть потенциальных представителей семейства PAX — Afu019351, Afu013869, Afu008958, Afu015865, Afu016671 и Afu016672., PAX family proteins found in various taxonomic groups of animals play an important role in cell differentiation and organogenesis during development. The association of some members of this protein family with the development of sensory systems, including eyes in bilateral animals, including mollusks, has been established. At the same time, regeneration of individual organs and tissues is characteristic of some molluсks. One such molluсk capable of eye regeneration is Lissachatina fulica, whose genome has not yet been annotated; accordingly, to determine the involvement of members of the PAX family in regeneration processes, it is necessary to determine their amino acid sequences. The aim of this study was the bioinformatic prediction of the amino acid sequences of PAX family proteins in the Lissachatina fulica genome. As a result, we predicted six potential members of the PAX family: Afu019351, Afu013869, Afu008958, Afu015865, Afu016671, and Afu016672.

The study of sambaquis (ancient shell mounds) in conservation paleobiology is a complicated subject, especially when comparing body sizes of current and past mollusk valves to observe possible changes. There is a lack of information regarding how ancient fisher-gardeners collected these shellfish. Another obstacle is finding the hypothesis tests and data that can be used to compare current and past body sizes. To this end, we use the t-test (tt), Mann-Whitney (mw), and Bootstrap (bt) analyses to determine data scenarios for yellow clam (Amarilladesma mactroides) shells from two sambaquis units, and from two transects along the beaches of Rio Grande do Sul in southern Brazil. The study finds that the average body size of an Amarilladesma mactroides adult specimen is greater in sambaquis than the current valves across all tests (tt, p = 0.0005; mw, p = 0.006; bt, p = 0.04), even after reducing the sample number. However, when the comparison is only between valves that are larger than average, this does not hold true for two of the statistics (tt, p = 0.24; mw, p = 0.04; bt, p = 0.25). By refining the comparison for recent valves from different levels in the swash zone (upper, middle, and lower levels) with the past valves, we find that body sizes only differ at the middle level of the swash zone (tt, p = 0.004; mw, p = 0.004; bt, p = 0.005), where smaller adults, recruits, and juveniles live. This result could indicate that fisher-gardeners collected large organisms at distinct levels depending on the season (i.e., adults are collected in the upper level during summer and in the lower level during winter).

Panorama sobre el mundo de la malacología, desde el punto de vista de un aficionado naturalista, respondiendo a las siguientes preguntas: ¿qué se recoge?, ¿para qué?, ¿qué son los moluscos?, ¿cómo se clasifican?, ¿qué es la concha?, e incluyendo consejos generales para el coleccionista. Panorama sobre el món de la malacologia, des del punt de vista d’un aficionat naturalista, responent a les següents preguntes: què es recull?, per a què?, què són els mol·luscos?, com es classifiquen?, què és la petxina?, i incloent consells generals per al col·leccionista. An overview of the world of malacology, from the point of view of an amateur naturalist, answering the following questions: what is collected?, What for?, What are mollusks?, How are they classified?, What is the shell?, and including general advice for the collector.

Citizen science (CS) expands the spatial and temporal scale of alien species records. As such, it has been recognized as a complementary tool in alien species management and large‐scale biodiversity conservation. The present study assessed the contribution of CS to the recording of marine alien fishes and mollusks in European marine waters by reviewing data available through the European Alien Species Information Network, portals, public databases, and scientific literature. In total, 8,513 CS records were retrieved, following a filtering procedure, and assessed. A positive relationship was found between CS records and time, with most of records being reported during the last decade. The presence of alien fishes was recorded by citizens in seven out of nine Marine Strategy Framework Directive (MSFD) subregions, while mollusks were recorded in all MSFD subregions. Most of the CS records of fishes were reported in the Mediterranean Sea and mostly in the Aegean‐Levantine Sea. Conversely, most of the CS records of mollusks were reported in NE Atlantic Ocean, mostly in the Greater North Sea. A key finding is that eight species were documented for the first time in European marine waters and other three were recorded outside of their known distribution range. The majority of CS reporting was funneled through scientific surveys in which the nature of CS participation was limited to data collection only. The main categories of citizen scientists included school children, students, divers, naturalists, and various volunteers. Overall, 88.5% of marine alien fishes and mollusks recorded by citizens were validated by taxonomical experts, and only 15.8% out of the validated records were supplemented with pictures. CS can contribute to early detection and enhance cost‐effectiveness of monitoring and surveillance programs regarding alien species in European seas. Still, it requires proper scientific support and adequate validation tools mechanisms.

Copper (Cu) is a ubiquitous trace element in the aquatic environment, and is usually found at low levels. Copper environmental concentrations can be altered as a result anthropogenic activities. Shellfish are useful bioindicators to ensure adequate environmental monitoring. Thus, the aim of the present study was as follows: (a) determine the LC50 of copper(I) chloride in grooved carpet shell (Ruditapes decussatus) collected in the Santa Gilla lagoon (Sardinia, Italy), and (b) analyze the antioxidant biomarkers in digestive gland and gills of same specimens exposed to different concentrations of the above-mentioned metal (0.045, 0.45, and 0.90 mg/L) for 96 h. A withdrawal period of 96 h was considered for the treated clam, carrying out the same biochemical analyses, superoxide dismutase (SOD), catalase (CAT), selenium-dependent glutathione peroxidase (Se-GPx), glutathione S-transferases (GSTs), and total glutathione (GSH+2GSSG) in the two tissues. Different time and dose responses of the antioxidant biomarkers were recorded in the digestive glands and gills. Oxidative stress biomarkers highlighted the ability of Cu to induce oxidative stress in R. decussatus. Clam, following the withdrawal period of 96 h, has not been able to achieve the control levels of all biochemical markers in the digestive gland and gills. R. decussatus can be a suitable model to assess the ecotoxicity of copper in aquatic ecosystems. These findings may advance knowledge on the role and the effects of copper on oxidative stress biomarkers in grooved carpet shell. The metal ecotoxicity response can be useful to perform accurate biomarker-based monitoring programs using this bivalve species.

International audience; During the late Miocene, the Andean-Amazonian region experienced drastic climatic and environmental changes, notably due to a major phase in the Andean uplift. The fossil record is virtually undocumented for this period in the Subandean Zone, where very few palaeoenvironmental and palaeontological investigations have been undertaken. Here, we describe plant remains (pollen, spores, and leaves), microfossils, mollusks, and vertebrates from the Ipururo Formation at Shumanza, San Martín, Peru. Twenty-nine plant families are identified from 164 pollen grains and 89 spores, among them Lycophytes, Monilophytes, and angiosperms (5 monocots and 18 eudicots). The pollen sample notably includes Grimsdalea magnaclavata, Palaeosantalaceaepites cingulatus, Echitricolporites spinosus, and Fenestrites longispinosus, pointing to a late Miocene-early Pliocene age for the TAR-27 locality (10.06-3.72 Ma). Leaf impressions, from nearby localities in the same section, document Malvaciphyllum sp. (Malvaceae), three morphs resembling Caryocaraceae, Fabaceae, Myrtaceae, and two unidentified 'Dicotyledonae' angiosperms. The mollusk assemblage is somewhat reminiscent of early-middle Miocene Pebasian faunas and dominated by gastropods (ampullariids, cochliopid, cerithioid, and planorbids). It also includes sphaeriid and unionoid bivalves. Vertebrate recovery is very poor, with a serrasalmine characiform and unidentified actinopterygian teeth. Fossil assemblages and sedimentary facies consistently testify to the dominance of riverine/alluvial forests and the persistence of a steady lowland rainforest close to the Andes less than 10.1 million years ago, without indication of (1) mangrove/marine environments or (2) high-elevation ranges in the close surroundings of Shumanza by that time. By coupling palynostratigraphy and lithostratigraphy, Shumanza fossil assemblages would be further assigned an early late Miocene age (10.1-ca. 8 Ma).

The polyamine putrescine (Put) is a ubiquitous small cationic amine. It plays an essential role in controlling the innate immune response. However, little is known about its function in mollusks. In this study, the Put content was observed to increase in the serum of pearl oyster Pinctada fucata martensii after 6 and 24 h of lipopolysaccharide (LPS) stimulation. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) increased, and nitric oxide synthase was downregulated in the Put group (i.e., combined treatment with Put and LPS) compared with that in the LPS group (i.e., combined treatment with phosphate-buffered saline and LPS). Furthermore, activities of alkaline phosphatase and acid phosphatase were inhibited after 6 h of LPS stimulation. The expression levels of the nuclear factor kappa B, IκB kinase, Janus kinase, and signal transducer and activator of transcription proteins genes were all significantly suppressed at 12 and 24 h in the Put group. Pseudomonas aeruginosa and Bacillus subtilis grew better after being incubated with the serum from the Put group than that from the LPS group. Additionally, the Put treatment remarkably inhibited the autophagy of hemocytes mediated by the AMP-activated protein kinase-mammalian target of rapamycin-Beclin-1 pathway. This study demonstrated that Put can effectively inhibit the inflammatory response induced by LPS in pearl oysters. These results provide useful information for further exploration of the immunoregulatory functions of polyamines in bivalves and contribute to the development of immunosuppressive agents.

Limestone–marl alternations are commonly used for high‐resolution cyclostratigraphic studies and palaeoenvironmental reconstructions, but diagenetic studies indicate that not all limestone–marl alternations reflect genuine differences in the initial sediment composition driven by environmental changes. Differences in the ratios of diagenetically inert trace elements between limestones and marls indicate changes affecting the terrigenous fraction of the precursor sediment. Contrarily, limestone–marl alternations without these differences can be the product of: (i) variations in CaCO3 input (aragonite, calcite); (ii) distortion of the latter by diagenetic CaCO3 redistribution; or (iii) diagenetic CaCO3 redistribution in a homogeneous precursor sediment. The aim of this study is to provide a method to differentiate these cases and to identify variations in the proportion of calcite and aragonite in the precursor sediment composition. The model of differential diagenesis assumes that the concentration of diagenetically inert elements is inversely proportional to the amount of redistributed CaCO3. Consequently, the difference between ratios of diagenetically inert elements from two adjacent beds is a measure for CaCO3 redistribution. This is quantifiable by the vector length between ratios from two adjacent beds. The approach is illustrated here by evaluation of a case study from the Silurian of Gotland, Sweden. Trace elements were compared according to their solubility during diagenesis. All elements bound to clay minerals or calcite show similar patterns of vector length, while vector length of elements which fit into the aragonite lattice, and are diagenetically mobile, differ. The vector length approach provides a tool to test the diagenetic origin of limestone–marl alternations, to identify initial variations in CaCO3 input and to test a limestone–marl alternation’s suitability for cyclostratigraphic analyses., Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, Research Foundation of Flanders

The Aptian Romualdo Formation in the Araripe Basin represents the establishment of an epeiric sea in the Brazilian Northeast during the Early Cretaceous. This unit is composed by a succession of limestones, shales, sandstones, and coquinas, which constitute shell beds near the top. This last interval strongly suggests a marine influence in the whole basin based on the fossil assemblage. However, even though the establishment of marine waters during the deposition of the Romualdo Formation is a consensus, paleogeographical and paleoenvironmental aspects still need to be better understood. This study aims to perform a sedimentological analysis of the coquina interval, based on petrographic and taphonomic analysis of field data and in a new fully recovered well-core (2-AB-1-CE) drilled in the Serra do Maozinha at Abaiara county in the Ceara State. The described rocks were subdivided into eight facies constituted by bivalves, gastropods, ostracods, peloids, micrite, siliciclastic grains, punctual foraminifers, and plant debris. Based on facies' vertical stacking at well 2-AB-1-CE, a main regressive pattern was observed. It was also possible to subdivide the coquina interval into high-frequency transgressive–regressive cycles. The regional distribution of the facies permitted the identification of a shallow epeiric sea throughout the basin, with variations in the paleoenvironment energy and siliciclastic input. These variations were mainly controlled by paleotopography, fluvial discharge, and sea-level oscillations. The data allowed the identification of two subsequent paleogeographical configurations controlled by sea-level change. The first one, related to a sea-level high, was characterized by a protected bay on the western border and a gulf in the rest of the basin. Then a sea-level fall led to the formation of closed and open lagoons associated with higher terrigenous supply. As such, this study adds new data for a better understanding of the Araripe Basin and the impacts of sea-level fluctuations in South America during the Aptian.

Plastic fragments < 5 mm, known as microplastics (MPs), are ubiquitously present in the marine environment. Research on MPs pollution has gradually shifted from field investigations to laboratory studies. With the rapid growth of plastic consumption and the prevalence of aquaculture products, studies on marine MPs have focused on key marine species, such as mollusks. This review summarizes the recent knowledge including 77 important relevant literatures (from 2010 to 2021) on MPs contamination in mollusks with the objectives of (1) elucidating the current status of MPs pollution levels in mollusks, (2) highlighting the main methods and techniques for separation, extraction, and identification of MPs in soft tissues of bivalves and (3) presenting the current research progress and future directions. The review visually presents some of the important results in graphic form, which shows that the most common polymer plastics in bivalves are polypropylene, polystyrene, and polyethylene, and the shapes were mainly fiber and threadiness, mollusks are more likely to feed smaller MPs, most of the MPs in bivalves are less than 500 μm, and the abundance of MPs in seawater and the abundance of MPs in mollusks have a positive relationship, etc. This review will provide a comprehensive reference for studies of microplastics in marine organisms and the ecological pollution, and also has scientific guiding significance in the research method.

Simple Summary In recent years, the use of antibiotics has increased worldwide in both human and veterinary fields. This led to them accumulating in the environment to such an extent that they are actually included in the category of contaminants of emerging concern. For this reason, many of them have been included in monitoring lists of potential pollutants by competent authorities in order to limit their concentration in surface waters and to determine the risk to the aquatic environments. From this perspective, the aim of this review is to update and discuss the available data on antibiotic residues, using bivalves as biomonitoring organisms. Bivalves are good candidate for this purpose, being globally present in large and accessible populations, sedentary and able to accumulate several xenobiotics thanks to their large filtration capacity. The current research indicates that antibiotics’ presence in bivalves has been investigated along European, American and Asian coasts. Except for tetracycline, determined at high concentration in the North Adriatic Sea, all antibiotics residues in bivalves were under the maximum residual limit established by the competent authorities. Nevertheless, further investigations are necessary in order to prevent antimicrobial resistance, preserve the environment from antibiotic pollution and monitor the associated risk for animals and humans. Abstract Antibiotics are used for therapeutic and prophylactic purposes in both human and veterinary medicine and as growth promoting agents in farms and aquaculture. They can accumulate in environmental matrices and in the food chain, causing adverse effects in humans and animals including the development of antibiotic resistance. This review aims to update and discuss the available data on antibiotic residues, using bivalves as biomonitoring organisms. The current research indicates that antibiotics’ presence in bivalves has been investigated along European, American and Asian coasts, with the majority of studies reported for the last. Several classes of antibiotics have been detected, with a higher frequency of detection reported for macrolides, sulfonamides and quinolones. The highest concentration was instead reported for tetracyclines in bivalves collected in the North Adriatic Sea. Only oxytetracycline levels detected in this latter site exceeded the maximum residual limit established by the competent authorities. Moreover, the risk that can be derived from bivalve consumption, calculated considering the highest concentrations of antibiotics residues reported in the analyzed studies, is actually negligible. Nevertheless, further supervisions are needed in order to preserve the environment from antibiotic pollution, prevent the development of antimicrobial resistance and reduce the health risk derived from seafood consumption.

Despite the great importance of gills for bivalve mollusks (respiration, feeding, immunity), the microbiota associated with this tissue has barely been characterized in scallops. The scallop Argopecten purpuratus is an important economic resource that is cultivated in areas where coastal upwelling is intensifying by climate change, potentially affecting host-microbiota interactions. Thus, we first characterized the bacterial community present in gills from cultivated scallops (by 16S rRNA gene amplicon sequencing) and assessed their stability and functional potential in animals under farm and laboratory conditions. Results showed that under both conditions the gill bacterial community is dominated by the phylum Campylobacterota (57%), which displays a chemoautotrophic potential that could contribute to scallop nutrition. Within this phylum, two phylotypes, namely symbionts A and B, were the most abundant; being, respectively, taxonomically affiliated to symbionts with nutritional functions in mussel gills, and to uncultured bacteria present in coral mucus. Additionally, in situ hybridization and scanning electron microscopy analyses allowed us to detect these symbionts in the gills of A. purpuratus. Given that shifts in upwelling phenology can cause disturbances to ecosystems, affecting bacteria that provide beneficial functions to the host, we further assessed the changes in the abundance of the two symbionts (via qPCR) in response to a simulated upwelling intensification. The exposure to combined decreasing values in the temperature, pH, and oxygen levels (upwelling conditions) favored the dominance of symbiont B over symbiont A; suggesting that symbiont abundances are modulated by these environmental changes. Overall, results showed that changes in the main Campylobacterota phylotypes in response to upwelling intensification could affect its symbiotic function in A. purpuratus under future climate change scenarios. These results provide the first insight into understanding how scallop gill-microbial systems adapt and respond to climate change stressors, which could be critical for managing health, nutrition, and scallop aquaculture productivity.

Background 5-Methylcytosine (5mC) is an important epigenetic mark in eukaryotes. Little information about its role exists for invertebrates. To investigate the contribution of 5mC to phenotypic variation in invertebrates, alteration of methylation patterns needs to be produced. Here, we apply new non-nucleoside DNA methyltransferase inhibitors (DNMTi) to introduce aleatory changes into the methylome of mollusk species. Results Flavanone inhibitor Flv1 was efficient in reducing 5mC in the freshwater snails Biomphalaria glabrata and Physa acuta, and to a lesser degree, probably due to lower stability in sea water, in the oyster Crassostrea gigas. Flv1 has no toxic effects and significantly decreased the 5mC level in the treated B. glabrata and in its offspring. Drug treatment triggers significant variation in the shell height in both generations. A reduced representation bisulfite-sequencing method called epiGBS corroborates hypomethylation effect of Flv1 in both B. glabrata generations and identifies seven Differential Methylated Regions (DMR) out of 32 found both in Flv1-exposed snails and its progeny, from which 5 were hypomethylated, demonstrating a multigenerational effect. By targeted bisulfite sequencing, we confirmed hypomethylation in a locus and show that it is associated with reduced gene expression. Conclusions Flv1 is a new and efficient DNMTi that can be used to induce transient and heritable modifications of the epigenetic landscape and phenotypic traits in mollusks, a phylum of the invertebrates in which epigenetics is understudied.

The present study was aimed to investigate the composition and contents and the major lipophilic compounds, including the sterols, fatty acids, and tocols of shellfish species. Moreover, to explore the antitumor activity of these lipophilic constituents, their cytotoxicity potentials were determined against five different human cancer cells, including colon carcinoma (HCT116), epithelial melanoma (A2058), glioblastoma multiforme (T98G), lung carcinoma (A549), and adenocarcinoma (HeLa). The results show a significant variation in the contents and composition of lipophilic constituents among the studied species. The highest omega-3 (n-3) polyunsaturated fatty acids (PUFAs) were recorded from arrow squid and pacific oysters, accounting for 53.2% and 53.0% of their total fatty acids, respectively. However, the highest cholesterol content was also recorded in arrow squid (154.4 mg/100 g, 92.6% of total sterols). In contrast, in the Japanese littleneck, Yesso scallop, and common orient clam, cholesterol was just 17.1%, 18.3%, and 18.9% of total sterols, respectively, making them the richest source of non-cholesterol sterols (NCS). Lipids extracted from shellfish species showed ABTS+•- and DPPH•-scavenging activities. In the cytotoxicity analysis, lipids extracted from the Argentine red shrimp showed the highest cytotoxicity against glioblastoma multiforme T98G cells, with an IC50 value of 12.3 µg/mL. The composition and cytotoxicity data reported herein may help explore the nutritional and anticancer potentials of shellfish species.

In order to promote knowledge in conservation and sustainable use of globally threatened mollusks, juveniles are being obtained in the laboratory for restocking and aquaculture production. P. arctata has a high potential for aquaculture because they feed on primary productivity, have early maturity, external fertilization, hermaphroditism and the possibility of finding mature organisms all year round. Despite these characteristics, in 2002 this species was included in the list of endangered species in Colombia in the vulnerable category (Ardila et al., 2002). This research seeks to expand the knowledge of P. arctata in terms of its reproductive biology and induced reproduction, evaluating the efficiency of different stimuli to induce spawning of the estuarine clam Polymesoda arctata in laboratory conditions, sexually mature. For this purpose, between December 2020 and March 2021, monthly collections of 100 adult specimens (greater than 35 mm in length) were made in the Ciénaga Grande de Santa Marta (10°43'-11°00' N and 74°16'- 74°38' W) and transported to the laboratory of Molluscs and Microalgae of the Universidad del Magdalena, Taganga, Santa Marta (11°16' N, 74°11' W), where they were acclimatized to laboratory conditions. A representation of fully mature or stage IV females was found between 7 and 57%, except in the month of February, when no females were found (Figure 1). In contrast, only fully mature males (between 33 and 80%) were found for the months of March and May. In spite of this, spawning specimens were obtained in all months of the study, except for females in February. Males had an average shell length of 35.5 ± 0.8 mm, while females had an average shell length of 39.0 ± 0.8 mm, and females were larger than males (gl = 1, F = 8.09, p = 0.0057). The effectiveness of all the methods applied was tested, finding spawning in P. arctata, demonstrating that serotonin at a concentration of 20 µM and KCL (only spawning in males), were the methods with positive results. As for spawning, the average percentage of clams spawned ranged from 0 to 16%. With the injection of serotonin placed in the foot at a low concentration of 20 µM, spawning was obtained in both sexes. In contrast, with KCl injection, only males spawned, while no spawning was obtained with the stimuli supplied to the water (UV-irradiated water flow, temperature and salinity changes). Higher percentages of spawned animals were found in those treated with serotonin at low concentration compared to the other 12 treatments (gl =9, F = 5.71, p < 0.0001). Among the methods, the time of onset of the spawning response after serotonin stimulation was between 22 and 37 minutes, with males responding faster than females in serotonin-stimulated organisms (gl =1, F = 18.43, p = 0.0002). Post-stimulation mortality of spawning-induced specimens ranged from 4 to 51%, being higher when a high serotonin concentration was used, either by piercing the shell or without piercing, compared to that obtained for the remaining treatments (gl = 4, F = 3.83, p = 0.0388). the best spawning percentage, response time and survival was obtained with 20 µM serotonin. 1. INTRODUCCIÓN 13 2. OBJETIVOS 14 2.1 Objetivo general 14 2.2 Objetivos específicos 14 3. JUSTIFICACIÓN 15 4. MARCO TEÓRICO 15 5. MATERIALES Y METODOS 17 6. RESULTADOS 20 6.1 Análisis de la madurez gonadal y tamaño de las almejas por sexo 20 6.2 Ensayos de inducción al desove 21 7. DISCUSIÓN 23 8. CONCLUSIONES 27 9. RECOMENDACIONES 28 10. BIBLIOGRAFÍA 28 ANEXOS 35 Figura 1. Estadio de madurez de hembras (A) y machos (B) de P. arctata colectados en la CGSM entre diciembre de 2020 y mayo de 2021. 20 Figura 2. Porcentaje de hembras y machos de P. arctata desovados luego de suministrar estimulación física o química. 21 Figura 3. Tiempo de inicio de la respuesta del desove de los machos y hembras de P. arctacta inducidos al desove con serotonina y KCl. 22 Figura 4. Porcentaje acumulado de mortalidad, (A) Perforados e inyectados con serotonina 2 mM, (B) inyectados en el pie con serotonina 2 mM, (C) inyectados en el pie con agua de mar, (D) inyectados en el pie con serotonina 20 µm y (E) expuestos a estímulos exógenos. 23 Figura 5. Lugar de recolección de reproductores ciénaga grande de santa marta sector pajarales. 35 Figura 6. Nevera plástica de transporte de almejas y zona de aclimatación de almejas (canaletas blancas de 200 L). 35 Figura 7. Abrasión de almejas. 36 Figura 8. Suministro de estímulos químicos. 36 Figura 9. Herramienta de velocidad variable (Mototol) para la perforación de concha. 37 Con el fin de promover conocimiento en conservación y aprovechamiento sostenible de moluscos amenazados a nivel mundial, está la obtención de juveniles en laboratorio para repoblación y producción por acuicultura. P. arctata tiene un alto potencial para la acuicultura debido a que se alimentan de la productividad primaria, tiene una madurez temprana, fertilización externa, hermafroditismo y posibilidad de encontrar organismos maduros todo el año, a pesar de estas características, en el año 2002 esta especie fue incluida en el listado de especies amenazadas en Colombia dentro de la categoría vulnerable (Ardila et al., 2002). Esta investigación busca la ampliación del conocimiento de P. arctata en cuanto a su biología reproductiva y reproducción inducida, Evaluando la eficiencia de diferentes estímulos para inducir el desove de la almeja estuarina Polymesoda arctata en condiciones de laboratorio, sexualmente maduros. Para ello entre diciembre de 2020 y marzo de 2021 se hicieron colectas mensuales de 100 ejemplares adultos (mayores a 35 mm de longitud) en la Ciénaga Grande de Santa Marta (10°43’-11°00’ N y 74°16’-74°38’ W) y se transportaban al laboratorio de Moluscos y Microalgas de la Universidad del Magdalena, Taganga, Santa Marta (11° 16’ N, 74° 11’ W), donde se aclimataron a las condiciones de laboratorio. se encontró una representación de hembras completamente maduras o en estadío IV de entre 7 y 57%, exceptuando en el mes de febrero, cuando estas no se hallaron (Figura 1). Contrariamente, solo se hallaron machos completamente maduros (entre 33 y 80%) para los meses de marzo y mayo. Pese a esto, se obtuvieron desoves de ejemplares en todos los meses de estudio, exceptuando las hembras para el mes de febrero. Los machos presentaron una longitud de concha promedio de 35,5 ± 0,8 mm, mientras que para las hembras esta fue de 39,0 ± 0,8 mm, presentándose mayores tallas en las hembras que en los machos (gl =1, F = 8,09, p = 0,0057). Se comprobó la efectividad de todos los métodos aplicados, encontrándose desove en P. arctata, demostrándose que la serotonina a una concentración de 20 µM y el KCL (solo desoves en machos), fueron los métodos con resultados positivos. En cuanto a desoves, El porcentaje promedio de almejas desovadas osciló entre 0 y 16%. Con la inyección de serotonina colocada en el pie a una baja concentración 20 µM, se obtuvo el desove de los dos sexos. Contrariamente, con la inyección de KCl solo desovaron los machos, mientras que no se obtuvieron desoves con los 10 estímulos suministrados al agua (flujo de agua irradiada con UV, cambios de temperatura y salinidad). Mayores porcentajes de animales desovados fueron hallados en los tratados con serotonina a baja concentración en comparación con los demás tratamientos (gl =9, F = 5,71, p < 0,0001). Entre los métodos, el tiempo del inicio de la respuesta de desove luego de suministrar el estímulo de serotonina estuvo entre 22 y 37 minutos, siendo más rápida la respuesta en los machos que en las hembras en los organismos estimulados con serotonina (gl =1, F = 18,43, p = 0,0002). La mortalidad post estimulación de los ejemplares inducidos al desove osciló entre 4 y 51%, siendo mayor cuando se empleó una concentración de serotonina alta, ya sea perforando la concha o sin perforarla, en comparación con la obtenida para los restantes tratamientos (gl = 4, F = 3,83, p = 0,0388). el mejor porcentaje de desove, tiempo de respuesta y sobrevivencia se obtuvo con la serotonina 20 µM. Pregrado Profesional en Acuicultura Pasantías

Introduction: The marine biodiversity is well known in some areas and for some marine ecosystems of the Pacific coast of Costa Rica. The marine sector of Área de Conservación Guanacaste, in the North Pacific of the country, is a priority area for conservation of marine and coastal biodiversity. Objective: Our aim was to increase the knowledge of marine biodiversity in a conservation priority site in Costa Rica and in poorly or scarcely studied marine ecosystems, such as rocky reefs and Sargassum beds, respectively. Methods: The study was conducted in Bahía Salinas and Golfo de Santa Elena in 2013. In January, four rocky reefs were visited; while in February three rocky reefs and one Sargassum bed were visited. We identified the macroinvertebrates and conspicuous fish species through underwater visual census methods (timed swim and band transects). The mean density of each species was estimated through band transects method. Results: A total of 25 invertebrates and 34 fish species were identified. We found a high number of species of invertebrates (23) and fish species (33) in rocky reefs, but few species on Sargassum beds (eight invertebrates and ten fish species). Species composition differed between marine ecosystems. Conclusions: Our study further evidence the limited knowledge of invertebrates and fish communities in these marine ecosystems in the North Pacific of Costa Rica. Considerably more surveys and field work are required to support management decisions that are backed by sound scientific knowledge. Resumen Introducción: La biodiversidad marina es bien conocida en algunas áreas y para algunos ecosistemas marinos de la costa Pacífica de Costa Rica. El sector marino del Área de Conservación Guanacaste, en el Pacífico norte del país, es un área prioritaria para la conservación de la biodiversidad marina y costera. Objetivo: Nuestro objetivo fue el de incrementar el conocimiento de la biodiversidad marina en un sitio prioritario de conservación de Costa Rica y en ecosistemas marinos poco o nulamente estudiados, como son los arrecifes rocosos y mantos de Sargassum, respectivamente. Métodos: El estudio se realizó en Bahía Salinas y Golfo de Santa Elena en el 2013. En enero, cuatro arrecifes rocosos fueron visitados; mientras que en febrero tres arrecifes rocosos y un manto de Sargassum fueron visitados. Identificamos las especies de invertebrados y peces conspicuos a través métodos de censos visuales submarinos (buceos cronometrados y transectos de banda). La densidad promedio de cada especie se estimó mediante el método de transectos de banda. Resultados: Se registró un total de 25 invertebrados y 34 especies de peces. Encontramos un mayor número de especies de invertebrados (23) y peces (33) en los arrecifes rocosos, pero pocas especies en el manto de Sargassum (ocho especies de invertebrados y diez de peces). La composición de especies difirió entre ecosistemas marinos. Conclusiones: Nuestro estudio evidencia el limitado conocimiento de las comunidades de invertebrados y peces en estos ecosistemas marinos en el Pacífico Norte de Costa Rica. Considerablemente más encuestas y trabajo de campo son requeridos para apoyar decisiones de manejo que sean respaldados por conocimientos científicos solidos.

Prevalence, impact on shellfish resources and interspecific, spatial, and temporal variabilities of domoic acid (DA) in bivalves from Galicia (NW Spain) have been studied based on more than 25 years of monitoring data. The maximum prevalence (samples in which DA was detected) (100%) and incidence (samples with DA levels above the regulatory limit) (97.4%) were recorded in Pecten maximus, and the minimum ones in Mytilus galloprovincialis (12.6 and 1.1%, respectively). The maximum DA concentrations were 663.9 mg kg−1 in P. maximus and 316 mg kg−1 in Venerupis corrugata. After excluding scallop P. maximus data, DA was found (prevalence) in 13.3% of bivalve samples, with 1.3% being over the regulatory limit. In general, the prevalence of this toxin decreased towards the North but not the magnitude of its episodes. The seasonal distribution was characterized by two maxima, in spring and autumn, with the later decreasing in intensity towards the north. DA levels decreased slightly over the studied period, although this decreasing trend was not linear. A cyclic pattern was observed in the interannual variability, with cycles of 4 and 11 years. Intoxication and detoxification rates were slower than those expected from laboratory experiments, suggesting the supply of DA during these phases plays an important role.

The objective of this study was to evaluate the possible relaxing effect of essential oils (EOs) (Aloysia triphylla and Lippia alba) and phytochemicals (citral and linalool) in the gastropod Pomacea canaliculata. Animals were exposed to compounds at the concentrations range of 25-750 µL L–1. Magnesium chloride (MgCl2, 10-50 g L–1) and control group (ethanol 6.75 mL L–1, highest concentration used for treatment dilution) were also tested. The EOs, citral and MgCl2 had no relaxing effect at the concentrations range tested, and citral caused aversive behavior (closure of the operculum) from 90 μL L–1. Exposure to linalool at 25, 50, 100, 200 and 400 µL L-1 relaxed 28, 76, 88, 96 and 100% of the animals, respectively. The concentrations of 25, 50 and 400 µL L-1 differed statistically from each other, while 100 and 200 µL L-1 were equal to 50 and 400 µL L-1. All animals recovered up to 40 min, except at of 400 µL L-1. Linalool is effective for relaxing P. canaliculata and can be useful in management techniques that require relaxation. However, further studies are needed to certify whether linalool is appropriate for maintaining animal welfare in invasive procedures that require total insensitivity.

The polyamine putrescine (Put) is a ubiquitous small cationic amine. It plays an essential role in controlling the innate immune response. However, little is known about its function in mollusks. In this study, the Put content was observed to increase in the serum of pearl oyster Pinctada fucata martensii after 6 and 24 h of lipopolysaccharide (LPS) stimulation. Activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) increased, and nitric oxide synthase was downregulated in the Put group (i.e., combined treatment with Put and LPS) compared with that in the LPS group (i.e., combined treatment with phosphate-buffered saline and LPS). Furthermore, activities of alkaline phosphatase and acid phosphatase were inhibited after 6 h of LPS stimulation. The expression levels of the nuclear factor kappa B, IκB kinase, Janus kinase, and signal transducer and activator of transcription proteins genes were all significantly suppressed at 12 and 24 h in the Put group. Pseudomonas aeruginosa and Bacillus subtilis grew better after being incubated with the serum from the Put group than that from the LPS group. Additionally, the Put treatment remarkably inhibited the autophagy of hemocytes mediated by the AMP-activated protein kinase-mammalian target of rapamycin-Beclin-1 pathway. This study demonstrated that Put can effectively inhibit the inflammatory response induced by LPS in pearl oysters. These results provide useful information for further exploration of the immunoregulatory functions of polyamines in bivalves and contribute to the development of immunosuppressive agents.

Tetrahymena rostrata is a free-living ciliated protozoan and is a facultative parasite of some species of terrestrial mollusks. It is a potential biopesticide of pest slugs, such as the grey field slug, which cause considerable damage to crops. T. rostrata has several developmental forms. Homogeneous preparations of the feeding stage cells (trophonts) and excysted stage cells (theronts) were compared for their ability to infect and kill Deroceras reticulatum slugs. Theronts were more effective and remained viable and infective, even after prolonged starvation.

The unique aquatic Pontocaspian (PC) biota of the Black Sea Basin (BSB) is in decline. The lack of detailed knowledge on the status and trends of species, populations, and communities hampers a thorough risk assessment and precludes effective conservation. This paper reviews PC biodiversity trends in the BSB (Bulgaria, Romania, Moldova, Ukraine, and Russia) using endemic mollusks as a model group. We aim to assess changes in PC habitats, community structure, and species distribution over the past century and to identify direct anthropogenic threats. The presence/absence data of target mollusk species were assembled from literature, reports, and personal observations. Pontocaspian biodiversity trends in the northwestern BSB coastal regions were established by comparing 20th‐ and 21st‐century occurrences. The direct drivers of habitat and biodiversity change were identified and documented. We found that a pronounced decline of PC species and communities is driven by (a) damming of rivers, (b) habitat modifications that disturbed previous natural salinity gradients and settings in the studied area, (c) pollution and eutrophication, (d) invasive alien species, and (e) climate change. Four out of the 10 studied regions, namely, the Danube Delta–Razim Lake system, Dniester Liman, Dnieper–Bug estuary, and Taganrog Bay–Don Delta, contain favorable ecological conditions for PC communities and still host threatened endemic PC mollusk species. Distribution data are incomplete, but the scale of deterioration of PC species and communities is evident from the assembled data, as are major direct threats. Pontocaspian biodiversity in the BSB is profoundly affected by human activities. Standardized observation and collection data as well as precise definition of PC biota and habitats are necessary for targeted conservation actions. This study will help to set the research and policy agenda required to improve data collection to accommodate effective conservation of the unique PC biota., Distribution data of unique, endemic Pontocaspian (PC) biodiversity of the Black Sea Basin is incomplete, but the scale of deterioration of PC species and communities is evident from the assembled data, as are major direct threats. This review will help to set the research and policy agenda required to improve data collection to accommodate effective conservation of the unique PC biota.

Mollusks are a prospective food for the world’s growing population, but the contents of toxic and essential trace elements in them have not been studied comprehensively. In this work, using inductively coupled plasma mass spectrometry, the contents of 72 elements in soft tissues of the edible mollusks Mytilus galloprovincialis, Rapana venosa, and Crassostrea gigas from the coastal area of the southwestern Crimea were estimated and compared with the maximum permissible levels. Element accumulation similarities were observed in the two bivalve species. Cluster analysis applied to the non-normalized contents allowed finding an optimal number of non-overlapping element clusters: 1 group of macroelements, 1–2 groups of trace elements, and 1–2 groups of ultratrace elements. As an outcome of this analysis, the element accumulation universality index was introduced, which demonstrated the accumulation universality decrease in the order: mussel &gt, sea snail &gt, oyster. An original approach to estimating the mollusk consumption rate was proposed to assess human health risks. Two possible consumption scenarios were identified for Crimean residents. From the expected consumption of all species in both scenarios, there are no health risks, but they are not excluded, within the 95% probability, from high consumption of mussels and sea snails in the pessimistic scenario.

Tetrahymena rostrata is a free-living ciliated protozoan and is a facultative parasite of some species of terrestrial mollusks. It is a potential biopesticide of pest slugs, such as the grey field slug, which cause considerable damage to crops. T. rostrata has several developmental forms. Homogeneous preparations of the feeding stage cells (trophonts) and excysted stage cells (theronts) were compared for their ability to infect and kill Deroceras reticulatum slugs. Theronts were more effective and remained viable and infective, even after prolonged starvation.