Intertidal Bivalves Research Articles

Environmental effects on abundance and size of harvested bivalve populations in intertidal shellfish grounds

Clams, razor clams and cockle are intertidal bivalve species collected on foot in the shellfish grounds of the Rías Altas (NW Spain). Spatio-temporal distribution of these bivalves are typically at the expenses of the environmental conditions of the region; however, the responses to the abiotic conditions are poorly understood. Using data from 6 species (Ruditapes decussatus, Venerupis corrugata, Ruditapes philippinarum, Cerastoderam edule, Donax trunculus and Solen marginatus) sampled in 51 intertidal shellfish grounds during 2007 and 2008, we characterized the influence of the environment (temperature, salinity, nutrient salts, suspended organic matter, or sediment granulometry and composition) on the distribution and size of these species through a comparative statistical analysis. Shellfish grounds were grouped according to their sediment and water characteristics revealing a land-ocean gradient and the influence of the geological imprint that separates bivalve grounds from West to East. Statistical models showed that R. decussatus, V. corrugata and R. philippinarum together with C. edule were more abundant in sites combining a strong marine influence with organic-rich finer sediments. However, each of those species also had different environmental niches mostly related to their particular sediment affinities, the proximity to the river mouth, and their physiological tolerances to temperature and salinity. D. trunculus was only found in outer exposed shellfish grounds, while S. marginatus abundance increased in muddy sediments. River distance was a sound descriptor of individual shell length and length variability with contrasting effects on the different species. Furthermore, slopes of length-weight relationships were steeper in autumn than in spring, and this allometry tended to be more positive in sites located closer to the rivers’ mouth, which had a higher organic matter C/N ratio. Overall, harvested intertidal bivalves had identifiable environmental preferences that influence their spatial distribution in abundance, body size, and allometric growth.

Short-term effects of an unprecedented heatwave on intertidal bivalve populations: fisheries management surveys provide an incomplete picture

IntroductionCoastal marine ecosystems, are particularly susceptible to climate change. One such threat is atmospheric heatwaves, which are predicted to increase in frequency, duration, and intensity. Many intertidal organisms already live at the edge of their thermal tolerance limits and heatwaves can outstretch an organism’s ability to compensate in the short term. In June 2021 the Pacific Northwest region of North America, including the Salish Sea, experienced a significant atmospheric heatwave during some of the lowest tides of the year. This was followed by numerous reports of dead and dying intertidal marine organisms region-wide. A semi-quantitative rapid assessment found a range of both species- and location-specific effects but generally recorded widespread negative impacts to intertidal shellfish species across the Salish Sea. MethodsFollowing these results, we opportunistically analyzed data collected by intertidal bivalve resource managers from the region. These datasets allowed us to examine regional density and size data for clam and oyster populations before and after the heatwave to increase our quantitative understanding of heatwave effects. ResultsWe found a range of responses including positive and negative effects of the heatwave on clam and oyster density. While we generally found small changes in bivalve size, some site-species combinations displayed large shifts in size frequency. Many of our analyses did not indicate even moderate statistical support, even with large changes in the mean, driven in part by high variability in the data. Time intervals between surveys, ranging from 2 to over 25 months, had little effect on observed variability indicating that any heatwave-induced effects may be masked by variability inherent to the population ecology and/or survey methodology. DiscussionThis analysis has highlighted the need for intertidal resource managers, and the greater research community, to consider alternative survey approaches designed to constrain variability in order to detect the effects of acute or extreme events. With the effects of climate change predicted to become more intense, targeted survey approaches may be needed to detect the effects and implications of such events and to continue effective management of intertidal bivalves in the Salish Sea and worldwide.

First Report of Glauconome chinensis (Gray, 1828) from West Bengal-Odisha Coast, India

The intertidal marine bivalve Glauconome chinensis (Chinese glauconome), Gray 1828 is a burrowing benthic fauna inhabiting in soft muddy to sandy sediments of Western pacific mangrove areas. The specimen is characterised by long siphon (inhalant and exhalent) for feeding and a prominent foot for locomotion. They are mostly gonochoric, few are sometimes protandric hermaphrodites. According to Gray’s description their embryonic development starts through free swimming trochophore larvae and succeeded by the veliger. Glauconome chinensis has been rediscovered for the first time from the intertidal coastal mangrove areas of Talsari, confluence of Subarnarekha estuary of West Bengal-Odisha coast, India. Quadrates having areas of 1m² were placed randomly on study sites and the studied specimens were unearthed, counted their size, biomas, population density and distribution pattern. Physico-chemical parameters were also evaluated. For anatomical study tissues were fixed in 4% formalin solution and processed through alcoholic grades. Body length, siphon, gill, mantle, foot, adductor muscles, digestive gland and gonads were examined. The studied specimens were stayed in 10-40cm depth from sediment surface and showed clumped distribution pattern. The mean length, width and biomass of the specimen were 39.2(mm) ±0.393, 14.5(mm) ±0.351and 3.89(gm) ±0.382 respectively. The report on the occurrence of such intertidal bivalve adds relevant data for the good assessment of food chain and food web of marine coastal mangrove ecosystem. The present study also aims to gather knowledge of valuable ecological services of Glauconome chinensis and to maintain the biological integrity of West Bengal-Odisha coastal region with Bay of Bengal.

Intertidal Bivalve Diversity and Fishery of the Gosthani Estuary, Bhimunipatnam, Visakhapatnam, East Coast of India

The results of the present investigation revealed that the occurrence of 13 species belonging to class bivalvia were dominant taxa in the Gosthani estuary. Out of 13 species 6 orders, 8 families, and 11 genera were observed from April 2023 to March 2024. The samples were obtained by handpicking, digging, and trawling with bare feet by fisher community. A field survey was conducted to collect data on mollusc species, stocks, distribution, and marketing. The bivalves were collected from the bycatch for identification, mostly based on shell morphology, hinge, interlocking dentition, etc., with reference to the standard literature In this present study data was collected and analysed from fishermen community and traders. The Crassostrea madrasensis was more dominant availability species, its contributes to highest collection 5.867 T/ year and 2.78T in Apr-23, followed by Meretrix casta 2.78 T Meretrix meretrix 1.18 T, Anadara rhombea 0.87, Tegillarca granosa 0.759 and followed by other species. According to IUCN status 13 species contributed to 53.84% are not evaluated (NE), followed by data deficient (DD) with 30.76%, and least concerned 15.38%. The monthly available bivalves at Gosthani estuary the data was comparison for abundance. The difference between the sample averages of all groups is not big enough to be statistically significant. The results of ANOVA for p-value of 0.97 indicate significant support for H0. The p-value equals to 0.231 indicates a greater support for H0.

Resistance of an intertidal oyster(Saccostrea mordax)to marine heatwaves and the implication for reef building

Marine heatwaves (MHWs) have a significant impact on intertidal bivalves and the ecosystems they sustain, causing the destruction of organisms' original habitats. Saccostrea mordax mainly inhabits the intertidal zone around the equator, exhibiting potential tolerance to high temperatures and maybe a species suitable for habitat restoration. However, an understanding about the tolerance mechanism of S. mordax to high temperatures is unclear. It is also unknown the extent to which S. mordax can tolerate repeated heatwaves of increasing intensity and frequency. Here, we simulated the effects of two scenarios of MHWs and measured the physiological and biochemical responses and gene expression spectrum of S. mordax. The predicted responses varied greatly across heatwaves, and no heatwave had a significant impact on the survival of S. mordax. Specifically, there were no statistically significant changes apparent in the standard metabolic rate and the activities of enzymes of the oyster during repeated heatwaves. S. mordax exposed to high-intensity heatwaves enhanced their standard metabolic rate to fuel essential physiological maintenance and increasing activity of SOD and expression of HSP70/90. These strategies are presumably at the expense of functions related to immunity and growth, as best exemplified by significant depressions in activities of enzymes (NaK, CaMg, T-ATP, and AKP) and expression levels of genes (Rab, eEF-2, HMGR, Rac1, SGK, Rab8, etc.). The performance status of S. mordax tends to improve by implementing a suite of less energy-costly compensatory mechanisms at various levels of biological organization when re-exposed to heatwaves. The adaptive abilities shown by S. mordax indicate that they can play a crucial role in the restoration of oyster reefs in tropical seas.

Hard clam resilience to marine heatwaves in the face of climate change

The frequency and severity of marine heatwaves (MHWs) have reached new heights in the last two decades. Intensifying MHWs can affect intertidal bivalves, but the extent of their impacts remains largely underestimated. Here, we tested how persistent (P-MHW) and repeated (R-MHW) MHWs events affected the physiological energetics of ecologically and economically clams Mercenaria mercenaria inhabiting intertidal habitats. Compared to individuals maintained under ambient conditions, the clams exposed to both two scenarios of MHWs exhibited significant increases in their clearance rate, absorption efficiency, respiration rate, excretion rate, and scope for growth, showing compensatory energetic mechanisms to cope with MHWs. Especially, physiological energetics of M. mercenaria were more sensitive to repeated than persistent scenarios of MHWs. Given that the physiological response can act as an early and sensitive indicator of the fitness of intertidal bivalves, our results indicated that M. merceneria can likely hold the ability to readily recover from repeated to persistent exposure MHWs, enabling its continued resilience in a rapidly changing marine environment.

Behavioral responses of intertidal clams to compound extreme weather and climate events

Rapidly increasing concentration of carbon dioxide (CO2) in the atmosphere not only results in global warming, but also drives increasing seawater acidification. Infaunal bivalves play critical roles in benthic-pelagic coupling, but little is known about their behavioral responses to compound climate events. Here, we tested how heatwaves and acidification affected the behavior of Manila clams (Ruditapes philippinarum). Under acidified conditions, the clams remained capable of burrowing into sediments. Yet, when heatwaves attacked, significant decreases in burrowing ability occurred. Following two consecutive events of heatwaves, the clams exhibited rapid behavioral acclimation. The present study showed that the behavior of R. philippinarum is more sensitive to heatwaves than acidification. Given that the behavior can act as an early and sensitive indicator of the fitness of intertidal bivalves, whether, and to what extent, behavioral acclimation can persist under scenarios of intensifying heatwaves in the context of ocean acidification deserve further investigations.

Evaluation of species thermal sensitivity with individual-based physiological performance

Ignoring intraspecific variations can prevent us from accurately assessing species' thermal sensitivity to global warming. Individual-based physiological performance provides a feasible solution to depict species' thermal sensitivity using a bottom-up approach. We measured the cardiac performance of intertidal bivalves (1159 individuals from multiple populations of six bivalves), determined the upper thermal limit of each individual, calculated the proportions of individuals suffering sublethal/lethal heat stress, and mapped sensitive regions to high temperatures. Results showed that high inter-individual variations of physiological performance existed in levels of populations and species, and species’ thermal sensitivity was positively related to the intraspecific variations of heat tolerance. This bottom-up approach scaled up from individual, population to species emphasizes the importance of individual-based physiology performance in assessing thermal sensitivity across different hierarchical levels and enables better evaluating and forecasting of species responses to global warming.

Combined effects of salinity and intermittent hypoxia on mitochondrial capacity and reactive oxygen species efflux in the Pacific oyster, Crassostrea gigas.

Coastal environments commonly experience fluctuations in salinity and hypoxia-reoxygenation (H/R) stress that can negatively affect mitochondrial functions of marine organisms. Although intertidal bivalves are adapted to these conditions, the mechanisms that sustain mitochondrial integrity and function are not well understood. We determined the rates of respiration and reactive oxygen species (ROS) efflux in the mitochondria of oysters, Crassostrea gigas, acclimated to high (33 psu) or low (15 psu) salinity, and exposed to either normoxic conditions (control; 21% O2) or short-term hypoxia (24 h at <0.01% O2) and subsequent reoxygenation (1.5 h at 21% O2). Further, we exposed isolated mitochondria to anoxia in vitro to assess their ability to recover from acute (∼10 min) oxygen deficiency (<0.01% O2). Our results showed that mitochondria of oysters acclimated to high or low salinity did not show severe damage and dysfunction during H/R stress, consistent with the hypoxia tolerance of C. gigas. However, acclimation to low salinity led to improved mitochondrial performance and plasticity, indicating that 15psu might be closer to the metabolic optimum of C. gigas than 33psu. Thus, acclimation to low salinity increased mitochondrial oxidative phosphorylation rate and coupling efficiency and stimulated mitochondrial respiration after acute H/R stress. However, elevated ROS efflux in the mitochondria of low-salinity-acclimated oysters after acute H/R stress indicates a possible trade-off of higher respiration. The high plasticity and stress tolerance of C. gigas mitochondria may contribute to the success of this invasive species and facilitate its further expansion into brackish regions such as the Baltic Sea.

Physiological and biochemical responses of clams to recurrent marine heatwaves

In the past decade, the frequency, intensity and duration of marine heatwaves (MHWs) in the South China Sea have been increasing strikingly, resulting in serious impacts on intertidal bivalves and their ecosystems. The Manila clam, Ruditapes philippinarum, is one of the most ecologically and economically important bivalve species in the South China Sea, yet very little is known about its fate under intensifying MHWs events. Here, we examined how R. philippinarum responded to two consecutive scenarios of MHWs, with each composed of 4 °C and 8 °C rises of seawater temperatures, respectively. Up to 87% of Manila clams survived recurrent MHWs events, and significant increases in standard metabolic rate occurred predominantly under extreme conditions (+8 °C), indicating that the clams could trigger compensatory mechanisms to mitigate MHWs-induced thermal stress. Following acute and repeated exposures to MHWs, Manila clams showed similar responses in enzymes underpinning energy metabolism (NKA, CMA, and T-ATP), antioxidant defence (SOD, CAT, and MDA), and biomineralization (AKP and ACP), most of which exhibited significantly increasing and then decreasing trends with the intensification of MHWs. Of eight genes associated with physiological tolerance and fitness, ATAD3A, PFK, SOD, and C3 were significantly down-regulated in response to recurrent MHWs events, demonstrating the certain resistance to MHWs. These findings provide a better understanding that marine bivalves hold the potential to acclimate simulated MHWs events from the physiological and molecular processes.

Radiological dose and associated risk due to 210Po in commercial inter-tidal bivalves of southwest (Arabian Sea) coast of India

The activity concentration of 210Po was determined in edible tissues of commercial bivalves on the southwest coast of India. The 210Po activity ranged from 38.3 ± 6.9 Bq kg−1 to 91.2 ± 18.6 Bq kg−1. The annual committed effective dose (ACED) and lifetime carcinogenic risk (LCR) were calculated for different age groups to determine the potential health risk associated with bivalve consumption. The average ACED ranged from 81.5 to 194.1 μSv y−1, with the 10th and 95th percentiles being 68 and 261 μSv y−1, respectively. Lifelong mortality risk (LMTR) values ranged from 1.2 × 10−3 to 2.9 × 10−3, while lifetime morbidity risk (LMBR) values ranged from 1.9 × 10−6 to 4.9 × 10−6. The effective dose was found to be within the UNSCEAR limits.

Post-responses of intertidal bivalves to recurrent heatwaves.

Heatwaves are becoming hotter, longer and more frequent, threatening the survival of intertidal bivalves and devastating their ecosystems. Yet, substantially overlooked are heatwave-induced post-responses, which are important to assess cascading consequences. Here, we investigated responses of intertidal bivalves, Ruditapes philippinarum, to recurrent heatwaves. Physiological and gene expression analyses demonstrated that the mantle tissue of R. philippinarum did not sensitively respond to heatwaves, but revealed post-responses under recovery scenarios. Of 20 genes related to essential physiology and fitness, 18 were down-regulated during the 1st recovery period, but following repeated exposure, 13 genes were up-regulated, in line with significantly increased activities of energy-metabolizing enzymes, and antioxidant and nonspecific enzymes. The down-regulation of genes involved in biomineralization, nevertheless, was observed under recovery scenarios, implying the trade-off between essential physiological and fitness-related functions. These findings pave the way for understanding the physiological plasticity of marine bivalves in response to intensifying heatwaves.

Assessing the impact of atmospheric heatwaves on intertidal clams

Heatwaves have become more frequent and intense in the last two decades, resulting in detrimental effects on marine bivalves and ecosystems they sustain. Intertidal clams inhabit the most physiologically challenging habitats in coastal areas and live already near their thermal tolerance limits. However, whether and to what extent atmospheric heatwaves affect intertidal bivalves remain poorly understood. Here, we investigated physiological responses of the Manila clam, Ruditapes philippinarum, to heatwaves at air temperature regimes of 40 °C and 50 °C occurring frequently and occasionally at the present day in the Beibu Gulf, South China Sea. With the increasing intensity of heatwaves and following only two days of aerial exposure, Manila clams suffered 100 % mortality at 50 °C, indicating that they succumb to near future heatwaves, although they survived under various scenarios of moderate heatwaves. The latter is couched in energetic terms across levels of biological organization. Specifically, Manila clams acutely exposed to heatwaves enhanced their standard metabolic rate to fuel essential physiological maintenance, such as increasing activities of SOD, CAT, MDA, and AKP, and expression of HSP70. These strategies occur likely at the expense of fitness-related functions, as best exemplified by significant depressions in activities of enzymes (NKA, CMA, and T-ATP) and expression levels of genes (PT, KHK, CA, CAS, TYR, TNF-BP, and OSER). When heatwaves occurred again, Manila clams can respond and acclimate to thermal stress by implementing a suite of more ATP-efficient and less energy-costly compensatory mechanisms at various levels of biological organization. It is consequently becoming imperative to uncover underlying mechanisms responsible for such positive response and rapid acclimation to recurrent heatwaves.

Evolutionary and ecological insights from vital staining of bivalve oocytes: A Red Queen at the sweepstakes?

AbstractTo determine the proportion of inviable oocytes that are spawned along with normal oocytes in marine bivalves, we turned to a time‐honored technique not previously used on invertebrate oocytes: the neutral red vital stain. Despite the difficulty in obtaining induced spawns from field‐collected Cerastoderma edule (L), the results and insights from this simple procedure to answer a simple question were unexpected and far‐reaching. Mean proportions of inviable oocytes in the spawns of cockle C. edule ranged from 35% to 85%, with the vast majority represented by atresic (autolyzing) oocytes. These levels are in agreement with previous quantitative histological observations of prespawning atresia in both C. edule and the Manila clam Tapes philippinarum. Such elevated prefertilization inviability mirrors the known high level of postfertilization inviability in bivalves. Together, these high levels of inviability may account for much of the early mortality in the type III survivorship curves typical of marine bivalves. The combination of high fecundity and high oocyte inviability suggests a Red Queen‐type reproductive dilemma in these species. In addition, the great degree of interindividual variation observed in oocyte inviability suggests that cockles, and perhaps other intertidal bivalves, present a Sweepstakes Reproductive Strategy, in which highly variable individual fecundity confronts a highly variable environment. The neutral red technique promises to be a useful tool for investigating prespawning inviability in other marine taxa, as well as for aquaculture, conservation, restocking, ecophysiology, and environmental monitoring.

Parasitism by metacercariae modulates the morphological, organic and mechanical responses of the shell of an intertidal bivalve to environmental drivers

Environmental variation alters biological interactions and their ecological and evolutionary consequences. In coastal systems, trematode parasites affect their hosts by disrupting their life-history traits. However, the effects of parasitism could be variable and dependent on the prevailing environmental conditions where the host-parasite interaction occurs. This study compared the effect of a trematode parasite in the family Renicolidae (metacercariae) on the body size and the shell organic and mechanical characteristics of the intertidal mussels Perumytilus purpuratus, inhabiting two environmentally contrasting localities in northern and central Chile (ca. 1600 km apart). Congruent with the environmental gradient along the Chilean coast, higher levels of temperature, salinity and pCO2, and a lower pH characterise the northern locality compared to that of central Chile. In the north, parasitised individuals showed lower body size and shell resistance than non-parasitised individuals, while in central Chile, the opposite pattern was observed. Protein level in the organic matter of the shell was lower in the parasitised hosts than in the non-parasitised ones regardless of the locality. However, an increase in polysaccharide levels was observed in the parasitised individuals from central Chile. These results evidence that body size and shell properties of P. purpuratus vary between local populations and that they respond differently when confronting the parasitism impacts. Considering that the parasite prevalence reaches around 50% in both populations, if parasitism is not included in the analysis, the true response of the host species would be masked by the effects of the parasite, skewing our understanding of how environmental variables will affect marine species. Considering parasitism and identifying its effects on host species faced with environmental drivers is essential to understand and accurately predict the ecological consequences of climate change.

Water quality and the health of remnant leaf oyster (Isognomon ephippium) populations in four Australian estuaries

Leaf oysters (Isognomon ephippium) are large intertidal bivalves that form shellfish reefs. They have a patchy and restricted distribution in estuaries in northern New South Wales, Australia, where the water quality is impacted by a range of anthropogenic stressors from coastal agriculture, urbanisation, industry and recreational activities, along with natural stochastic events such as flooding. Little, however, is currently known about the tolerance of leaf oysters to poor water quality. This study investigated the condition of leaf oyster populations in four estuaries, by assessing the density, size-frequency and condition index. These biological parameters were modelled against habitat water quality parameters including nutrient loads, organic and inorganic carbon, algal biomass, sedimentation and total alkalinity. The water quality assessments were replicated during dry conditions and after rain in two estuaries. Leaf oyster density, size, and body condition significantly differed among the four estuaries. Density ranged from as few as 0.04 oysters per m2 in the heavily impacted Richmond River, up to 267 oysters per m2 in the Tweed River. Overall water quality was also significantly different among the four estuaries, and significant declines in water quality were observed after rain. Distance based linear models revealed significant correlations between biological indicators of leaf oyster reef health and a range of water quality parameters. Leaf oysters with higher condition occur in locations with high dissolved oxygen and salinity levels, whereas low pH and high nutrient run-off were associated with low density and poorer oyster condition. Nevertheless, dense populations were found to persist in areas with pH below 7.9, in high turbidity (over 27 NTU) and areas dominated by fine silt. Their ability to form dense reefs on estuarine soft muddy bottom habitats with low water flow, suggests that leaf oysters could be used to complement rock oysters in future intertidal shellfish reef restoration programs.

Reproduction, body condition, age, and growth of a large sandy intertidal bivalve, Tivela stultorum

The iconic Pismo clamTivela stultorum(Mawe, 1823) once supported a thriving commercial and recreational fishery in California, but populations have declined statewide in recent decades, in part due to overfishing. To manage and restore populations, fishery managers need accurate life history information, but critical data on reproductive cycles, maturity, and growth rates is either unknown or many decades old. This project aimed to (1) determine annual reproductive cycles and body condition of Pismo clams; (2) identify environmental drivers of reproduction and body condition; (3) determine size-age relationships among clams in California; and (4) estimate growth rates. Up to 70 clams mo-1were collected from Pismo Beach, CA, for histological analysis to determine reproductive stage, measure a body condition index, and estimate ages from shells. Additional clams and shells were collected from sites north and south of Point Conception to compare growth and age at legal size between these 2 major oceanographic zones. Data suggests that reproductive timing deviates only slightly from historical records, with clams spawning later in the year than decades ago. Body condition indices correlate with reproductive stage 3 Ripe, providing an inexpensive proxy to monitor Pismo clam reproduction. Growth was faster in warmer Southern California compared to Central California, but still substantially slower than historical estimates; we estimate that Pismo clams reach the current legal size (114 mm) in 11.1 yr, several years later than previous estimates. Collectively, these data are critical to improve and guide management decisions for this once-abundant species.

Total antioxidant capacity of commercially important bivalves: A case study in Southern China

Bivalve molluscs are very nutritious and an important source of animal protein for humans. To date, bivalve farming accounts for about 15% of the mean per capita animal protein intake of approximate 1.5 billion people around the world. Because of growing consumer interest in seafood with high total antioxidant capacity (TAC), which is believed to have many beneficial effects on human health, TAC in food has become a hot topic. In this study, total antioxidant capacity of five commercially important bivalves (Amusium japonicum taiwanicum, Atrina pectinata, Perna viridis, Ruditapes philippinarum, and Scapharca kagoshimensis) was determined by ferric-reducing ability of plasma (FRAP) assay. The results showed that the total antioxidant capacity of marine bivalves was species-specific and tissue-specific. The TAC of intertidal bivalves is higher than that of subtidal bivalves, and the TAC of gills is higher than that of adductor and mantle. The findings of this study not only fill the knowledge gap of TAC of commercially important marine bivalves, but also provide consumers with useful information to identify foods (marine bivalves) that may be more beneficial to human health.

RNA-Seq analysis and WGCNA reveal dynamic molecular responses to air exposure in the hard clam Mercenaria mercenaria

Intertidal bivalves are constantly exposed to air due to daily and seasonal tidal cycles. The hard clam Mercenaria mercenaria is an economically important bivalve species and often subjected to air exposure for more than 10 days during long-distance transportation. Hard clam exhibits remarkable tolerance to air exposure. In this study, we performed RNA sequencing on hemocytes of M. mercenaria exposed to air for 0, 1, 5, 10, 20 and 30 days. The overall and dynamic molecular responses of hard clams to air exposure were revealed by different transcriptomic analysis strategies. As a result, most cytochrome P450 1A and 3A, and monocarboxylate transporter family members were up-regulated during air exposure. Additionally, the dominant molecular process in response to 5-d, 10-d, 20-d and 30-d air exposure was refolding of misfolded proteins in endoplasmic reticulum, lysosome-mediated degradation of phospholipids, protein metabolism and reorganization of cytoskeleton, and activation of anti-apoptotic process, respectively. Our results facilitated comprehensive understanding of the tolerance mechanisms of intertidal bivalves to air exposure.

Evidence of non-drilling predation by a naticid gastropod in bivalves on Camocim Beach, Ceará, northeastern Brazil

Marine gastropods of the family Naticidae are worldwide distributed and known for their unusual predatory habits. Due to their wide distribution, the naticids are worldwide studied and known like predators of intertidal bivalves. The present study demonstrates the predation of the naticid gastropod Natica marochiensis on the bivalve Donax striatus in the northeastern region of Brazil.