The sexes of sequentially hermaphroditic cupped oysters are both environmentally and genetically determined. Sex is also associated with growth or body size, females being larger than males of the same age on average. Whether sex determines size or size determines sex has not been resolved. To examine the relationship between growth and sex, 1,360 tagged individuals from six F₂ families of Pacific oyster Crassostrea gigas were reared through their second summer in Thorndyke Bay, Washington; individual live weights were recorded for 5 consecutive months, starting in June. At the last weighing, microscopic examination of gonadal tissue revealed four “sexes” in the cohort, females (43% of cohort), males (29%), hermaphrodites (2%), and sex-undetermined individuals with no gametes (26%). Live weights were fit to various sigmoidal growth curves (logistic, Gompertz, and Richards) with fixed and random parameters to account for individual variation. The best fitting curves suggested that growth of the cohort was exponential until late August, when temperatures declined and more than 70% of final weight had been gained. Individual live weights, growth-curve parameters, and growth measures were fit to general linear models with family and sex classification variables. Family-by-sex interaction was significant in many such analyses. Females were larger than males on average and appeared to attain their size advantage from superior growth characteristics rather than from initial size. Males were strikingly either like females or like the smaller sex-undetermined oysters with respect to growth comparisons within family. Sex-undetermined oysters may have been “true” males that were too small to mature as yearlings, though a size-threshold for maturation was not apparent. Genetically determined sex and family genetics appeared to control growth.

The eastern oyster, Crassostrea virginica, has been an important fishery species in the United States for hundreds of years. The emergence of population devastating diseases such as MSX and Dermo was met with the development of disease-resistant lines. Although selectively bred oysters have shown improved survival and growth under diseases in the field, it is unknown if long-term selection has altered larval fitness. In this study, the larval fitness of a selected line (DBX) was studied and compared with that of the Delaware Bay wild (Wild) population under hatchery and natural conditions with the latter using untreated seawater, 50% feeding, and declining salinity. No difference in growth was observed between DBX and Wild larvae under either condition, but DBX exhibited a higher survival under hatchery conditions (P = 0.090), whereas the Wild performed equally well under both conditions. Under natural conditions, the DBX larvae had higher survival during the first week when the salinity was high, but lower survival later under low salinity. The DBX larvae had a much higher setting success and a preference for oyster shells as substrate compared with the Wild larvae. Results of this study indicate that selective breeding has unintentionally altered larval fitness of DBX and led to adaptation to hatchery and high salinity conditions with greater setting success, and the Wild larvae have wider adaptability to different conditions. These findings suggest that careful evaluation is needed to fully assess the recruitment potential of selected stocks used in aquaculture and restoration.

Estuaries provide valuable habitat for the eastern oyster (Crassostrea virginica). Although salinity at a given location fluctuates regularly with tides, upbay and downbay salinity differences span a broad estuarine salinity gradient. Higher salinity habitats downbay support faster oyster growth, whereas lower salinities upbay act as a refuge from predation and disease but slows growth. Two experiments were performed to investigate the effect of salinity, postsettlement salinity changes, and shell morphology on juvenile oyster growth. One experiment used wild oyster spat collected from three distinct Delaware Bay salinity zones that were then transplanted into various salinity conditions in the laboratory, where growth was monitored. Transplanting into low salinity led to decreased growth compared with transplanting to higher salinity, and growth of oyster spat was overall highest for spat from the lowest salinity source. Growth did not differ among shell morphologies. A second experiment used hatchery reared larvae set in one of four different salinity conditions. Those spat were maintained in settlement salinities 22, 16, 10, and 6 for 2–3 wk postsettlement, then measured before fully factorial transfer into new salinity conditions with measurement 3 wk later. Lower final salinity treatments were associated with lower growth, lower initial salinity treatments were associated with faster final treatment growth, and final growth depended on the interaction between initial and final salinity. Therefore, in addition to the effects of acute salinity changes on growth, early postsettlement hyposalinity stress can generate compensatory juvenile oyster growth. As increased freshwater events due to climate change are expected in the Delaware Bay and regionally in the Northeast, these results indicate that nonlinear early life stress responses are important to quantify to better understand oyster stock resilience and plan management.

Increasing reliance on the use of triploid oysters to support aquaculture production relies on their generally superior growth rate and meat quality over that of diploid oysters. Reports of elevated triploid mortality have generated questions about potential trade-offs between growth and tolerance to environmental stressors. These questions are particularly relevant as climate change, coastal activities, and river management impact water salinity, temperature, nutrients, pH, and oxygen levels within key estuarine oyster growing areas. In particular, the co-occurrence of warm water temperatures and low dissolved oxygen concentration (DO) events are increasingly reported in estuaries, with potentially lethal impacts on sessile, oyster resources. To investigate potential differences in DO tolerance, diploid and triploid market-sized or seed oysters were exposed to continuous normoxia (DO > 5.0 mg L^–1), hypoxia (DO < 2.0 mg L^–1), and anoxia (DO < 0.5 mg L^–1) at 28°C and their mortalities were monitored. The hemolymph of the market-sized oysters was collected to measure cellular and biochemical changes in response to hypoxia and anoxia, whereas their valve movements were also measured. In general, about half of market-sized oysters died within about 1 wk under anoxia (LT₅₀: 5.7–8.9 days) and within about 2 wk under hypoxia (LT₅₀: 11.9–19.4 days) with diploid oysters tending to die faster than triploid oysters. Seed oysters took longer to die than market-sized oysters under both anoxia (LT₅₀: 9.5–12.1 days) and hypoxia (LT₅₀: 21.8–25.0 days) with diploid oysters (LT₅₀: 9.5–11.8 days) dying slightly faster than triploid oysters (LT₅₀: 11.8–12.1 days) under anoxia. Hemolymph pH decreased and plasma calcium and glutathione concentrations increased with decreasing DO, with values under anoxia being different than those under normoxia. Hemocyte density was also lower under anoxia than under either normoxia or hypoxia. Overall, few differences in physiological responses to hypoxia and anoxia were found between diploid and triploid oysters suggesting that ploidy (2N versus 3N) had limited effect on the tolerance and response of eastern oysters to low DO.

Predation by crustaceans and echinoderms is a significant driver of mortality for sessile invertebrates in near-shore marine ecosystems. As a response, shellfish growers use predator exclusion cages to grow their product. Oysters grown in these cages and clams in and under nets have been observed to exhibit thinner, brittle shells, which is not optimal for market, nor for those being grown for restoration purposes. Here, the nonconsumptive predator effects of several native and nonnative predators on shell morphology of Crassostrea virginica oyster spat. Juvenile (1–3 mm) seed oysters were exposed separately to chemical cues of five different predators and one nonpredator crab were investigated and compared with control (no exposure) spat. Significant effects of predator presence on the total wet weight (g) of the spat was demonstrated, with the highest increase for spat exposed to black-fingered mud crabs (Panopeus, 1.70 mg d^–1) and the biggest decreases for spat exposed to the European green crabs (Carcinus maenas—1.34 mg d^–1) and the sea stars (Asterias rubens—1.47 mg d^–1). Changes to oyster length (mm) and shell density (crushing resistance) were not significant. Implications for aquaculturists and wild bivalve populations are that growth could be negatively affected by the lack of predators on these important organisms.

The Anaskid nematode, Sulcascaris sulcata has a worldwide distribution and utilizes benthic molluscs as an intermediate host with sea turtles (Chelonioidea) serving as definitive hosts. During the spring of 2015, sea scallops (Placopecten magellanicus) harvested along the mid-Atlantic Bight (MAB) presented with rust-colored lesions on the surface of the adductor muscles. Morphological and molecular investigations determined that the lesions were caused by an infection by third- and fourth-stage larval S. sulcata. Seasonal monitoring from 2015 to 2018 delineated a stable spatial distribution of infected scallops that corresponded to a large 2013 year-class of scallops and persistent utilization of this habitat by seasonally resident loggerhead turtles. Given the life cycle and etiology of S. sulcata, the risk to human health via direct infection or allergic reaction appears to be low, however, the spatiotemporal scale of nematode-infected scallops resulted in fishery-level impacts with respect to the spatial distribution of fishing effort in response to product quality and depreciation of the value of landed scallops. The long-term trajectory of the epizootic remains unclear and continued monitoring of the spatiotemporal distribution of nematode-infected scallops is warranted as S. sulcata spatial distribution is likely dependent upon sea scallop abundance, which is currently trending toward more northerly portions of the MAB.

Warming of the Mid-Atlantic continental shelf has resulted in a range shift of the Atlantic surfclam, Spisula solidissima, north and offshore into waters still occupied by ocean quahogs (Arctica islandica). An ecotone, a boundary transitioning between neighboring ecological systems over a wide range of space and time, now exists over much of the offshore range of the surfclam in which surfclams and ocean quahogs co-occur. Regulations prohibit fishers from landing both species in the same catch, limiting fishing to locations where the target species can be sorted on deck. An at-sea survey sampling 50+ stations in the overlap region was conducted in September 2021 with the purpose of mapping fishable concentrations of surfclams and ocean quahogs. Size frequency and density data of both species were assessed along with environmental parameters. Species overlap between surfclams and ocean quahogs was most prominent in the 40- to 55-m depth range. Density of surfclams shifted within this depth from surfclam dominant in less than 40 m to ocean quahog dominant in greater than 60 m. Atlantic surfclam length increased with increasing summer bottom water temperature, whereas densities remained stable, indicative of proportionately larger but fewer animals in warmer inshore waters. Ocean quahog size metrics and densities, on the other hand, remain relatively unresponsive to temperature and invading Atlantic surfclam populations and instead increase in size with higher latitude. Large ocean quahogs, in particular, exhibit a distinct correlation with high latitude but fail to do so with other environmental variables. This analysis emphasizes the potential for economic disruption of fisheries as climate change pushes surfclams further into the range of the ocean quahog and highlights the need for regulatory changes to allow mixed catches and landings. The study also emphasizes the importance of the relative rates of transgression and regression of range boundaries by abutting faunas in determining the degree of influence of the ecotone between them on the benthic community structure of the continental shelf.

Organisms increase in size over time (age) due to excess assimilation over metabolic (respiration) energy demands. Most organisms reach a maximum size with increasing age as gain and loss balance. The von Bertalanffy length-at-age relationship, which is commonly used in fishery assessment calculations, imposes such a maximum size. However, some fished species, such as ocean quahogs, Arctica islandica, are long lived and continue to grow at old age. The Tanaka age-at-length relationship has continued growth at old age, but is rarely used in stock assessment models. A modified form of the von Bertalanffy model is presented, which mimics the continued growth at old age of the Tanaka model by allowing the growth parameter (K) to decline with age. This form is suitable for inclusion in stock assessment models based on von Bertalanffy. The proposed model matches Tanaka curves with precision appropriate for the scatter of data used to fit the curves. The observations of ocean quahog length at age and growth rate from New Jersey and Georges Bank demonstrate the ability of the modified von Bertalanffy relationship to represent continued growth at old age for this fished species. Simulated data generated with continued growth at old age were fit with the Stock Synthesis model (SS3). Results comparing traditional and modified growth relationships showed that the original von Bertalanffy model can reasonably approximate modest nonasymptotic growth as long as the number of observations is sufficient to constrain the parameter values.

Since 1898, the Pacific razor clam, Siliqua patula has represented an important resource for commercial and recreational diggers and has been an important source of economic revenue to coastal communities in the Pacific Northwest from central California to southern Alaska. In 1996, Washington State adopted the Pumped Area Method as the preferred method to accurately assess populations of razor clams on coastal beaches. The Pumped Area Method utilizes a water pump and a series of hoses to draw water out of the surf to liquefy the clam bed exposing clams so they can be measured and recorded. This method relies on a fixed stratified random sampling of transects across all managed beaches to produce a robust estimate of the total population of clams. The Pumped Area Method has been adopted by state and tribal management agencies along the west coast to determine the total allowable catch in each management area but never been formally described. This method in conjunction with a biweekly sampling of toxic algae abundance supports the sustainable harvest of razor clams, providing up to 40 million dollars annually in economic income to the state of Washington for the last 25 y.

Florida is one of the largest exporters of aquarium ornamental species in the world, but trade is expanding to include harvest of herbivorous invertebrates that play important ecological roles in nature, such as grazing algae from seagrass and corals. Here, stable isotope sclerochronology is used to document life history traits of two of the most intensely harvested herbivorous gastropod species in Florida, the turbinids Lithopoma americanum and Turbo castanea. Such information is critical to assessing whether current harvest intensities are sustainable. Populations of L. americanum and T. castanea in Florida consist of rapidly maturing individuals that reach maximum sizes within 2 y and 1 y, respectively. Rapid maturation should allow these populations to recover rapidly from intense harvest, but short-lived species are also intrinsically susceptible to population collapse from recruitment failure, complicating effective management of the fishery. In addition, the short lifespans of these turbinids suggest that hobbyists may purchase replacement animals frequently, increasing fisheries pressure on natural ecosystems.

Accurate distribution and density data of endangered marine species may be complicated by artifacts from exploitation, survey design, and general difficulty in accessing subtidal habitats. Occasional review of survey data may help restructure survey efforts to improve conservation outcomes. The white abalone (Haliotis sorenseni) is a marine gastropod listed under the Endangered Species Act thought to primarily inhabit depths beyond conventional scientific SCUBA limits (30–60 m) in the southern California Channel Islands. This study reviews surveys at four Channel Islands and four locations along the southern California mainland coast within SCUBA depth ranges and conducts a simulation comparison of the larger survey design used for this study with the standard transect approach presently common in the region. White abalone density was greater along the mainland, particularly in Point Loma and La Jolla, than the Channel Islands, where no live white abalone were recorded. The larger survey approach was found to be more effective at finding simulated white abalone, beyond the expected difference in areal coverage alone. These results show that surveys within SCUBA limits are an effective way to monitor H. sorenseni and that impacts from overfishing on the Channel Islands may make sections of the mainland coast one of the last refuges of white abalone. The greater efficiency of larger surveys can complement standard transect approaches to improve abalone monitoring at sites of interest. Both results can be applied to the immediate conservation of white abalone by improving site selection and monitoring approaches to active restoration efforts.

The Atlantic brief squid, Lolliguncula brevis, is a euryhaline cephalopod that inhabits shallow, continental shelf habitats from Argentina to the Bay of Fundy. In the southeastern United States, brief squid can account for a considerable portion of the estuarine animal biomass and are an important component of the diets of species with high priority for management and conservation. Historical data from South Carolina Department of Natural Resources suggest that brief squid exhibit spatially and temporally variable size-frequency distributions within the Charleston Harbor estuary. Prior to this study, however, detailed life history information for this species was lacking in the region. Samples of brief squid were collected monthly at four stations along a salinity gradient within the Charleston Harbor estuary in 2019 to investigate temporal and spatial patterns of abundance, sex, size, and maturity. Season and station were significantly related to brief squid abundance, which was greater for all sexes in spring, summer, and fall than in winter. Catches of brief squid were dominated by immature squid compared with mature squid. Excluding sexually indistinct squid, and across all seasons, significantly more males were collected than females. Mean brief squid size tended to be larger in May than in several other months of the year, largely due to the lower abundance of small squid in that month. Logistic regression analyses indicated that brief squid size-at-maturity occurred at 50.2 mm for males and 59.2 mm for females. The presence of both small and large brief squid throughout the year at all stations supports a pattern of overlapping cohorts, whereas the continual presence of immature brief squid at all stations suggests asynchronous recruitment. This study provides valuable life history information that can be used to support the conservation and management of organisms that are either prey or predators of brief squid within the Charleston Harbor estuary. Further research over multiple years and within other estuaries in the Georgia Bight is needed, however, to determine how the life history patterns observed in this study apply more broadly across the region.

Decapod iridescent virus 1 (DIV1), also known as shrimp hemocyte iridescent virus or Cherax quadricarinatus iridovirus, has received extensive attention in recent years due to its highly contagious and lethal properties in crustaceans. In 2019, the Executive Committee of the International Committee on Taxonomy of Viruses approved DIV1 as a new species of the new genus Decapodiridovirus in the family Iridoviridae. To gain a more comprehensive understanding of DIV1, this review summarizes recent advances in DIV1 research, including classification, detection techniques, clinical symptoms, infection mechanisms, and host immune responses. A deeper understanding of the interaction between DIV1 and the host has potentially important implications for developing effective antiDIV1 strategies.

Emerging infectious diseases in marine systems threaten food security and ecosystem function. Experiments to determine drivers of transmission and mortality from emerging pathogens require a reliable supply of disease-free animals. Imperfect detection of subclinical, latent, and early stage infections, however, necessitates effective treatments to remove infection from animals with unknown infection status. In this study, a procedure utilizing elevated temperatures and over-the-counter parasiticides to remove Hyalophysa lynni was developed. The apostome ciliate H. lynni is responsible for shrimp black gill (sBG) disease in commercially important southeastern shrimp fishery species, including Litopenaeus setiferus (white shrimp). Following a series of pilot studies to determine parasiticides combination and dosage, L. setiferus of unknown infection status were exposed to either 20°C or 30°C artificial seawater, and a parasiticide cocktail of metronidazole (3.15 mg L–1) and Cu+2 (0.5 mg L–1) or a medication-free control for 14 days in a fully crossed experimental design. All treatments, except for the 20°C without medications treatment, significantly reduced pathogen prevalence. The 30°C artificial seawater with parasiticide treatment resulted in complete curing of the experimental population, but shrimp mortality in this treatment was high (50%). This high mortality may have contributed to the low parasite prevalence found in this treatment by differentially culling infected individuals. If this is the case, the parasiticides may lower the parasite prevalence both by curing infections and heightening stress and subsequent mortality of diseased individuals. Although this procedure was developed to produce H. lynni-free shrimp to facilitate experimental studies of sBG disease, it is likely that this methodology would effectively produce specific-pathogen-free individuals in other crustacean species.

Sea cucumbers are important components of marine ecosystems and also highly valued commodities in Asian markets because of their use in oriental cuisine and traditional medicine. The increasing demand for sea cucumbers has elicited intense worldwide capture and many species are currently considered vulnerable or threatened due to overexploitation. The coast of Santa Catarina State (South Brazil) is the distribution limit of several tropical species in the Western South Atlantic, but little is known about the sea cucumber species occurring in this region. This study aimed to identify the holothuroids occurring in the littoral of Santa Catarina State and to survey their abundance and distribution along the coast. Visual and tactile inspections were carried out following transects in the intertidal zone of 11 locations and subtidal surveys were carried out by diving in two sites. The surveys indicated the occurrence of three species: Parathyone braziliensis in the intertidal zone, Holothuria (Halodeima) grisea in the intertidal as well as in the sublittoral, and Isostichopus badionotus in the sublittoral. The most abundant species was H. (H.) grisea, which occurred in several sites along the coast, up to Lat. 28° 01′ 07.67″ S, its likely southern limit of distribution. The species I. badionotus was for the first time recorded to occur on the continental coast of the State, expanding its area of distribution. This study registers for the first time the occurrence of P. braziliensis in southern Brazil, expanding its limit of geographic distribution.

Many authors have tested a large number of tagging methodologies on sea urchins, either with the aim to study the growth of urchins, their movement patterns, the dynamics of their populations, or their ecology and development in the natural environment. Different types of markings, both external and internal, have been used for the individual identification of sea urchins since the year 1935. Since the year 1969, marking techniques based on different chemical substances were also implemented, either by immersion in fluorochrome baths or by injecting these substances directly into the sea urchin. There is a clear need to collect all the existing information to date related to the marking methodologies for sea urchins, to establish the most appropriate marking methodology for each species of sea urchin, depending on the objective and duration of the study to be performed.

This report presents for the first time a complete review of tagging methodologies used until the date in different species of sea urchins, from physical methods, such as the use of Passive Integrated Transponder (PIT) Tags, Anchor tags, and so on, to chemical ones, in which different fluorochromes are used that adhere to the calcified structures of the sea urchin and are subsequently detected using a fluorescence microscope.

We also analyzed the effectiveness of the methods used in each case, comparing the survival rate, the tag retention rate, or the recapture rate of tagged urchins obtained with each tagging methodology.

The evolution of the physical tags for sea urchins should be oriented toward the development of more durable markings over time, which allow marking urchins of smaller diameter and which in turn present a higher retention rate in the long term, both in captivity conditions and in the natural environment. The chemical tags should be aimed at reducing costs through the development of methods, where the mark can be visualized without the need of fluorescence microscopes, the development of methods in which the dyes can be reused, and finally to the development of techniques that allow to visualize the fluorochrome marks externally, without the need to sacrifice the urchin for the mark detection.