Three ceramides with intriguing structural features, bathymodiolamides C (1), D (2), and E (3), were isolated from the deep-sea hydrothermal vent invertebrate mussel Bathymodiolus azoricus that inhabits vent environments along the Mid-Atlantic Ridge. The molecular structures of these compounds were elucidated using a combination of Nuclear Magnetic Resonance spectroscopy, mass spectrometry, and chemical degradation. Biological activities were assessed by Lactate Dehydrogenase assay for necrosis induction and the patented ApopScreen cell-based screen for apoptosis-induction and potential anticancer activity. This represents a second report of ceramide natural products from B. azoricus.

Marine bivalves are exposed to several environmental stressors depending on fluctuations in abiotic factors (pollutants, salinity, and temperature) and biotic factors, including ascidian biofouling. Increased seawater temperature may lead to oxidative stress in marine animals, whereas the additional burden presented by ascidian biofouling narrows their thermal window and can cause a sharper decline in shellfish health, with subsequent effects on shellfish aquaculture. The aim of the present study was to investigate the role of seawater temperature variations in the severity of the stress caused by ascidian biofouling to Mytilus galloprovincialis cell machinery, particularly in the antioxidant defense system, and the apoptotic and autophagic pathways. Fouled and nonfouled mussels were seasonally collected, and several key indicators of the previously mentioned cellular processes were determined in their mantle and posterior adductor muscle tissues. Results indicate that ascidian biofouling increases hypoxic conditions and oxidative stress, subsequently triggering cell death pathways in mussels. Although the stress caused by ascidians may be the consequence of both reduced feeding and oxygen consumption, it affects the mussels to a greater extent than seasonality. The induced stress by biofouling, along with elevated water temperatures in summer, may severely harm mussel physiology and fitness, adversely affecting aquaculture sustainability.

Salinity fluctuations promote adverse effects on the immunity of marine bivalves; however, sometimes experimental data are controversial. In the present work, we evaluated in vivo effects of short-time salinity changes on hemocyte functions of Mediterranean mussel, Mytilus galloprovincialis. Mussels were acclimated to hyposaline (6, 10, 14) and hypersaline (24,30) conditions and exposed to altered salinity for 2 days. Then hemolymph cellular composition, hemocyte immune (intracellular reactive oxygen species (ROS) production, phagocytic activity), and functional parameters (morphology, mitochondrial membrane potential) were measured using flow cytometry and fluorescent microscopy. Salinity fluctuations led to an increase of ROS production by hemocytes in all experimental groups. Increased ROS levels were accompanied with elevated mitochondrial membrane potential for all treatments except salinity 30, where the parameter decreased significantly. Salinity stress (all experimental groups) inhibited phagocytosis in agranulocytes, whereas stimulated phagocytic activity of granulocytes at salinity 14 and 24 indicating that moderate salinity fluctuations may cause stimulating effect on immunocytes of bivalves. Hypersaline and hyposaline treatments did not affect hemocyte morphology. These results indicate that hemocytes likely possess physiological mechanisms that restore initial cellular volume following hypoosmotic swelling/hyperosmotic shrinkage. Salinity stress affects hemocyte functionality of bivalves with varying intensity.

There is increasing concern on how future climate change (CC) will affect fish and shellfish populations. The European Union funded the Climate change and European aquatic RESources (CERES) consortium to collaborate with industry and policy stakeholders to test CC scenarios through 24 “storylines” linked to specific regional fisheries or aquaculture activities. For this study, the focus is on “storyline 7” related to offshore longline aquaculture for Mediterranean (Med) mussel (Mytilus galloprovincialis, Lamarck, 1819) along the Atlantic coast at Sagres, Southern Portugal. CERES has compared two greenhouse gas emission scenarios in terms of Representative Concentration Pathways (RCP) 4.5 and 8.5 W m^–2 for projected mean sea surface temperature (SST) and mean net primary production (PP) comparing the period 2000 to 2019 to the period 2080 to 2099. With regard to SST in the Algarve, the prediction is for an increase of up to 1°C and under RCP 4.5 and up to 2°C under RCP 8.5 by the end of the century, while the projected changes for net PP are much more variable, with a trend for a slight increase for both RCP 4.5 and 8.5. Some of the key research activities included an experimental study testing the combined effects of temperature (3°C, 8°C, 15°C, 20°C, 25°C) and chlorophyll (2.10 µg^–1), the data from which was used for a WinShell mass balance model based on an individual Med mussel grown offshore at Sagres and then incorporated into the local-scale Farm Aquaculture Resource Management model to provide data for projecting climate-driven changes on production potential. Mussel weight at harvest and production yield at Sagres are similar under both emission scenarios, RCP 4.5 and 8.5 at periodic time periods between the years 2000 and 2099. The Med mussel was able to adapt to SST up to 25°C provided the PP was reasonable. A core activity of CERES is engagement with stakeholders, with the help of bow-tie analysis to reflect stakeholder concerns about the current and future factors affecting Med mussel production, as well as the development of a probabilistic Bayesian Belief Network model linking biological projections with economic consequences and policy measures to test whether current management systems can adapt to identified risks under CERES scenarios. Initial interactions with stakeholders showed that they were much more concerned with day-to-day issues, including failure of mussel spat recruitment, reduced mussel condition, and periodic closures due to harmful algal blooms, rather than any hypothetical future problems arising from CC. Nonetheless, there was much more interest when potential scenarios arising from CC were presented. The Med mussel does seem to be better adapted to higher SST compared with the blue mussel (Mytilus edulis).

The quality of mabé pearls from pearl oysters, Pteria sterna, produced in the Chone River Estuary, Ecuador, was evaluated. Adult oysters (70–75 mm total length) were grafted with half-pearl nuclei and then maintained in suspended culture conditions in lantern nets at a density of 20 organisms/level. Results showed that the culture conditions generated a great negative influence on the development of nucleated organisms, which resulted in high mortalities and little pearl production. Despite the high mortality, the oysters that managed to survive the second month (22%), produced mabé pearls with nacre thickness deposited on the top of the implanted nucleus close to 0.70 mm, the majority (>25%) being of intermediate quality (A and B), according to classic classification criteria (size, luster, impurities, roundness), followed by noncommercial pearls (10%–27%) and 15% high-AA quality mabé pearls. A small fraction was considered as gems (<5%). The mabé pearl production structure is like that produced in P. sterna cultivated in marine environments. The results show that in the Estuary of the Chone River, mabé pearls can be produced in 2 mo; however, production can be low due to high mortalities. It is recommended to carry out further research to minimize mortality and establish greater production feasibility.

Oyster reefs are a primary source of calcium carbonate in most estuaries and the habitat complexity provided by these reefs supports a diversity of estuarine life. The available surface area of hard substrate on an oyster reef is critical for population maintenance, as this substrate provides habitat for the settlement of new oyster recruits. On natural reefs, the primary substrates available for settlement by spat include live oysters, boxes (dead articulated valves), and cultch (single oyster shells and shell fragments). Data from a long-term oyster monitoring program from February 2016 to October 2020 were used to generate a monthly time series of the percent of total carbonate weight contributed by live oysters, boxes, and cultch at four reefs in the Mississippi Sound. These percentages vary spatially and temporally. When reefs were healthy, live oysters dominated the total carbonate. During the study period, two mass mortality events occurred. Following the 2016 mortality event, the substrate contributing the majority of the carbonate shifted from live oysters to cultch at all reefs sampled. Three reefs exhibited a modest population recovery following the mortality event only to be impacted by a second, more severe mass mortality event in 2019. Boxes usually had the highest number of spat per gram carbonate at all reefs. The potential surface area (PSA) of each substrate type was calculated by comparing the available surface area of each substrate type and the number of spat that settled on each substrate. Correction factors were generated to account for larval settlement preferences and used to either debit or credit the PSA to calculate effective surface areas (ESA) for each substrate type. Cultch offered the highest ESA at Pass Christian, and cultch ESA was higher than box ESA at Henderson Point and Between Bridges reefs. At Bay St. Louis, box ESA was twice that of cultch. These results suggest cultch and boxes are more valuable settlement substrates than live oysters in this region under the conditions present during the survey time frame, which was characterized by low oyster abundance and aperiodic mass mortality. The unbalanced ESA, in which live oyster ESA is underrepresented, represents an unhealthy condition and demonstrates that a critical period exists for reef recovery after mass mortality in which the timely coincidence of increased box ESA and larval availability is essential for rapid recovery from mass mortality.

Disseminated neoplasia is reported for the first time in Ameghinomya antiqua (Veneridae) from Chile on the southeastern Pacific coast. A total of 710 clams were collected in winter 2019 and summer 2021 from five sites in three regions: Coquimbo, Biobio, and Los Lagos; all clams were processed by histology. The disease was only detected in clams from the Biobío region. It was characterized by the presence of numerous neoplastic cells with enlarged nuclei and high nuclear to cytoplasmic volume ratios and the almost absence of normal hemocytes. The prevalence did not vary between seasons (7% in winter and 9% in summer).

The ontogenetic changes of the scallop Patinopecten yessoensis from Dalian, China, were studied during four stages (3, 6, 12, and 24 mo) using a geometric morphometric method and cross-validation method for evaluating the utility of the classification. The results showed that they exhibited characteristically different ontogenetic trajectories within a space defined by test size and shell shape. Landmark and semilandmark analyses were applied to successfully determine the stage of the individuals with approximately 89.04% accuracy. Moreover, each stage had a typical shell shape. The distinction of these patterns was assigned to the circularity and symmetry of the disc and the symmetry of the auricles: the 3 mo shells had a circular disc and asymmetrical auricles, and the 6 and 12 mo shells showed a more elongated disc and more symmetrical auricles, whereas the 24 mo shells showed an elongated disc and relatively small, symmetrical auricles. The ontogenetic shell form changes (size + shape) of P. yessoensis reflected the life history characteristics, which could potentially be used for age stage identification. The results provide a reference for determining the growth stage of P. yessoensis during fisheries and aquaculture management.

The purple hinged rock scallop, Crassadoma gigantea (Gray 1825), is a species of interest for commercial-scale aquaculture in its native range, along the Pacific coast of North America from Baja California, Mexico to southeastern Alaska. One serious, unresolved issue, however, is the lack of information on uptake, retention, and depuration of algal biotoxins in this species. It is known that rock scallops can retain high levels of paralytic shellfish toxins (PST), including saxitoxin and derivatives, within its tissues including the adductor muscle. Paralytic shellfish toxins can pose serious public health risks, including paralytic shellfish poisoning (PSP), which can be lethal in humans. Diarrhetic shellfish toxins (DST) produced by algal species within the genus Dinophysis spp. is another suite of marine biotoxins monitored by public health agencies, known to cause diarrhetic shellfish poisoning (DSP) in humans. This is the first study to investigate dynamics of Dinophysis spp., and DST in the rock scallop. The present study examined uptake, retention, and depuration of two common toxic algal species and associated biotoxins in Puget Sound, WA: Alexandrium catenella (PST) and Dinophysis spp. (DST), through multiyear field exposures and controlled laboratory studies. Assessment of PST in rock scallop tissues by receptor binding assay from field and laboratory studies revealed very high and persistent levels of PST in visceral tissue and also PST in adductor muscle tissue beyond the FDA limit (80 µg STX equivalents 100 g^–1 shellfish tissue) for safe shellfish consumption. An estimate of total depuration time of PST in rock scallop viscera was inconclusive, indicating potentially long depuration times for this species. Toxicity levels varied among individuals of the same cohort, size class, collection time, and location for both visceral and adductor muscle tissues. Laboratory results showed PST levels beyond the FDA limit within adductor muscle tissue during a 6-wk depuration period, indicating a shucked, adductor-only product for this species will require careful testing and management to ensure rock scallops are safe for consumption. More research is needed to decouple the complex interactions of Dinophysis spp., DST, water quality, and rock scallop physiology to inform shellfish managers and public health agencies reliably.

The population biology of the limpet Cellana grata in the Nanji Islands region was studied to facilitate its protection. In 2021, monthly collections of C. grata (2,624 individuals) were taken from the Nanji Islands in Zhejiang Province, China. Hierarchical cluster, regression, and path analysis were used to analyze the group composition and growth. The results showed that (1) the meat:shell ratio was highest in May, lowest in October, and the breeding season was in June. (2) The population was divided into three age groups (0–12, 13–24, and >24 mo), accounting for 33.77%, 57.96%, and 8.27% of the total population, respectively. The shell lengths were less than 25 mm (first age group), 26–34 mm (second group), and greater than 34 mm (third group), and a supplementary population (shell length 22 mm) appeared in June. (3) Growth rates were high from March to May (absolute shell growth rate:1.24, 1.45, and 0.85 mm) and September to October (0.88, 1.43 mm), and low from June to July (0.46, 0.65 mm) and November to December (0.73, 0.36 mm). Growth rates were moderate in other months (0.72, 0.74 mm). (4) The optimal regression equation between total mass (Y ) and morphological parameters (sample shell length, X ₁; shell width, X ₂; shell height, X ₃) was Y = –8.325 + 0.174X ₁ + 0.218X ₂ + 0.219X ₃ (R ² = 0.853). The effects of morphological traits on body weight were also analyzed.

In this work, an inadvertent discovery revealed that the prolonged starvation of brooding Crepidula fornicata L. caused the irreversible shell loss of the offspring. This study hypothesized that the shell loss resulted from the hypoxia suffered by the embryos during the incubation period, given that if a brooding snail is starved, the pumping rate is reduced, producing a drop in oxygen diffusion through the egg capsule walls, and thus hypoxic conditions in the intracapsular environment occur. As a result, the embryos trapped within the capsules suffer hypoxia and are forced to shift into anaerobic metabolism to survive, producing CaCO₃ destined for the shell to be alternatively used as a pH buffer during metabolic acidosis. Under these sublethal conditions, embryos continue their development until hatching. The resulting shell-less larvae continue their free-swimming period and undergo metamorphosis to give way to crawling radula-feeder juveniles. Several experiments were carried out to test this hypothesis. First, the reduction in the pumping rate of starved snails (13.3±0.3mL h^–1) was confirmed compared with fed snails (31.6±0.3mL h^–1). The calcium content of larvae from egg capsules from fed and starved snails was 537.4 and 125.4 ngCa µgdtw^–1, respectively. To simulate conditions inside the mantle cavity of the mother, groups of detached egg capsules were exposed for 24 days to different water flows in open-flow glass chambers. The results indicated egg capsule survival of 93% and 83% at flow rates of 197 and 103mL h^–1, respectively. Total capsule mortality was found on days 12 and 15, at 16 and 811mL h^–1, respectively, indicating a flow range for the normal development of the encapsulated embryos and larvae. Morphological features of embryos, larvae, and juveniles from fed and starved brooding snails were compared using a scanning electron microscope. The results supported the original hypothesis that starvation of adult egg-bearing C. fornicata results in irreversible shell loss in offspring.

The octopus fishery in the state of Yucatan is one of the most important in Mexico and landings have doubled over the past decade causing an increase in the demand for crabs used as bait. Data on bait composition and their harvest are limited even though its economic and ecological impact could be considerable. DNA barcoding of the 16S gene was used to identify the species of crustaceans in 93 samples of bait collected from 12 localities from Yucatan during August to October 2022. A total of nine species of crustaceans were identified, from which the mangrove crab Ucides cordatus was the most frequent (61%), followed by the longnose spider crab (Libinia dubia, 14%), and the Caribbean spiny lobster (Panulirus argus, 8%). The use of bait shows strong spatial patterns, including the local exploitation of some species and the import of bait from various geographical sources from other adjacent Mexican states to meet the demand. Although some sustainable practices were documented, such as using the discarded cephalotorax from the fishery of Caribbean spiny lobster, at least one species banned as bait by fisheries regulations (the stone crab Menippe mercenaria) was also identified. The American horseshoe crab (Limulus polyphemus), a protected species of national and international conservation concern, was absent in this samples. This study suggests that bait harvest for the octopus fishery could potentially impact both local and distant crab populations, and highlights the need to create and improve existing regulations for bait harvest that need to be built and clearly communicated within the fishing communities to improve the sustainability of the fishery.

The future of American lobster (Homarus americanus; H. Milne Edwards, 1837) habitat has been extensively studied in the Gulf of Maine and Georges Bank regions, but studies quantifying spatiotemporal changes to suitable habitat in Southern New England (SNE) regions remain sparse. The American lobster stock assessment for SNE is conducted separately from the northern stock because of negligible migration and recruitment sharing between them. This fact, coupled with the assumption of spatial nonstationarity between the two stocks when it comes to environmental preferences, suggests that analyses of suitable habitat must be conducted for each stock region independently. This study employs the use of a previously developed habitat suitability index model for American lobster to map historical and forecasted habitat in both the Gulf of Maine and SNE stock regions so that comparisons between long-term forecasts can be accurately made. The suitability indices generated in this study support the hypothesis of environmental nonstationarity between the stocks, with lobster in SNE preferring significantly different environments than their northern counterparts. In the coming decades, the Gulf of Maine lobster fishery may see changes in lobster migration timing as spring suitability decreases and fall suitability rises, whereas the SNE fishery will most likely see the continued use of northern waters by lobsters as more southern waters become less suitable. The rate of change in SNE remains smaller than in the Gulf of Maine owing to the lesser rate of warming observed.

Bivalve mollusc production has been proposed as a method to reduce carbon emissions as (1) a low-emission protein source, and (2) via carbon stored in their shells. Numerous studies have examined the fate of carbon in bivalve production, estimated carbon sequestration rates, and their role in a carbon economy. To address the fate of shell carbon for the Northwest Atlantic, stored oceanic carbon equivalents (Eq), released CO₂via calcification, and hypothetical carbon credit value ($24 tCO₂), for both aquacultured and wild-captured bivalves for New England and Canadian Provinces on the Atlantic between 2016 and 2020 were estimated. Bivalve shells do not sequester atmospheric CO₂, instead storing oceanic CO₂ Eq and cannot be directly included in a carbon sequestration scheme. In the present study, total annual estimates of stored oceanic CO₂ Eq were approximately 202,253 and 363,243 tons, with concurrent releases of approximately 121,255 and 217,771 tons of CO₂ to the atmosphere, of which only 4% and 8% were from aquaculture production in Canada and the United States, respectively. Even if bivalve shells sequestered atmospheric CO₂, current shellfish production levels are inconsequential with regard to current anthropogenic greenhouse gas (GHG) emissions. Stored oceanic carbon Eq for bivalve aquaculture is equivalent to 0.001% and 0.0005% of Canadian and US annual anthropogenic CO₂ emissions, whereas wild-capture would store 0.028% and 0.005% of Canadian and US emission, respectively. Bivalve shell will not solve climate change, but the expansion of bivalve production provides a protein source with the lowest GHG emissions, which provides a multitude of environmental services.