Search

Deep-sea hydrothermal vents are characterized by high hydrostatic pressure, hypoxia, darkness and toxic substances. However, how organisms adapt to such extreme marine ecosystems remain poorly understood. We hypothesize that adaptive evolution plays an essential role in generating novelty for evolutionary adaptation to the deep-sea environment because adaptive evolution has been found to be critical for species origin and evolution. In this project, the chromosome-level genome of the deep-sea hydrothermal vent gastropod T. jamsteci was constructed for the first time to examine molecular mechanisms of its adaptation to the deep-sea environment. The genome size was large (2.54 Gb), ranking at the top of all species in the Vetigastropoda subclass, driven primarily by the bursts of transposable elements (TEs). The transposition of TEs may also trigger chromosomal changes including both inter-chromosomal fusions and intra-chromosomal activities involving chromosome inversions, rearrangements and fusions, as revealed by comparing the genomes of T. jamsteci and its closely related shallow-sea species Gibbula magus. Innovative changes including the expansion of the ABC transporter gene family that may facilitate detoxification, duplication of genes related to endocytosis, immunity, apoptosis, and anti-apoptotic domains that may help T. jamsteci fight against microbial pathogens, were identified. Furthermore, comparative analysis identified positive selection signals in a large number of genes including the hypoxia up-regulated protein 1, which is a chaperone that may promote adaptation of the T. jamsteci to hypoxic deepsea environments, hox2, Rx2, Pax6 and cilia-related genes BBS1, BBS2, BBS9 and RFX4. Notably, because of the critical importance of cilia and IFT in development, positive selection in cilia-related genes may play a critical role in facilitating T. jamsteci to adapt to the high-pressure deep-sea ecosystem. Results from this study thus revealed important molecular clues that may facilitate further research on the adaptation of molluscs to deep-sea hydrothermal vents., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

The widespread and severe drop in dissolved oxygen concentration in the open ocean and coastal waters has attracted much attention, but assessments of the impacts of environmental hypoxia on aquatic organisms have focused primarily on responses to current exposure. Past stress exposure might also affect the performance of aquatic organisms through carryover effects, and whether these effects scale from positive to negative based on exposure degree is unknown. We investigated the carryover effects of varying embryonic hypoxia levels (mediate hypoxia: 3.0-3.1 mg O 2 /L; severe hypoxia: 2.0-2.1 mg O 2 /L) on the fitness traits of adult Pacific abalone (Haliotis discus hannai), including growth, hypoxia tolerance, oxygen consumption, ammonia excretion rate, and biochemical responses to acute hypoxia. Moderate embryonic hypoxia exposure significantly improved the hypoxia tolerance of adult Pacific abalone without sacrificing growth and survival. Adult abalone exposed to embryonic hypoxia exhibited physiological plasticity, including decreased oxygen consumption rates under environmental stress, increased basal methylation levels, and a more active response to acute hypoxia, which might support their higher hypoxia tolerance. Thus, moderate oxygen declines in early life have persistent effects on the fitness of abalone even two years later, further affecting population dynamics. The results suggested that incorporating the carryover effects of embryonic hypoxia exposure into genetic breeding programs would be an important step toward rapidly improving the hypoxia tolerance of aquatic animals. The study also inspires the protection of endangered wild animals and other vulnerable species under global climate change., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Due to their distinctive anatomical characteristics, land slugs are appealing research subjects from a variety of angles, including stem cell biology, regeneration, embryonic development, allometry, and neurophysiology. Here we present SlugAtlas, an anatomical and histological online resource of the land slugs Deroceras laeve and Ambigolimax valentianus. The atlas is composed of series of histological sections on the horizontal, sagittal, and transversal planes for both species with 3D viewing tools of their major organs. The atlas was used in this work for a comparative analysis of the major organs and tissues of these two species. We provide a comprehensive histological description of them and an explanation of novel findings of unique features of their anatomy. For D. laeve, we additionally studied its ability for degrowth and regrowth, a feature that characterizes animals with high regeneration potential and obtained initial results on the study of the regeneration of its tail. SlugAtlas is a resource that is also built to accommodate future growth and, along with the experimental techniques that we have developed, will provide the foundation for research projects in a variety of biological domains., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2024 Lozano-Flores et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

The influx of volcanic ash into seawater alters particle composition with implications for the cellular, physiological and anatomical response of suspension-feeding organisms. Adult females of Crepipatella peruviana were exposed to three diets consisting of a fixed concentration of 50,000 cells ml -1 of the microalga Isochrysis galbana plus different concentrations of ash particles (30, 90 and 150 mg L -1 ). The objective was to determine the cellular, physiological and anatomical responses. Mortality increased with ash concentrations, while feeding and respiration rates, tissue weight, and condition index decreased. The gills showed severe degradation of cilia and the presence of large mucous aggregates of cilia and ash. An increase in ash resulted in decreased lipid peroxidation and protein carbonyls, but increased total antioxidant capacity and phenols. Thus, volcanic ash particles may exert a high impact at both cellular and physiological levels for C. peruviana, where inhibition of gill function reduces the ability to acquire food., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Predator-prey interactions are important in shaping ecosystem structure. Consequently, impacts of accelerating global warming on predators will have notable implications. Effects are likely to be particularly marked for tropical organisms which are anticipated to be sensitive to further thermal stress. Here, we investigated effects of future ocean warming on the predatory dogwhelk Reishia clavigera and its predation of Saccostrea cucullata. Mortality of the predators rapidly increased under the extreme elevated temperature, while those exposed to moderate elevated temperature displayed similar mortality as the ambient. Predators that survived moderate temperature increases altered their oxygen consumption patterns, increased average feeding rates, and functional responses, although condition index and energy reserves were unchanged. Overall, we show extreme ocean warming scenarios can remove predators and their consumption of prey from an ecosystem, whereas moderate warming can intensify predator-prey interactions. Such temperature-dependent alterations to predator-prey interactions would lead to fundamental changes of ecosystem structure as the ocean warms., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Limpets are a key taxon regulating the benthic community structure and serving as prey for various predators in rocky shores, however, their role in food web dynamics is still unclear. To determine environmental factors influencing the limpet diet, carbon and nitrogen stable isotopes in limpets and food sources were analyzed on three different coastal habitats. Sediment organic matter contributed the most (86 %) to the limpet diet in bedrocks around tidal flats with abundant sediment supply from the terrestrial matter inflow and the sediment resuspension. Microphytobenthos and macroalgae were the main food sources (57 % and 20 %, respectively) for the limpets around beaches, where benthic flora was abundant. Limpets in bedrocks, erosional habitat, primarily consumed relatively abundant phytoplankton (33 %) and microphytobenthos (28 %). Contrary to previous studies, habitat type, rather than latitude or seawater characteristics, was the most important factor determining the limpet diet. This result also suggests that limpets are non-selective scraper that consume abundant food sources., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The seascape comprises multiple environmental variables that interact with species biology to determine patterns of spatial genetic variation. The environment imposes spatially variable selective forces together with homogenizing and diverging drivers that facilitate or restrict dispersal, which is a complex, time-dependent process. Understanding how the seascape influences spatial patterns of genetic variation remains elusive, particularly in coastal upwelling systems. Here, we combine genome-wide SNP data, Lagrangian larval dispersal simulated over a hydrodynamic model, and ocean environmental information to quantify the relative contribution of ocean circulation and environmental heterogeneity as drivers of the spatial genetic structure of two congeneric intertidal limpets, Scurria scurra and S. araucana, along the central coast of Chile. We find that a genetic break observed in both limpet species coincides with a break in connectivity shown by the Lagrangian dispersal, suggesting that mean ocean circulation is an important seascape feature, in particular for S. scurra. For S. araucana, environmental variation appears as a better predictor of genetic structure than ocean circulation. Overall, our study shows broad patterns of seascape forcing on genetic diversity and contributes to our understanding of the complex ecological and evolutionary interactions along coastal upwelling systems., (© 2024. The Author(s).)

A central question in ecology is to what extent do trophic interactions govern the structure and function of communities? This question is becoming more pressing as trophic interactions shift with rapid climate change. Sea urchins and abalone are key invertebrates in the habitats where they reside. Sea urchins are critical members of exemplar trophic cascades in kelp forests due to their impact on kelp establishment and maintenance; yet their populations are controlled by predators, such as sea otters and sunflower sea stars. Abalone compete with urchins for macroalgal food resources and therefore can help regulate urchin populations in kelp forests. Given that both urchin tests and abalone shells used for predator defense are comprised of calcium carbonate, much research has been conducted on the impacts of ocean acidification (OA) on these calcified structures. A growing body of literature has shown that urchin tests are less calcified and break with less force under OA conditions. Less is known about abalone, but their shells also appear to respond negatively to OA. Using kelp forest communities as exemplar ecosystems, we discuss the morphological, biomechanical, and physiological responses to OA in urchins and abalone and consider how these individual level responses scale to trophic interactions and ultimately whole ecosystem processes. Although the impacts of OA on the calcified structures used for defense have been well studied, calcified mechanisms for food consumption, such as the Aristotle's lantern of urchins, are much less understood. Thus, examining both the feeding and defense sides of trophic interactions would greatly improve our understanding of OA responses across individual to ecosystem scales. More generally, measurements of morphological, biomechanical, and physiological responses to OA can be made in individuals to help predict higher level ecological responses, which would greatly contribute to broader predictions of whole ecosystem responses to OA., (© The Author(s) 2024. Published by Oxford University Press on behalf of the Society for Integrative and Comparative Biology.)

Marine heatwaves have caused massive mortality in coastal benthic ecosystems, altering community composition. Here, we aim to understand the effects of single and sequential sublethal heatwaves in a temperate benthic ecosystem, investigating their disturbance on various levels of ecological hierarchy, i.e. individual physiology, trophic groups' biomass and ecosystem carbon fluxes. To do so, we performed a near-natural experiment using outdoor benthic mesocosms along spring/summer, where communities were exposed to different thermal regimes: without heatwaves (0HW), with one heatwave (1HW) and with three heatwaves (3HWs). Gastropods were negatively impacted by one single heatwave treatment, but the exposure to three sequential heatwaves caused no response, indicating ecological stress memory. The magnitude of ecosystem carbon fluxes mostly decreased after 1HW, with a marked negative impact on mesograzers' feeding, while the overall intensity of carbon fluxes increased after 3HWs. Consumers' acclimation after the exposure to sequential heatwaves increased grazing activity, representing a threat for the macroalgae biomass. The evaluation of physiological responses and ecological interactions is crucial to interpret variations in community composition and to detect early signs of stress. Our results reveal the spread of heatwave effects along the ecological hierarchical levels, helping to predict the trajectories of ecosystem development.This article is part of the theme issue 'Connected interactions: enriching food web research by spatial and social interactions'.

Long-term baseline data that allow tracking how predator-prey interactions have responded to intensifying human impacts are often lacking. Here, we assess temporal changes in benthic community composition and interactions between drilling predatory gastropods and their molluscan prey using the Holocene fossil record of the shallow northern Adriatic Sea, which is characterized by a long history of human transformation. Molluscan assemblages differ between the Isonzo and Po prodelta, but both show consistent temporal trends in the abundance of dominant species. Samples of mollusc prey collected at high stratigraphic resolution indicate that drilling frequencies have drastically declined in the Po prodelta since the mid-twentieth century, while a weaker trend in the more condensed sediments of the Isonzo prodelta is not statistically significant. The decrease in drilling predation intensity and the community turnover are linked to the loss of predatory gastropods and the increased relative abundance of less-preferred prey during the most recent decades. Our results align with data showing the substantial depletion of marine resources at higher trophic levels in the region and indicate that the strong simplification of the food web initiated in the late nineteenth century accelerated further since the mid-twentieth century.

Nudibranchs, with their mesmerizing diversity and ecological significance, play crucial roles in marine ecosystems. Central to their feeding prowess is the radula, a chitinous structure with diverse morphologies adapted to prey preferences and feeding strategies. This study focuses on elucidating wear coping mechanisms in radular teeth of carnivorous molluscs, employing Dendronotus lacteus (Dendronotidae) and Flabellina affinis (Flabellinidae) as model species. Both species forage on hydrozoans. Through scanning electron microscopy, confocal laser scanning microscopy, nanoindentation, and energy-dispersive X-ray spectroscopy, the biomechanical and compositional properties of their teeth were analyzed. Notably, tooth coatings, composed of calcium (Ca) or silicon (Si) and high hardness and stiffness compared to the internal tooth structure, with varying mineral contents across tooth regions and ontogenetic zones, were found. The presence of the hard and stiff tooth coatings highlight their role in enhancing wear resistance. The heterogeneities in the autofluorescence patterns related to the distribution of Ca and Si of the coatings. Overall, this study provides into the biomechanical adaptations of nudibranch radular teeth, shedding light on the intricate interplay between tooth structure, elemental composition, and ecological function in marine molluscs., (© 2024 The Author(s). Journal of Morphology published by Wiley Periodicals LLC.)

Rocky shore communities are shaped by complex interactions among environmental drivers and a range of biological processes. Here, we investigated the importance of abiotic and biotic drivers on the population structure of key rocky intertidal species at 62 sites, spanning ∼50% of the Brazilian rocky shoreline (i.e., ∼500 km). Large-scale population patterns were generally explained by differences in ocean temperature and wave exposure. For the gastropod species Lottia subrugosa, differences at smaller scales (i.e., 0.1-1 km) were better explained by other abiotic influences such as freshwater discharge and substrate roughness. Based on the general population patterns of intertidal species identified, three main oceanographic groups were observed: a cold-oligotrophic grouping at northern sites (Lakes sub-region), a eutrophic group associated with large estuaries and urban zones (Santos and Guanabara bays); and a transitional warm-water group found between the two more productive areas. Larger individuals of Stramonita brasiliensis, L. subrugosa and Echinolittorina lineolata were generally found in the cold-oligotrophic system (i.e., upwelling region), while small suspension feeders dominate the warm-eutrophic systems. Evidence of bottom-up regulation was not observed, and top-down regulation effects were only observed between the whelk S. brasiliensis and its mussel prey Pernaperna. Environmental drivers as compared to biotic interactions, therefore, play a key role determining the population structure of multiple intertidal species, across a range of spatial scales along the SW Atlantic shores., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Marine animals are challenged by chronically raised temperatures alongside an increased frequency of discrete, severe warming events. Exposure to repeated heat shocks could result in heat hardening, where sub-lethal exposure to thermal stress temporarily enhances thermotolerance, and may be an important mechanism by which marine species will cope with future thermal challenges. However, we have relatively little understanding of the effects of heat hardening in comparison to chronic exposure to elevated temperatures. Therefore, we compared the effects of heat hardening from repeated exposure to acute heat shocks and chronic exposure to elevated temperatures on thermal tolerance in the European abalone, Haliotis tuberculata. Adult abalones were exposed to either control temperature (15 °C), chronic warming (20 °C) or a regime of two events of repeated acute heat shock cycles (23-25 °C) during six months, and their thermal tolerance and performance, based upon cardiac activity, compared using a dynamic ramping assay. The cost associated with each treatment was also estimated via measurements of condition index (CI). Abalone exposed to both temperature treatments had higher upper thermal limits than the control, but heat-hardened individuals had significantly higher CI values, indicating an enhancement in condition status. Differences in the shape of the thermal performance curve suggest different mechanisms may be at play under different temperature exposure treatments. We conclude that heat hardening can boost thermal tolerance in this species, without performance trade-offs associated with chronic warming., Competing Interests: Declaration of competing interest none., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

Neuropeptides play essential roles in coordinating reproduction. Egg-laying hormone (ELH) is conserved in genetic sequence and behavioral function across molluscs, where neuronal clusters secrete ELH to modulate and induce egg-laying. Here we investigated ELH in the nudibranch mollusc, Berghia stephanieae. ELH preprohormone gene orthologs, which showed clade-specific differences at the C-terminus of the predicted bioactive peptide, were identified in brain transcriptomes across several nudipleuran species, including B. stephanieae. ELH shares deep homology with the corticotropin-releasing hormone gene family, which has roles broadly in stress response. Injection of synthesized B. stephanieae ELH peptide into mature individuals induced egg-laying. ELH gene expression in the brain and body was mapped using in-situ hybridization chain reaction. Across the adult brain, 300-400 neurons expressed ELH. Twenty-one different cell types were identified in adults, three of which were located unilaterally on the right side, which corresponds to the location of the reproductive organs. Ten cell types were present in pre-reproductive juvenile stages. An asymmetric cluster of approximately 100 small neurons appeared in the right pedal ganglion of late-stage juveniles. Additional neurons in the pleural and pedal ganglia expressed ELH only in adults that were actively laying eggs and sub-adults that were on the verge of doing so, implicating their direct role in reproduction. Outside the brain, ELH was expressed on sensory appendages, including in presumptive sensory neurons. Its widespread expression in the nudibranch B. stephanieae suggests that ELH plays a role beyond reproduction in gastropod molluscs., Competing Interests: Declaration of competing interest The authors declare no competing interests., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

The selective factors that shape phenotypic diversity in prey communities with aposematic animals are diverse and coincide with similar diversity in the strength of underlying secondary defences. However, quantitative assessments of colour pattern variation and the strength of chemical defences in assemblages of aposematic species are lacking. We quantified colour pattern diversity using quantitative colour pattern analysis (QCPA) in 13 dorid nudibranch species (Infraorder: Doridoidei) that varied in the strength of their chemical defences. We accounted for the physiological properties of a potential predator's visual system (a triggerfish, Rhinecanthus aculeatus ) and modelled the appearance of nudibranchs from multiple viewing distances (2 and 10 cm). We identified distinct colour pattern properties associated with the presence and strength of chemical defences. Specifically, increases in chemical defences indicated increases in colour pattern boldness (i.e. visual contrast elicited via either or potentially coinciding chromatic, achromatic and/or spatial contrast). Colour patterns were also less variable among species with chemical defences when compared to undefended species. Our results indicate correlations between secondary defences and diverse, bold colouration while showing that chemical defences coincide with decreased colour pattern variability among species. Our study suggests that complex spatiochromatic properties of colour patterns perceived by potential predators can be used to make inferences on the presence and strength of chemical defences.

The Miocene Climate Optimum (MCO, ~ 17-14 Ma) was a time of extraordinary marine biodiversity in the Circum-Mediterranean Region. This boom is best recorded in the deposits of the vanished Central Paratethys Sea, which covered large parts of central to southeastern Europe. This sea harbored an extraordinary tropical to subtropical biotic diversity. Here, we present a georeferenced dataset of 859 gastropod species and discuss geodynamics and climate as the main drivers to explain the changes in diversity. The tectonic reorganization around the Early/Middle Miocene boundary resulted in the formation of an archipelago-like landscape and favorable conditions of the MCO allowed the establishment of coral reefs. Both factors increased habitat heterogeneity, which boosted species richness. The subsequent cooling during the Middle Miocene Climate Transition (~ 14-13 Ma) caused a drastic decline in biodiversity of about 67%. Among the most severely hit groups were corallivorous gastropods, reflecting the loss of coral reefs. Deep-water faunas experienced a loss by 57% of the species due to changing patterns in circulation. The low sea level led to a biogeographic fragmentation reflected in higher turnover rates. The largest turnover occurred with the onset of the Sarmatian when bottom water dysoxia eradicated the deep-water fauna whilst surface waters-dwelling planktotrophic species underwent a crisis., (© 2024. The Author(s).)

Myoinhibitory peptides (MIPs) affect various physiological functions, including juvenile hormone signaling, muscle contraction, larval development, and reproduction in invertebrates. Although MIPs are ligands for MIP and/or sex peptide receptors (MIP/SPRs) in diverse arthropods and model organisms belonging to Lophotrochozoa, the MIP signaling system has not yet been fully investigated in mollusks. In this study, we identified the MIP signaling system in the Pacific abalone Haliotis discus hannai (Hdh). Similar to the invertebrate MIPs, a total of eight paracopies of MIPs (named Hdh-MIP1 to Hdh-MIP8), harboring a WX 5-7 Wamide motif, except for Hdh-MIP2, were found in the Hdh-MIP precursor. Furthermore, we characterized a functional Hdh-MIPR, which responded to the Hdh-MIPs, except for Hdh-MIP2, possibly linked with the PKC/Ca 2+ and PKA/cAMP signaling pathways. Hdh-MIPs delayed larval metamorphosis but increased the spawning behavior. These results suggest that the Hdh-MIP signaling system provides insights into the unique function of MIP in invertebrates., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Observations from the California Current System (CalCS) indicate that the long-term trend in ocean acidification (OA) and the naturally occurring corrosive conditions for the CaCO 3 mineral aragonite (saturation state Ω < 1) have a damaging effect on shelled pteropods, a keystone group of calcifying organisms in the CalCS. Concern is heightened by recent findings suggesting that shell formation and developmental progress are already impacted when Ω falls below 1.5. Here, we quantify the impact of low Ω conditions on pteropods using an individual-based model (IBM) with life-stage-specific mortality, growth, and behavior in a high-resolution regional hindcast simulation of the CalCS between 1984 and 2019. Special attention is paid to attributing this impact to different processes that lead to such low Ω conditions, namely natural variability, long-term trend, and extreme events. We find that much of the observed damage in the CalCS, and specifically >70% of the shell CaCO 3 loss, is due to the pteropods' exposure to naturally occurring low Ω conditions as a result of their diel vertical migration (DVM). Over the hindcast period, their exposure to damaging waters (Ω < 1.5) increases from 9% to 49%, doubling their shell CaCO 3 loss, and increasing their mortality by ~40%. Most of this increased exposure is due to the shoaling of low Ω waters driven by the long-term trend in OA. Extreme OA events amplify this increase by ~40%. Our approach can quantify the health of pteropod populations under shifting environmental conditions, and attribute changes in fitness or population structure to changes in the stressor landscape across hierarchical time scales., (© 2024 The Author(s). Global Change Biology published by John Wiley & Sons Ltd.)

Few studies have considered the capabilities of gastropods living in minerally-deficient acidified coastal waters to compensate for outer shell corrosion or compromised growing edge shell production. We compared inner shell thickening between pristine shells (control) and corroded shells (experiment) of two related intertidal neritid gastropod species from reduced salinity and acidified environments. We predicted that the rocky-shore, Nerita chamaeleon, which has greater access to shell building biomineralization substrates, should better control shell thickness than the estuarine, Neripteron violaceum. Accordingly, N. chameleon was found to compensate perfectly for variation in the thickness of the outer calcitic blocky layer (BL). Optimal shell thickness (OST) was maintained by selective reabsorption of the aperture ridge of the distal shell (aragonitic crossed-lamellar layer, CL) and by increased internal deposition of proximal (older) shell (aragonitic protocrossed lamellar, PCL). Despite greater exposure to acidification and hyposalinity, N. violaceum showed no significant compensatory shell thickening. These findings reveal that shell thickening capability may vary greatly among intertidal gastropods and that this may be constrained by environmental biomineralization substrate availability. Such environmentally-related responses carry implications for predicted future reductions in coastal water pH and salinity., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Transcriptome sequencing has offered immense opportunities to study non-model organisms. Abalone is an important marine mollusk that encounters harsh environmental conditions in its natural habitat and under aquaculture conditions; hence, research that increases molecular information to understand abalone physiology and stress response is noteworthy. Accordingly, the study used transcriptome sequencing of the gill tissues of abalone exposed to low salinity stress. The aim is to explore some enriched pathways during salinity stress and the crosstalk and functions of the genes involved in the candidate biological processes for future further analysis of their expression patterns. The data suggest that abalone genes such as YAP/TAZ, Myc, Nkd, and Axin (involved in the Hippo signaling pathway) and PI3K/Akt, SHC, and RTK (involved in the Ras signaling pathways) might mediate growth and development. Thus, deregulation of the Hippo and Ras pathways by salinity stress could be a possible mechanism by which unfavorable salinities influence growth in abalone. Furthermore, PEPCK, GYS, and PLC genes (mediating the Glucagon signaling pathway) might be necessary for glucose homeostasis, reproduction, and abalone meat sensory qualities; hence, a need to investigate how they might be influenced by environmental stress. Genes such as MYD88, IRAK1/4, JNK, AP-1, and TRAF6 (mediating the MAPK signaling pathway) could be useful in understanding abalone's innate immune response to environmental stresses. Finally, the aminoacyl-tRNA biosynthesis pathway hints at the mechanism by which new raw materials for protein biosynthesis are mobilized for physiological processes and how abalone might respond to this process during salinity stress. Low salinity clearly regulated genes in these pathways in a time-dependent manner, as hinted by the heat maps. In the future, qRT-PCR verification and in-depth study of the various genes and proteins discussed would provide enormous molecular information resources for the abalone biology., Competing Interests: Declaration of competing interest The authors declare that they have no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Understanding the underlying reasons for phenotypic plasticity and resulting morphological disparity is one of the key topics of evolutionary research. The phenotypic plasticity of extant and fossil melanopsids has been widely documented. Yet millennial-resolution, well-dated records from small aquatic habitats harboring endemics are scarce. The thermal spring-fed Lake Pețea is an ice age refugia harboring a unique endemic warm-water fauna. Subfossil melanopsids display incredible morphological variability from smooth to keeled, elongated to ribbed, shouldered forms. Numerous morphotypes have been considered as individual taxa with a fluent succession from the smooth elongated to the ribbed, shouldered types. This study presents an extensive morphometric analysis of subfossil melanopsids (ca. 3500 specimens) derived from stratified samples with an independent chronology. The aim was to separate morphotypes for investigations of temporal morphological disparity. Our results challenge the widely accepted hypothesis that proposes the evolution of shouldered, compressed, ribbed shells through a two-step process from smooth elongated spindle-shaped shells. Instead, it suggests that the subfossil shells belong to two distinct taxa present throughout the available stratigraphic data. The main components of shape variation, shape globularity, and shell coiling seem allometry-related. Ribs, striation, and keels appear randomly. High-spired spindle-shaped forms were considered to represent specimens of Microcolpia daudebartii hazayi. Bulkier low-spired and shouldered specimens represent phenotypes of Mi. parreyssii parreyssii. The collective and random distribution of morphotypes from the early stages of the lake's history also refutes the idea of a continuous transformation of the elongated forms into compressed, shouldered ones. Rather points to multiple events and environmental stimuli triggering development. Melanopsids appear in Late Glacial horizons, with Theodoxus prevostianus preferring temperatures above 23°C which may indicate the subordinate presence of hot water microhabitats in cooler waters., (© 2024 Wiley Periodicals LLC.)

Photosynthetic animals produce oxygen, providing an ideal lens for studying how oxygen dynamics influence thermal sensitivity. The algivorous sea slug Elysia viridis can steal and retain chloroplasts from the marine alga Bryopsis sp. for months when starved, but chloroplast retention is mere weeks when they are fed another green alga, Chaetomorpha sp. To examine plasticity in thermal tolerance and changes in net oxygen exchange when fed and starving, slugs fed each alga were acclimated to 17°C (the current maximum temperature to which they are exposed in nature) and 22°C (the increase predicted for 2100) and measured at different points during starvation. We also examined increased illumination to evaluate a potential tradeoff between increased oxygen production but faster chloroplast degradation. Following acclimation, we subjected slugs to acute thermal stress to determine their thermal tolerance. We also measured net oxygen exchange before and after acute thermal stress. Thermal tolerance improved in slugs acclimated to 22°C, indicating they can acclimate to temperatures higher than they naturally experience. All slugs exhibited net oxygen uptake, and rates were highest in recently fed slugs before exposure to acute thermal stress. Oxygen uptake was suppressed following acute thermal stress. Under brighter light, slugs exhibited improved thermal tolerance, possibly because photosynthetic oxygen production alleviated oxygen limitation. Accordingly, this advantage disappeared later in starvation when photosynthesis ceased. Thus, E. viridis can cope with heatwaves by suppressing metabolism and plastically adjusting heat tolerance; however, starvation influences a slug's thermal tolerance and oxygen uptake such that continuous access to algal food for its potential nutritive and oxygenic benefits is critical when facing thermal stress., Competing Interests: Competing interests The authors declare no competing or financial interests., (© 2024. Published by The Company of Biologists Ltd.)

Ocean acidification (OA), which reduces ocean pH and leads to substantial changes in seawater carbonate chemistry, may strongly impact organisms, especially those with carbonate skeletons. In marine molluscs, while the physiological effects of OA are well known, with a reduction of growth and shell calcification, there are few studies on behavioural effects. A large marine gastropod, Haliotis tuberculata, was exposed to ambient (pH T 8.0) or low pH (pH T 7.7) during a 5-month experiment. Because animal fitness can be affected through various behavioural changes, a broad spectrum of behavioural parameters was investigated, including situations involving no stress, responses to predators, righting to evaluate indirectly the level of energy reserves, and finally, reproductive behaviour. In addition, we measured the expression profile of the GABA A-like and serotonin receptor genes, often described as central neuromodulators of sensory performance and behaviour and known to be affected by OA in molluscs. No significant effect of low pH as compared to ambient pH was observed on abalone behaviour for any of these behavioural traits or gene expressions after either one week or several months of exposure to OA. The significance tests were corroborated by estimating the size of pH effects. The behaviour of this mollusc appears not to be affected by pH decrease expected by the end of the century, suggesting some resilience of the species to OA at the adult stage. This is probably related to the ecological niche of this abalone, where important pH variations can be observed at tidal, diurnal or seasonal scales., Competing Interests: Declaration of competing interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: Stephanie Bordenave reports financial support was provided by Foundation for Research on Biodiversity. Stephanie Bordenave reports financial support was provided by Ministère de la Transition Ecologique et Solidaire (MTES), France. Sabine Roussel reports financial support was provided by French LabexMER program (OASYS project)., (Copyright © 2023. Published by Elsevier B.V.)

Understanding the mechanisms by which individual organisms respond and populations adapt to global climate change is a critical challenge. The role of plasticity and acclimation, within and across generations, may be essential given the pace of change. We investigated plasticity across generations and life stages in response to ocean acidification (OA), which poses a growing threat to both wild populations and the sustainable aquaculture of shellfish. Most studies of OA on shellfish focus on acute effects, and less is known regarding the longer term carryover effects that may manifest within or across generations. We assessed these longer term effects in red abalone (Haliotis rufescens) using a multi-generational split-brood experiment. We spawned adults raised in ambient conditions to create offspring that we then exposed to high pCO 2 (1180 μatm; simulating OA) or low pCO 2 (450 μatm; control or ambient conditions) during the first 3 months of life. We then allowed these animals to reach maturity in ambient common garden conditions for 4 years before returning the adults into high or low pCO 2 treatments for 11 months and measuring growth and reproductive potential. Early-life exposure to OA in the F1 generation decreased adult growth rate even after 5 years especially when abalone were re-exposed to OA as adults. Adult but not early-life exposure to OA negatively impacted fecundity. We then exposed the F2 offspring to high or low pCO 2 treatments for the first 3 months of life in a fully factorial, split-brood design. We found negative transgenerational effects of parental OA exposure on survival and growth of F2 offspring, in addition to significant direct effects of OA on F2 survival. These results show that the negative impacts of OA can last within and across generations, but that buffering against OA conditions at critical life-history windows can mitigate these effects., (© 2023 John Wiley & Sons Ltd.)

Ocean acidification poses a significant threat to calcifying invertebrates by negatively influencing shell deposition and growth. An organism's performance under ocean acidification is not determined by the susceptibility of one single life-history stage, nor is it solely controlled by the direct physical consequences of ocean acidification. Shell development by one life-history stage is sometimes a function of the pH or p CO2 levels experienced during earlier developmental stages. Furthermore, environmental factors such as access to nutrition can buffer organismal responses of calcifying invertebrates to ocean acidification, or they can function as a co-occurring stressor when access is low. We reared larvae and juveniles of the planktotrophic marine gastropod Crepidula fornicata through combined treatments of nutritional stress and low pH, and we monitored how multiple stressors endured during the larval stage affected juvenile performance. Shell growth responded non-linearly to decreasing pH, significantly declining between pH 7.6 and pH 7.5 in larvae and juveniles. Larval rearing at pH 7.5 reduced juvenile growth as a carryover effect. Larval rearing at pH 7.6 reduced subsequent juvenile growth despite the absence of a negative impact on larval growth, demonstrating a latent effect. Low larval pH magnified the impact of larval nutritional stress on competence for metamorphosis and increased carryover effects of larval nutrition on juvenile growth. Trans-life-cycle effects of larval nutrition were thus modulated by larval exposure to ocean acidification. [ABSTRACT FROM AUTHOR]

Two new species of calliotropid gastropods, Calliotropis (Riselloidea) faustiankensis sp. nov. and Calliotropis (Riselloidea) lukovensis sp. nov., are described from the Middle Jurassic (Middle Bathonian−Upper Callovian) of Poland. Additionally, new excellently preserved shells of Calliotropis (Riselloidea) biarmata (Münster) allow redefinition of this species. The new morphological information obtained from these three fossil species of Calliotropis in combination with the dataset assembled from 20 extinct and 24 living calliotropids is here summarized in quantitative multivariate and principal component analyses suggesting an onshore-offshore trend in calliotropid gastropod evolution from the Triassic to Recent times. This trend, which is expressed in the morphology of shells, shows that the Mesozoic species are mostly shallow water, while Cenozoic and Recent taxa are mostly deep water. The distinction supports earlier suggestions that the genus Calliotropis can be subdivided into two temporal subgenera belonging to the family Eucyclidae Koken. http://zoobank.org/urn:lsid:zoobank.org:pub:C8362FB8-966A-4322-95D5-7151CED20476 [ABSTRACT FROM AUTHOR]

Abstract Abalones are especially susceptible to environmental lighting conditions. This factor greatly affects crucial biological process such as feeding rates, energy balance, physiological stress status, and consequently, growth and survival of farmed abalone. Most of these effects have been studied in the economically valuable abalone Haliotis discus hannai. The use of specific photoperiods, and/or light qualities and intensities, have been proposed as managing strategies to increase its production; however, for extensive off-shore or in intensive land-based farming systems, lighting conditions are not likely to be easily managed. Despite the great importance of the biological responses to the light/dark stimuli for abalone farming production, to the best of our knowledge the genetic control upon the variation associated behavioral traits have not been studied. Therefore, the aim of this study was to estimate the heritable variation and potential responses to selection for the phototaxis [i.e., displacement towards (positive) or against (negative) the light source] and locomotion behaviors associated to the intensity of the response (i.e., crawling speed and displacement distance) to the light/dark stimuli in juvenile H. discus hannai. Genetic and phenotypic correlations between these traits were also estimated. Results showed moderate but significant heritable variations for phototaxis (h 2 = 0.15) and locomotion responses (h 2 = 0.18–0.37); and significant positive genetic correlations among them. Expected gain responses to selection per generation (with a selection intensity of 2.06, i.e., selecting 5% of the individuals from a population) were moderate for phototaxis variation (16%) and high for locomotion responses variation (33–67 or 36–73%, depending on the model used for the estimations). As a consequence, the potential for reducing (or incrementing, depending on the breeding goal) the reactivity or the sensibility to the light stimulus by selective breeding is good, and can be an attractive way of indirectly improving growth, survival and general welfare of farmed H. discus hannai. Highlights • First estimations of heritability and potential response to selection for the reactivity to lighting conditions in mollusks. • Phototaxis variation is heritable and with moderate potential response to selection in juvenile H. discus hannai. • Variation in locomotion responses to light/dark stimuli are heritable and with high potential response to selection. • A genetic breeding program for reactivity to lighting conditions can be implemented for improving H. discus hannai farming. [ABSTRACT FROM AUTHOR]

Variation in snail shell shape has provided evolutionary biologists with excellent material for the study of local adaptation to local environments. However, the assumption that shell shape variation is evidence of distinct lineages (species) might have led to taxonomic inflation within some gastropod lineages. Here, we compare shell shape variation and genetic structure of two independent lineages of New Zealand rocky shore whelks in order to understand the process that leads to an unusual disjunct distribution. We examined the Buccinulum vittatum complex (three subspecies plus Buccinulum colensoi) using mitochondrial DNA sequences, 849 single nucleotide polymorphisms and geometric morphometric data on shell shape. Specimens within the range of B. colensoi shared nuclear markers and mitochondrial DNA haplotypes with the southern subspecies Buccinulum vittatum littorinoides, whereas the northern samples (Buccinulum vittatum vittatum) had distinct genotypes. We infer that gene flow between B. colensoi and B. v. littorinoides is greater than between either of these taxa and B. v. vittatum. The distinctive shell sculpturing of B. colensoi is maintained despite gene flow, suggesting a role for selection. Although the shell form of B. colensoi appears to be an adaptation to local conditions, we did not observe convergent evolution in the sympatric whelk species Cominella maculosa. [ABSTRACT FROM AUTHOR]

A 45-day trial was conducted to study the effect of seawater total alkalinity (TA) level up- and downregulation on the growth performance and calcification of Haliotis discus hannai Ino, while seawater pH was maintained at pH NBS  = 8.1. Although seawater was not acidified, the results showed that TA downregulation caused a significant reduction (P < 0.05) in the somatic tissue growth of juvenile abalone, while TA upregulation significantly increased growth performance (P < 0.05). Similar to the impacts of pH reduction, TA downregulation also induces a decline in CO 2 buffering capacity, which may be the reason why somatic tissue growth was reduced, as lowered CO 2 buffering capacity was reported to shift the acid-base balancing of abalone. Parts of the periostracum layer weremissing and exposed the inner shell layers of the individuals from the TA-downregulated group. Scanning electron microscopy (SEM) results showed calcium carbonate densely deposited onto the inner shell in the control and TA-upregulated groups, while sparsely deposited calcium carbonate was observed in the TA-downregulated group. The C: N ratio in the shell of individuals from the TA-downregulated group was significantly lower than that of the other two groups, indicating that less inorganic carbon was added to the shell. As a result, abalone grew lighter and thinner shells in TA-downregulated seawater. Although seawater was not acidified, TA downregulation also caused a reduction in the calcium carbonate saturation state (Ω), which induced the erosion of the surface shell and the interruption of calcium carbonate generation. In conclusion, although seawater pH remained at ambient levels, the lowered CO 2 buffering capacity and Ω induced by seawater TA downregulation also showed a detrimental effect on the growth and calcification of Pacific abalone. The impact of ocean acidification on the growth of abalone should not be assessed using only seawater pH and/or pCO 2 but rather taking into account all of carbonate chemistry, particularly the CO 2 buffering capacity. Abalone cultivation is suggested to be carried out in seawater with a higher level of CO 2 buffering capacity and Ω, which can be achieved through integrated culture with seaweed or increasing the seawater TA level., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

In this paper current knowledge on the diversity of the gastropod cephalaspidean genus Haminoea from India is revised. A comprehensive literature review was undertaken and novel specimens were collected. Specimens from India were DNA barcoded using the gene cytochrome c oxidase sub-unit I and a Bayesian gene tree together with an Automatic Barcode Gap Discovery (ABGD) species delimitation analysis were inferred to compare Indian samples with species from the Indo-West Pacific. The most comprehensive DNA data set to date of the genus Haminoea is included and new morpho-anatomical features of Indo-West Pacific species were generated through fine anatomical work and scanning electron microscopy. A critical appraisal of previous records of the country is included and a new species, Haminoea aptei sp. nov., is described from the Andaman Islands and Lakshadweep Islands, India. www.zoobank.org/urn:lsid:zoobank.org:pub:90C191A9-5CA6-4BC6-84E3-B1A26674FA1B [ABSTRACT FROM AUTHOR]

Our work is a contribution to the study of the morphometric dissimilarity of the limpet Patella caerulea (Linnaeus, 1758) inhabiting the seashore of the western Mediterranean Sea. For this study, 438 individuals of this species were sampled in 24 stations and separated into 2 groups of individuals: the first group (G1) originating from the upper infralittoral and the lower mediolittoral areas, and the second group (G2) originating from the upper mediolittoral area. The biometry of P. caerulea has been studied by considering the total length (L), the total width (W), and the total height (H) of the shell. These parameters revealed a strong positive correlation, and were used for the principal component analysis (PCA). Other combined parameters (L/W, L/H, and W/H) were added for the discriminant function analysis (DFA). Both multivariate analyses showed that both groups (G1 and G2) were well separated. The morphometric survey based on the calculation of the geometric mean (GM) and the gibbosity index (GIB) revealed the existence of a morphological dissimilarity between the shells of groups G1 (flattened and stocky) and G2 (high and short). This morphological dissimilarity is discussed and compared with the results of other works on the same species and other related species. [ABSTRACT FROM AUTHOR]

Animal physiology and ecology are affected by increasing environmental temperatures, and this is particularly relevant in the tropics, where organisms are already living on the warm edge of their thermal windows. Here, we present data on sub-lethal effects of temperature (using molecular biomarkers), thermal tolerance, warming safety margins and body size shifts of a gastropod ( Stramonita haemastoma ) from tropical rocky shores, under an experimental setup of a climate warming scenario. Heat shock response, protein damage, antioxidant activity and lipid damage were all evaluated once a week during one month of exposure at a control temperature, and at an experimental temperature of plus 3 °C. Significant increase of heat shock protein response, lipid peroxides and catalase at the elevated temperature suggest the activation of cytoprotective pathways as response to an increased thermal load. Duration of exposure also had a significant influence in the animals’ responses, since whole body thermal tolerance only showed acclimation potential in the short-term, but not in the long-term. Thermal safety margin was low for this species, suggesting a narrow ability to tolerate further warming. Smaller body sizes were observed in specimens exposed to increased temperature, suggesting the occurrence of slower growth and possible changes in energy metabolism. Hence, enduring thermal stress, as predicted if present day warming trends are not reversed, may compromise populations of tropical marine snails. [ABSTRACT FROM AUTHOR]

Carbamate insecticides such as carbaryl and organophosphates such as azinphos-methyl share the ability to inhibit the activity of B-esterases. This study aimed to (1) assess the inhibitory effects of carbaryl on B-esterase activity in soft tissues and hemolymph of Planorbarius corneus ; (2) establish whether binary mixtures of carbaryl and azinphos-methyl depart or not from a model of concentration addition on the inhibition of cholinesterase activity; (3) determine the bioconcentration and elimination of the pesticides. The results showed that exposure of gastropods to increasing concentrations of carbaryl (0.1–5 mg L −1 ) for 48 h inhibited cholinesterase activity in a concentration-dependent manner, with an EC 50 of 1.4 ± 0.3 mg L −1 and 1.2 ± 0.1 mg L −1 for soft tissue and hemolymph, respectively. Carboxylesterase activity, measured with the substrates p-nitrophenyl butyrate and p-nitrophenyl acetate, was between 2.3 and 25 times more sensitive to carbaryl inhibition than cholinesterase activity. Binary mixtures corresponding to 0.5 EC 50 carbaryl + 0.5 EC 50 azinphos-methyl and 0.75 EC 50 carbaryl + 0.75 EC 50 azinphos-methyl produced inhibitions of cholinesterase activity similar to those of individual pesticides, following a model of concentration addition. Bioconcentration was analyzed using a one-compartment model. The absorption kinetics ( k 1 ) for both pesticides alone (1.4 mg L −1 of carbaryl or 1.8 mg L −1 of azinphos-methyl) or mixed (1.4 mg L −1 of carbaryl + 1.8 mg L −1 of azinphos-methyl) were similar. The elimination kinetics ratio ( k 2 ) estimated for the pesticides alone or in the mixtures showed that carbaryl was eliminated 3.5 times faster than azinphos-methyl. These results suggest that exposure of Planorbarius corneus to binary mixtures of carbaryl and azinphos-methyl for 48 h follow a concentration addition model on inhibition of cholinesterase activity and that the pesticide mixtures do not change the toxicokinetic parameters of the parent compounds. [ABSTRACT FROM AUTHOR]

The development of male genital tract by female gastropods, or imposex, can be caused by the tributyltin used in antifouling paints. A spatial survey of imposex in the gastropod Stramonita haemastoma was conducted across five Western Mediterranean and eleven North-Eastern Atlantic sites, in order to monitor the effectiveness of the tributyltin regulation imposed in the International Maritime Organisation. Imposex still occurs in eight out of eleven Mediterranean sites and in three out of five Atlantic sites. Extreme values of imposex incidence (I%) and degree (VDSI) were recorded in Tunisia, mainly in Bizerta channel (I% = 96.2%, VDSI = 0.96). However, the Relative Penis Length index (RPLI) was higher in Western Mediterranean sites where values varied between 0.56 in Algiers (Algeria) and 11.80 in Bouznika (Morocco). In the European sites, moderate to low imposex level and degree were recorded. All the affected sites were below the Ecotoxicological Assessment Criteria (EAC) derived for TBT. [ABSTRACT FROM AUTHOR]

In response to the need to assess the ecological quality or health of marine benthic habitats, there has been a proliferation of biotic indices based on soft sediment macrofaunal communities. While shown to be useful in areas where they have been developed, some indices may not be readily transferrable to other regions due to differences in species ecology or composition, stressor type or magnitude, and natural variability. Using a national New Zealand dataset compiled from estuary monitoring data for 2001–2016, we used linear mixed models to determine the effect of multiple stressors (sediment mud content, metals and total phosphorus) and natural variability (associated with space, estuary type and time) on nine indices developed in New Zealand and overseas. The Richness-Integrated AZTI Marine Biotic Index (RI-AMBI), a modification of a popular overseas biotic index, had the most variation explained by stressors overall (marginal pseudo-R 2 = 0.22 compared to ≤0.15 for all other indices). This variation was primarily explained by a single stressor, sediment mud content, which is the dominant stressor in New Zealand estuaries. However, although the overall variation explained by stressors was lower for all other indices, multiple, rather than single, stressors had significant effects on some indices. For example all three stressors had a significant effect on the Traits Based Index, and the variation explained by metals was highest for this index. Relatively high amounts of natural and unexplained variation for all indices suggested that further understanding is required before operational implementation of indices at a national scale. Thus, the use of more than one index, i.e. a weight of evidence approach, is suggested to minimise uncertainty related to inaccuracy and misclassification of ecological health in New Zealand estuaries. [ABSTRACT FROM AUTHOR]

Abstract: Ramshorn snail (Helisoma anceps) is a freshwater gastropod found all over North America and is also an essential component to the larval and juvenile culture of endangered Delta Smelt (Hypomesus transpacificus) at the UC Davis Fish Conservation and Culture Lab (FCCL). H. anceps has been proven effective in cleaning the excess algae while not harming the larvae. A challenge at the FCCL has been having a reliable source of these snails, since previously it has been dependent upon nature and never guaranteed there would be enough to meet the needs of the FCCL. Experiments were conducted to assess the effects of temperature, food types, rearing density and total ammonia nitrogen (TAN) concentrations. Procedures recommended to increase snail fecundity for the FCCL are to rear spawning parent snails and the resultant eggs at a high temperature (16–20°C) and with a low TAN concentration (0–5 mg/L). Newly hatched snails need to be cultured at a low density (about one snail/20 cm2). After the snails grow to an acceptable size (1.3 cm diameter), they could be set aside and cultured in an environment with less optimal water quality parameters such as a high TAN level (as high as 20 mg/L) and low temperature (12°C) for quantity control prior to use. [ABSTRACT FROM AUTHOR]

The taxonomic status of the limacoid genus Macrochlamys Gray, 1847 in Thailand has long been plagued by much ambiguity due to the inability to distinguish members from each other, and a few other genera, by shell morphology alone. The taxonomy of the Thai species is evaluated resulting in recognition of seven species, including five new species. The new species, Macrochlamys aurantia, M. coleus and M. tanymentula from Kanchanaburi Province (West Thailand), and M. caverna and M. lemma from Lopburi Province (Central Thailand), are distinguished and described based on shell, animal colouration, radula and genitalia characters. The status of Macrochlamys brunnea Möllendorff, 1902b is at present unclear. Although described from Bangkok, no material identifiable as this species was found in recent extensive surveys and it is provisionally retained in the genus without anatomical evaluation. Macrochlamys kelantanensis Möllendorff, 1902a is re-described with additional morphological and anatomical information. The five new species appear to have a restricted distribution in Western and Central Thailand, whereas M. kelantanensis is more wide-ranging, from Thailand to Malaysia. Detailed descriptions and illustrations of the shell morphology, external morphology, genital anatomy and radulae are provided. The results show that despite the shells being morphologically similar, aspects of classical morphology based taxonomy for Macrochlamys species, especially the genitalia morphology, remain useful and reliable for species delimitation. [ABSTRACT FROM AUTHOR]

The contribution of food sources to the freshwater gastropod Bellamya aeruginosa was estimated using stable carbon and nitrogen isotope ratios in three water bodies (two reservoirs and a pond) with different history of cyanobacterial blooms in the eastern part of Zhejiang Province, China. Results of the isotope mixing model showed that filtered food materials (suspended particulate organic matter) contributed most to the diet of B. aeruginosa in both reservoirs with higher levels of chlorophyll a (Chl a) in the water column, except during the summer, when a cyanobacteria (Microcystis) bloom occurred in Reservoir Tingxia. In contrast, scraped food materials (benthic detritus) contributed most to the diet of B. aeruginosa in the pond, where low levels of Chl a were found in the water column. These results suggest that although filtered food materials were the main food source of B. aeruginosa when the habitat was rich in desirable suspended particles, ingestion of filtered food materials decreased during the cyanobacteria bloom. Feeding experiments were conducted to verify whether snails could avoid ingesting the cyanobacteria. The isotopic ratios in muscle tissue of B. aeruginosa fed by a diet containing only cyanobacteria were similar to those of the no-diet treatment, implying that the snails did not feed, when only cyanobacteria were offered. Moreover, the combination of higher mortality, lower fecal pellet counts, and reduced growth (based on shell height) in the treatment with cyanobacteria indicate that B. aeruginosa stopped feeding when food became undesirable, confirming our field observations that B. aeruginosa avoids feeding on toxic cyanobacteria. [ABSTRACT FROM AUTHOR]

Accurate estimation of biodiversity is necessary to provide a baseline for further ecosystem investigations and protection of High Arctic regions. Novaya Zemlya is a large Arctic archipelago located on the border between the Barents and Kara Seas. Despite a long history of investigation, data on species composition along the coast of Novaya Zemlya are presented only in sources from the initial period of investigation in the late 19th to early 20th century. We estimate herein the diversity of shell-bearing Gastropoda found along the western coast of Novaya Zemlya, based on both published sources and our original identification of material collected between 1985 and 2008. The total species list contains 86 species, 24 of which were identified only from the recent material, while 28 were only reported in literature. Our results demonstrate that modern and historical data are significantly different. However, these differences do not indicate any changes in species composition in the region during the last century, but rather arise for methodological reasons. Even combined, the two types of data do not provide complete coverage of the fauna. We also carried out a preliminary comparison between local coastal gastropod faunas from various parts of the Barents Sea (including Novaya Zemlya). [ABSTRACT FROM AUTHOR]

Integrative taxonomy, and in particular species delimitation using molecular data, often leads to the discovery of new species. However, these new species are not systematically turned into formally described species, because, among other reasons, linking molecularly defined groups with available taxonomic names can be tricky. Here we delimit species in the genus Lophiotoma (Gastropoda, Conoidea, Turridae) using two unlinked genetic markers (the mitochondrial COI gene and the nuclear 28S ribosomal RNA gene), shell and radula characters, and geographic and bathymetric distribution. Several methods of species delimitation (ABGD, GMYC and PTP) resulted in several alternate species partitions, discussed using an integrative approach. We ended up with ten different species, among which seven have been unequivocally linked to available species names. We designate neotypes for two of them (L. acuta, L. jickelii). The three remaining species are described as new: L. semfala sp. nov., L. bratasusa sp. nov. and L. kina sp. nov. We discuss the difficulties encountered in locating type specimens and in linking them to recognized molecular species, in a context where the vast majority of mollusc types are empty, dried shells and consequently difficult to sequence. [ABSTRACT FROM AUTHOR]

Organisms on rocky shores are frequently exposed to high temperatures, which cause impairment of cardiac function and retard cellular oxygen delivery. However, some gastropods can survive at several degrees Celsius higher than their Arrhenius break temperature of cardiac function (ABT), indicating the importance of anaerobic metabolism for their thermal tolerance. We measured the global molecular responses to heat stress in limpet Cellana toreuma using 454 GS-FLX to investigate the variations of genes involved in anaerobic metabolism at high temperatures. Next, the gene expression levels of 4 anaerobic enzymes and activity of alanopine dehydrogenase (AlDH), which is involved in opine pathway, were measured in response to elevated temperature. A total of 19 heat shock proteins (HSPs) were determined using real-time PCR at different temperatures. At high temperatures, the extensive upregulation of HSP genes was an effective but energetically expensive form of protection to prevent thermal damage. The upregulation of hypoxia-inducible factor 1 alpha mRNA indicated the condition of cellular hypoxia and the high gene expression and enzyme activity of AlDH suggested that opine pathway was the main anaerobic pathway. These results implied that anaerobic metabolism was enhanced to provide energy in the face of thermal stress. Our findings highlight the ecological significance of the anaerobic metabolism of gastropods to thermal adaptation. For predicting the ecological impact of global warming on the distribution of gastropods, the role of anaerobic pathways should be evaluated. [ABSTRACT FROM AUTHOR]

Large, sinistrally coiled gastropod species have been reported under the genus name Kosovia Atanacković, 1959 from middle and late Miocene palaeolakes of central Serbia and Kosovo. Despite several papers dealing with the taxonomy and evolution of this genus, its systematic position and possible ancestry have been unresolved. Previously, it has been suggested that it may be a member of the Viviparidae, Lymnaeidae or Planorbidae, but without morphological criteria to support these assertions. In order to elucidate the systematic position of the genus, we investigated type material of the type species Kosovia matejici Pavlović, 1931, which is the oldest representative and is restricted to middle Miocene deposits of central Serbia. Embryonic shell characters support membership of the Planorbidae. Based on the congruence of all evaluated morphological characteristics, we attribute the species to the genus Bulinus, which makes Kosovia a junior subjective synonym of Bulinus. We discuss potential ancestry of the oldest representative and relationships among the species previously attributed to Kosovia. Our study emphasizes the importance of SEM-based examination of the protoconch to clarify the systematic position of problematic freshwater gastropods, especially when molecular data are absent. [ABSTRACT FROM AUTHOR]

This study investigated the possible biological, biochemical and histological changes in Bradybaena similaris ( Gastropoda: Pulmonata) infected by Heterorhabditis indica (Rhabditida: Heterorhabditidae), strain LPP1. Two groups of 16 snails were formed: the control group (unexposed) and the treated group, which was exposed for three weeks to infective juveniles (J 3 ) of H. indica LPP1. The experiment was conducted in duplicate, using a total of 64 snails. After the exposure period, the snails were dissected to collect the hemolymph and tissues, for evaluation of the physiological changes caused by the infection. The number of eggs laid/snail and the viability of these eggs were also assessed as indicators of the reproductive activity of B. similaris . Intense glycogenolysis was accompanied by a significant reduction ( p < 0.05) in the glucose content of the hemolymph of the exposed snails, indicating that infection by H. indica induces breakdown of the host's glycemic homeostasis. Significant variations ( p < 0.05) in the lactate dehydrogenase activity occurred together with changes in the concentration of pyruvic and lactic acid in the hemolymph of the infected B. similaris snails, corroborating the transition from aerobic to anaerobic metabolism in the hosts. These metabolic alterations reflect the parasitic castration process in this interface. The results suggest that the use of H. indica LPP1 is a potential alternative for biological control of B. similaris. [ABSTRACT FROM AUTHOR]

5-Hydroxymethylcytosine (5hmC) is an important, yet poorly understood epigenetic DNA modification, especially in invertebrates. Aberrant genome-wide 5hmC levels have been associated with cadmium (Cd) exposure in humans, but such information is lacking for invertebrate bioindicators. Here, we aimed to determine whether this epigenetic mark is present in DNA of the hepatopancreas of the land snail Cantareus aspersus and is responsive to Cd exposure. Adult snails were reared under laboratory conditions and exposed to graded amounts of dietary cadmium for 14 days. Weight gain was used as a sublethal endpoint, whereas survival as a lethal endpoint. Our results are the first to provide evidence for the presence of 5hmC in DNA of terrestrial mollusks; 5hmC levels are generally low with the measured values falling below 0.03%. This is also the first study to investigate the interplay of Cd with DNA hydroxymethylation levels in a non-human animal study system. Cadmium retention in the hepatopancreas of C. aspersus increased from a dietary Cd dose of 1 milligram per kilogram dry weight (mg/kg d. wt). For the same treatment, we identified the only significant elevation in percentage of samples with detectable 5hmC levels despite the lack of significant mortalities and changes in weight gain among treatment groups. These findings indicate that 5hmC is an epigenetic mark that may be responsive to Cd exposure, thereby opening a new aspect to invertebrate environmental epigenetics. [ABSTRACT FROM AUTHOR]

A new diplommatinid genus, Luzonocoptis Páll-Gergely & Hunyadi, gen. n. is erected for two new species, Luzonocoptis antenna Páll-Gergely & Hunyadi, sp. n. and L. angulata Páll-Gergely & Hunyadi, sp. n. Both species inhabit the northeastern part of Luzon Island, Philippines. The genus Luzonocoptis gen. n. is mostly characterized by a very slender shell with 14-18 whorls, a strongly expanded peristome, an interrupted, weak columellar lamella, the absence of any additional plicae or lamellae, and a rachidian tooth having five cusps. [ABSTRACT FROM AUTHOR]

In marine environments, connectivity among populations of benthic invertebrates is provided primarily by dispersion of larvae, with the duration of pelagic larval phase (PLD) supposed to represent one of the major factor affecting connectivity. In marine gastropods, PLD is linked to specific larval development types, which may be entirely intracapsular (thus lacking a pelagic dispersal), or include a short pelagic lecithotrophic or a long planktotrophic phase. In the present study, we investigated two sibling species of the cosmopolitan neogastropod genus Columbella (commonly known as dove shells): Columbella adansoni Menke, 1853, from the Macaronesian Atlantic archipelagos, with planktotrophic development, and Columbella rustica Linnaeus, 1758, from the Mediterranean Sea, with intracapsular development. We expected to find differences between these two sister species, in terms of phylogeographic structure, levels of genetic diversification and spatial distribution of genetic diversity, if PLD was actually a relevant factor affecting connectivity. By analysing the sequence variation at the cytochrome c oxidase subunit I (COI) in 167 specimens of the two species, collected over a comparable geographic range, we found that Columbella adansoni, the species with planktotrophic development, and thus longer PLD, showed no phylogeographic structure, lower levels of genetic diversity, interpopulational variance lower than the intrapopulational one and no spatial structure in the distribution of the genetic diversity; Columbella rustica , the species with intracapsular development, thus with evidently lower dispersal abilities, showed a clear phylogeographic structure, higher levels of genetic diversity, high interpopulational and low intrapopulational variance, and a clear signature of global spatial structure in the distribution of the genetic diversity. Thus, in this study, two sibling species differing almost only in their larval ecology (and PLD), when compared for their genetic variation showed patterns supporting the hypothesis that PLD is a major factor affecting genetic connectivity. Therefore, it seems reasonable to expect that the ecological attributes of the marine communities - also in terms of the variation in larval ecology of the species involved – are taken into the due consideration in conservation actions, like the design of marine protected areas networks. [ABSTRACT FROM AUTHOR]

Human adenovirus (HAdV) is resistant to environment and can be used as a marker to detect fecal contamination. Considering the importance of freshwater snails in the aquatic environment, their use as concentrators for HAdV is a complementary tool for viral analysis of water. The goal of the study was to detect HAdV in snails and surface water collected from wetlands of the Sinos River (Rio Grande do Sul, Brazil) basin and to compare rates and viral loads found in both samples. HAdV was detected through real-time PCR. Total and fecal coliforms were detected by Colilert kit, and viral infectivity of positive samples of the DNA genome was performed in A549 human cell line. All wetlands presented bacterial and viral contamination, but no viral particle was considered viable. The wetland that showed lower fecal coliform mean was Campo Bom, and São Leopoldo (both cities in Rio Grande do Sul) was representative of the highest mean. HAdV was detected in water samples (53%), gastropods' hemolymph (31%) and tissues (16%). Wetlands proved to be environments already altered by human action. Water samples exhibited a higher frequency of HAdV detection; however, in some instances, the target viral genomes were only found in gastropod biological samples. This was a pioneer study in the use of freshwater snails for human enteric viral assessment thus demonstrating that the human organism can retain fecal contamination, complementing and assisting in microbiological water analyzes. [ABSTRACT FROM AUTHOR]

Sabah, a Malaysian state at the north-eastern tip of Borneo, is situated in one of the Earth's biodiversity hotspots yet its freshwater gastropod diversity remains poorly known. An annotated checklist of the freshwater gastropods is presented, based on specimens deposited in the BORNEENSIS collection of the Institute for Tropical Biology and Conservation at Universiti Malaysia Sabah, Malaysia. A KMZ file is also provided, which acts as a repository of digital images and complete collection data of all examined material, so that it can be shared and adapted to facilitate future research. [ABSTRACT FROM AUTHOR]

Sabah, situated in one of the world's biodiversity hotspots, has the largest number of islands in Malaysia with more than 500 of various sizes and degrees of isolation. However, information on the islands' biodiversity is limited. This study provides an up-to-date checklist of land snail species found on 24 west coast islands in Sabah. A total of 67 species (nearly 20% of the total number of land snail species in the state) representing 37 genera and 19 families is enumerated based on systematic field surveys of 133 sampling plots, BORNEENSIS database records and species checklists published between 2000 and 2016. The number of species on the islands ranges from four to 29. Labuan Island has the highest number of species (29), followed by Tiga Island (25), Mantanani Besar Island (24) and Gaya Island (23). However, the populations of some land snail species may have declined as several previously recorded species on the islands were not found in a recent systematic field sampling. This checklist is provided as a baseline inventory for future island land snail studies and to better inform biodiversity conservation plans of marine parks and other islands on the Sabah west coast. [ABSTRACT FROM AUTHOR]

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