Telomeres are evolutionarily conserved sequences capping the ends of linear eukaryotic chromosomes that usually shorten at each cell division, as well as under stressful living conditions. For this reason, telomere length (TL) has been considered as a proxy of age and stress for decades. Globally, most ecological and biology researches have used TL to assess the impact of specific life history traits on organisms life expectancies and persistence of populations. Nevertheless, to our knowledge, ecological studies that consider TL as an approximation of temporal cohorts are rare. In many population monitoring studies, however, knowledge about temporal cohorts are lacking, although they would provide comprehensive information on the natural processes underlying population dynamics. With this in mind, a quantitative PCR approach was used to measure the relative length of telomere sequences of DNA extracted from Paracentrotus lividus sea urchin. The species undergoes intensive harvesting, and some populations are under surveillance in the Mediterranean basin. The results showed that P. lividus experiences a shortening of telomeres with age, suggesting that according to this hypothesis, TL would probably be a relevant biomarker, which could reveal population differences based on their demographic structure, and differential susceptibility to pollution according to size. Future studies are still needed to define the accuracy of TL in detecting specific temporal cohorts in this species and to determine whether the TL should be considered locally in population surveillance studies.

The softshell Mya arenaria is an ecologically and commercially important bivalve mollusc that develops a fatal cancer known as disseminated neoplasia or hemocyte leukemia. This cancer, like many human cancers, involves the master control gene of apoptosis, p53. This gene is also known to interact with retrotransposons, and a growing body of evidence suggests that p53 actually controls retrotransposon expression and subsequently oncogenesis. The recent description of a retrotransposon (i.e., Steamer) in adult M. arenaria and its potential involvement in the oncogenesis of hemocyte leukemia has been suggested. Juvenile clams, previously shown not to develop hemocyte leukemia, were exposed to climate-related changes in seawater temperature and pH predicted for the year 2100. All juvenile softshells do express the retrotransposon Steamer. When juvenile clams are exposed to predicted climate-related changes in temperature and pH in the Gulf of Maine, it significantly induces Steamer expression, specifically in treatments where clams were exposed to low pH. For juvenile individuals of M. arenaria and potentially other bivalves, Steamer may be a candidate biomarker for exposure to ocean acidification conditions.

Common-pool resources such as public oyster grounds are especially vulnerable to overexploitation and habitat loss. Like those elsewhere, oyster populations and habitat of Louisiana public grounds are in decline. To maintain reef habitat and increase oyster abundance, a sustainable harvest model is applied, which allows harvest above that required to maintain reef cultch stasis. The model is restrained to promote shell gain by limiting fishing by area, type (sack versus seed), effort, and season. Harvest quotas and cultch removal rates derived from shell-budget–based modeling are a foundation for sustainable management of public oyster resources.

Pacific abalone (Haliotis discus hannai) is an economically important species of sea snails found in China. Live abalones sold in domestic markets are sealed in insulated containers for transportation over extended periods of time (6–24 h), during which this species may experience stressful conditions and spoil. This study assessed the survival rate and weight loss rate (WLR) of abalone under various treatments to determine the optimal packaging transport conditions. Specifically, temperature, supplemental humidity and oxygen, and air exposure during simulated live transport were investigated. Results revealed that the survival rate increased significantly after cold-water shock and humidity control, whereas oxygen supplements did not have a significant effect. In addition, WLR significantly increased over time (P < 0.05). An additional experiment was conducted to investigate the stress response caused by air exposure. Hemocyte parameters, including total hemocyte count (THC), hemocyte mortality, and reactive oxygen species (ROS), were estimated for 2, 6, 12, 24, and 30 h after air exposure at different temperatures. Results revealed that THC significantly decreased after 30 h of air exposure at 5 and 10°C, and after 24 h of air exposure at 20°C. Hemocyte mortality and ROS significantly increased, peaking after 30 h at 5 and 10°C, followed by a gradual decrease over the subsequent 24 h recovery period. THC and ROS levels remained higher than the control levels by the end of the recovery period. The parameters investigated in this study could serve as indicators for the effects on the functional immune response and physiological stress of abalone during live transportation.

Accurate estimates of fecundity and spawn timing are essential to fisheries management but can be difficult to obtain in nonaggregating broadcast-spawning species such as the commercially harvested sea cucumber Parastichopus californicus. Individuals of P. californicus collected from Southeast Alaska (SEAK) over 3 y were examined to determine the timing of spawning based on seasonal variations in gonad indices (GI). Gonad indices measured at different time points in the annual reproductive cycle were compared with gonad lipid content and egg development to validate GI as an indicator of gonad maturation. Fecundity was estimated as the total number of eggs and as the number of viable eggs produced in both live-spawned and strip-spawned animals. Results suggest spawning may occur slightly earlier than previously reported in British Columbia, Canada, where fecundity was about two times higher than in SEAK. Seasonal changes in gonad total lipid and maturation stage were recorded. Gonad index was moderately correlated with both gonad lipid content and maturation stage. Estimates of total fecundity and viable eggs based on live spawning did not significantly differ among the 3 y sampled. Live spawning yielded comparable estimates of total fecundity and viable eggs per gram female wet weight compared with strip spawning. These findings inform aquaculture efforts and management of the commercially harvested SEAK population of P. californicus.

The blue crab Callinectes sapidus Rathbun has been the subject of scientific investigation for more than 100 years. The crab is a key predator in shallow estuarine and coastal environments, and supports a large commercial fishery along the Atlantic and Gulf Coasts of the United States. Much of the initial research on C. sapidus was purely descriptive and provided only a patchwork perspective on the natural history of the crab. This is in contrast to more modern work that has defined a clear, interrelated series of processes that underlie the early life history of the species. The intent of the present review was to discuss contemporary understanding of the early life history of blue crabs in the context of a coherent time line of development. The review begins with a short section on general aspects of the life history, which provides a background for the overall discussion. This is followed by a segment on courtship and mating, with particular emphasis on chemical communication between mating pairs. Three subsequent sections then deal, respectively, with spawning migrations within the estuary, larval release in the adjacent coastal ocean, and transport of larvae on the inner continental shelf. A following segment, describes settlement of the larvae in the lower estuary and eventual transport of early juvenile stages to estuarine nursery areas. The final section provides a summary and conclusions. Points of emphasis in the review include the following: (1) the role of pheromones in courtship and mating; (2) the discovery of two distinct phases in the spawning migration; (3) the importance of chemical cues in assuring synchronized hatching of eggs; (4) the predominant effect of wind- and buoyancy-driven processes in controlling larval transport in the coastal ocean; (5) the development of mathematical models that allow critical analysis of transport processes; and (6) the combined physical and behavioral processes that facilitate transport of megalopa larvae from the estuarine mouth to nursery habitat in the lower estuary.

Fluid and its associated mucus from the pallial (mantle) cavity of the ribbed mussel Geukensia demissa (Dwillyn) from Black Rock Harbor, Bridgeport, CT, inhibited the growth of both Gram-positive (Staphylococcus aureus) and Gramnegative (Escherichia coli) bacteria in antimicrobial assays. A significant reduction in size after 24 h was noted in E. coli grown in the presence of ribbed mussel fluid. Mussel-soluble lysozyme levels in the pallial cavity fluid averaged 0.019 + 0.018 relative fluorescence units/mg protein, and no seasonal pattern of lysozyme activity was found (P = 0.522). During the course of the study, copper concentrations ranged from 0.09 to 0.37 ppm and zinc concentrations from 0.17 to 0.66 ppm in the pallial cavity fluid. These values were only slightly higher than the concentrations of these metals found in seawater samples taken at the site, indicating only very low levels of sequestration of heavy metals by G. demissa in the pallial fluid cavity. A comparable study of oysters (Crassostrea virginica) from the same site found lysozyme levels 10 times higher and zinc concentrations two orders of magnitude greater than in that in mussels reported here (Brousseau et al. 2014). These results suggest substantial interspecies variation in profiles of defensive agents involved in antimicrobial activities of marine bivalves and highlight the need for additional studies to characterize these differences.

The identification of the sex and sexual maturity of geoducks (Panopea japonica) is difficult because the outer shape of the males and females is indistinguishable. Moreover, depending on their size or age, the annual maturation cycle can vary. Vitellogenin (VTG) is a precursor protein of egg yolk. It has been studied as a biomarker for sex identification in geoducks. This article reports on the cDNA cloning of the P. japonica VTG gene for the VTG fragment. It was found to exhibit homology to known VTGs isolated from other marine molluscs, with more than 50% homology with oyster VTG. An enzyme-linked immunosorbent assay was developed to quantitatively detect the VTG level in geoducks. The VTG polyclonal antibody could recognize the extracted VTG in females, but the level of VTG in males was undetectable, providing a basis for an immunological assay for the identification of the sex and female maturational status of geoducks. Thus, this study established a simple and quantitative technique for the rapid identification of sex and/or maturation of females by using VTG in the hemolymph as a biomarker for the sampled geoducks without dissection or seriously injuring them.

Bivalve molluscs provide water quality benefits throughout mid-Atlantic watersheds, such as Chesapeake Bay and the Delaware River basins. Whereas most of the attention has focused on the role of the eastern oyster Crassostrea virginica, there are many other bivalve species, in both salt and fresh waters, that provide similar benefits. This review summarizes current knowledge regarding the capacity of diverse mid-Atlantic bivalves to filter particles and potentially enhance water clarity and quality. Species with the greatest clearance rates and population carrying capacity were also considered for their restoration and enhancement potential. Compared with eastern oysters, several additional species of saltwater bivalves and freshwater mussels are reported to filter water at rates that merit restoration attention and have been shown to attain significant population sizes. More work is needed to estimate system-carrying capacity and to eliminate restoration bottlenecks for some species—all bivalve species have constraints on their distribution and abundance. Nevertheless, a diversified, watershed-wide bivalve restoration strategy is likely to be more successful than a monospecific focus because it would address pollutant issues in more diverse places and multiple habitats along the river to estuary continuum.

Evaluating the spatial scale of biological variation in marine species aids understanding of the ways in which environmental selection pressures can shape life histories, population demography, and morphological traits. The Pacific geoduck Panopea generosa is an ideal candidate to investigate patterns of life history variation and morphological plasticity, as the species occurs over a large geographic range, inhabits different marine environments, and experiences intense fishing pressure in some locations. Six populations were sampled from Washington to Baja California (Mexico), from a mix of subtidal and intertidal habitats, to evaluate evidence for geographic variation in demography, life history, and shell morphology. Results provided evidence for a latitudinal cline with larger clams occurring in locations characterized by colder water temperature. Von Bertalanffy growth model analyses revealed significant spatial variation in asymptotic lengths across sampling locations. Correlations between environmental variables (sea surface temperatures and chlorophyll a) and growth parameters indicated that clams reached larger sizes at locations that were cooler and had higher primary productivity. Age structure and longevity analyses demonstrated that life expectancy was significantly lower at intertidal sites than at subtidal sites, potentially in response to increased fishing pressure at sites more easily accessed by humans at low tide. Morphological analyses (i.e., geometric morphometrics) revealed significant spatial differences in shell shape that did not follow a latitudinal pattern, but may be better explained by site-specific differences in sediment characteristics or other selective pressures in the environment. In a management context, these results may inform efforts to develop spatially explicit regulations for the Pacific geoduck fishery. Finally, this study provides a general framework for evaluating demographic variability in shellfish populations across large spatial scales.