Rearing Norway lobsters for restocking is a management option to compensate fishing overexploitation, but this requires, among other topics, developing specific pellet diets. The activity of digestive enzymes and the histological organization of the hepatopancreas were analyzed to assess the effectiveness of a pellet diet on digestive performance. Thirty animals were reared individually for 6 mo, fed with mussels and pellets or starved. Comparisons with wild lobsters were also conducted. Survival rate of lobsters fed with frozen mussels was the greatest. Trypsin and amylase activity in the hepatopancreas of the lobsters fed pellets was greater than that of other treatments. In contrast, pepsin activity in the gastric juice of starved animals was the greatest. Levels of alkaline proteases in the gastric fluid were greater in lobsters fed with mussels and the pellet diet in contrast to fasted animals. Amylase was greater in specimens fed frozen mussels. The greatest level of lipid accumulation observed in lobsters fed with the pellet diet indicated a physiological imbalance between the absorptive and transport capacity of the hepatopancreatic cells resulting from an excess of dietary lipids. These results might serve as a reference for future studies for formulating feeds specifically designed for Nephrops norvegicus.

Hemocyanin, which has numerous research and commercial biotechnology applications, is currently available from just two sources: the keyhole limpet and the horseshoe crab. Obtaining and purifying hemocyanin from these sources is a complex but necessary process because this compound cannot be synthesized in the laboratory. Lobster hemolymph, an abundant by-product of the lobster meat processing industry, could be developed as a new source of hemocyanin. A reliable and inexpensive method of extracting hemocyanin from lobster hemolymph would increase hemocyanin supplies through development of a value-added product from processing waste. Currently, ultracentrifugation is the most common commercial method of purifying hemocyanin. This technique, which requires several days of processing time, is not a reliable method of separating hemocyanin oligomers. We report new separation and purification techniques based on size-exclusion high-performance liquid chromatography, and methods of determining the quantitative and qualitative properties of hemocyanin derived from lobster hemolymph. In addition, an analytical and semipreparative method was developed to separate and purify hexamers and dodecamers from American lobster hemolymph. The shelf-life of hemocyanin hexamers and dodecamers extracted using the newly developed methods was determined to be more than 30 days with no observed degradation of the hemocyanin oligomers.

To understand more fully the larval dispersal and settlement of the snow crab Chionoecetes opilio in natural habitats, we tested the effects of temperatures ranging from ∼1–20°C and ∼1–18°C on the survival and developmental period of snow crab larvae in the zoeal and megalopal stages, respectively, through laboratory experiments. The survival rates of second zoeae and megalopae were significantly greater at 5–16°C and 5–14°C, respectively. There were no statistically significant differences among the survival rates of megalopae reared at 3–16°C, although greater survival rates were observed at 5–14°C. The mean numbers of days from hatching to second zoeae and megalopae and from megalopae to reach first crab instar were significantly shorter at warmer temperatures. Moreover, the relationships between mean temperatures and larval periods were well described by the heat summation theory equations. The threshold temperatures for larval development were estimated to be -2.24–0.63°C; they decreased with larval development as an adaptation for deeper vertical distributions in later larval stages. On the basis of larval distribution with respect to water temperature in natural habitats as well as the heat summation theory equations, the entire larval duration from hatching to first crab instar was estimated to be 74.4–123.4 days, which is similar to that in natural habitats inferred on the basis of the time lags in the occurrence of peak abundance between each larval stage.

Many crabs preferentially consume prey items that are relatively small to optimize energy gain and to minimize the risk of claw damage. The Atlantic mud crab Panopeus herbstii is an abundant predator on benthic epifauna, including oysters (Crassostrea virginica) and barnacles (e.g., Balanus eburneus) in southeastern U.S. saltmarsh ecosystems. Size selectivity by mud crab predators feeding on barnacle prey was examined using laboratory experiments in which individual mud crabs were offered a size range of ivory barnacles. Small (carapace width, <30 mm) and large (carapace width, >30 mm) crabs were offered small (test width, <7 mm), medium (test width, 7–8.9 mm), large (test width, 9–10.9 mm), and extra large (test width, >11 mm) ivory barnacles. Small crabs selectively consumed small barnacles at greater frequencies than other barnacles. Large crabs consumed proportionately smaller barnacles, relative to their carapace width, than small crabs. The relationship between predator crusher height and prey test width indicates that larger mud crabs reduce their risk of claw damage when attacking barnacles relative to smaller conspecifics. The observed barnacle critical size varied across predator size classes and was not strongly related to crab carapace width or crusher morphology. The median barnacle size of vulnerability increased with increasing predator carapace width. The observed ontogenetic size selectivity by mud crabs feeding on barnacles may be a more relevant predictor of prey vulnerability than barnacle critical size.

Progesterone is an important sex steroid that plays a vital role during ovarian development in crustaceans. In vertebrates, progesterone mediates reproduction via the progesterone receptor (PR). Previous studies have shown that PR is present in the ovary, hepatopancreas, and nerve tissues of some crustacean species. The Chinese mitten crab, Eriocheir sinensis, is an important aquaculture species in China and has become an invasive species in Europe and North America. A better understanding of the relevant reproductive mechanisms could potentially benefit artificial propagation and production of E. sinensis. Our intention was to immunorecognize and immunolocalize PR in the ovary, hepatopancreas, optic ganglion, brain ganglion, and thoracic ganglion of female E. sinensis using Western blot and immunohistochemistry. Changes in the distribution of PR were also investigated in these tissues during ovarian development. With an apparent molecular weight of 70 kDa, PR was identified in the optic, brain, and thoracic ganglion of female E. sinensis. During ovarian development, follicle cells were stained with positive PR at each ovarian stage. In germinal cells, positive PR was found in the cytoplasm only during the early ovarian development stages (I–III), whereas positive PR stained in the nucleus of germinal cells from stage III—stage V. In the hepatopancreas, PR was localized in the nucleus of resorptive cells as well as in the cytoplasm and nucleus of fibrillar cells for all stages of ovarian development. On the contrary, no PR-like substance was found in the other types of hepatopancreatic cells, such as blisterlike cells and embryonic cells, during ovarian development. However, a PR-like substance was detected in the nerve tissues of female E. sinensis. In the optic ganglion, PR was localized in the nucleus only of nerve cells. In the thoracic ganglion, PR was detected in the cytoplasm and nuclei of nerve cells during all ovarian development stages, with stronger detection during late ovarian development (stages III–V) rather than early (stages I and II). In addition, PR was localized in the brain ganglion, which is supported by evidence that the nuclei of nerve cells stained positively for PR antibody during all ovarian development stages. We suggest that progesterone not only regulates vitellogenesis and ovarian development directly by binding PR in the ovary and hepatopancreas, but also modulates indirectly ovarian development through nerve tissue.

The objective of this study was to determine the maximum sustainable yield (MSY) of the crab fishery in the Gulf of California by applying the catch-MSY method. This fishery occurs in two states—Sonora and Sinaloa, along the mainland coast of the Gulf of California—and involves two species: Callinectes hellicosus and Callinectes arcuatus. The main species supporting the fishery in both states is C. bellicosus, whereas C. arcuatus accounts for 5% of crab catches in Sonora and 20%–30% in Sinaloa. The catch-MSY method uses a set of viable r–k combinations to approximate MSY. The r–k combinations are the carrying capacity k and the maximum rate of population increase r for a given stock in a given ecosystem, which are required in most production models, such as the Schaefer model, to estimate MSY. Prior carrying capacity in this study was set arbitrarily from the maximum catches in a series evaluated to 100 times the maximum catch. This range ensures the real carrying capacity could be determined if catches were at MSY sometime during the period evaluated. Maximum potential could have been realized since 2006 for the Sinaloa stock and since 1996 for the Sonora stock. The evidence for these facts is that the catch per unit of effort decreased, and reductions were observed in the mean size of individuals; these changes occurred in the Sinaloa crab fishery. All methods devoted to management procedures of fisheries stocks entail a number of criticisms, and estimations of carrying capacity and stock biomass are costly; however, because sustainable fisheries are desired and data-poor stocks are common, a simple method like catch-MSY has proved be useful in the management of the crab fishery in the Gulf of California.

We investigated osmoregulatory ability of Pagurus minutus from three sites on the Waka River estuary (upper reach, river mouth, and middle). The sites have different salinity regimes and we tested whether crabs were adapted to their site locally or whether they showed phenotypic plasticity. The upper reach had a low salinity (∼16) during low tide, unlike the other two sites (∼28–31). The exposure of crabs from each site to seven different salinity levels (0–52.5) showed that P. minutus is a hyper-hypo-osmoregulator at all sites and is able to survive in 8.75–52.5 salinity levels for 24 h. Crabs from the upper reach, however, maintained greater hemolymph osmolarity in diluted media, and most of them were able to survive in even 0 salinity medium for 24 h. Crabs from the other two sites were not able to tolerate this condition and all died. Another experiment, involving a 1-wk acclimation to 5 decreasing salinity media (35 to 0), showed that the survival was about 1.3 times greater for crabs from the upper reach than from the other two sites. Because the crab density of the upper reach was significantly less than that of the other two sites, the upper reach is a marginal habitat established by asymmetrical larval dispersal from central saline habitats. Nevertheless, no crab from the saline sites survived exposure to the salinity of zero medium. These results suggest that the high osmoregulatory ability of crabs from the upper reach of the estuary does not represent a local adaptation; crabs acquire it after dispersal through developmental plasticity.

Outbreaks of mass mortality among cultured juvenile Chinese shrimp Fenneropenaeus chinensis occurred during summer 2010 in Jiangsu Province, PR China. Gross signs of disease included lethargy, swimming near the water surface and close to pond edges, pale red shell and appendages, breaking of antenna, and reduction in food consumption. Green and yellow bacterial colonies were recovered on thiosulfate citrate bile salt sucrose agar plates from the diseased shrimp. The predominant observed colonies were purified (VP1 and VR1) and their virulence toward postlarvae of Fenneropenaeus chinensis confirmed by bath experimental challenges. The phenotypic characteristics of the isolates, including morphological, physiological, and biochemical traits, were determined. Three housekeeping genes (16S rRNA, RNA polymerase a-chain (rpoA), and DNA gyrase B subunit (gyrB)) were sequenced, and phylogenetic trees based on rpoA and gyrB sequences were constructed. Phenotypic and genetic results confirmed the diseased shrimp were infected with both Vibrio parahaemolyticus and Vibrio rotiferianus. To our knowledge, this is the first report of V. rotiferianus as a pathogenic bacteria in shrimp. In addition, the activities of extracellular enzymes and hemolysin were also studied. Results showed that all the isolates (VP1–VP3 and VR1–VR3) produced β-hemolysis on rabbit blood agar, lecithinase, proteinase, and gelatinase, but DNase and lipase were not produced.

The aim of this study was to determine the reliability and accuracy of 3 commercially available handheld lactate meters when measuring hemolymph L-lactate in decapod crustaceans. The instruments tested were Accutrend Plus (AP), Lactate Scout (LS), and Lactate Plus (LP), and all models were tested in triplicate and compared with a commonly used enzymatic kit for L-lactate quantification (TB-kit). The Norway lobster Nephrops norwegicus and the European lobster Hommarus gammarus were used as model organisms, with emersion as an invoker of hemolymph L-lactate. Between-method comparisons were investigated by determining correlations (Pearson's r) and concordance (concordance correlation coefficient (CCC) and Bland-Altmand's 95% limit of agreement (95% LOA)) between handheld instruments and TB-kit. Within-instrument variation was tested by calculating the coefficient of variation (CV), and the average absolute deviation from the mean (AD). The within-instrument variation was low for all models (CV, 3.8–6.1%; AD, <0.3 mM), showing high reproducibility of technical replicates. A significant correlation with TB-kit was found for all handheld instruments (AP, r = 0.970; LS, r =; 0.956; LP, r = 0.950). For both AP and LS, there was a moderate and significant concordance with TB-kit (AP, CCC = 0.945; LS, CCC = 0.940). The mean difference from TB-kit was -1.42 mM (95% LOA,-4.50–1.66 mM) for AP and 1.19 mM (95% LOA,-3.13–5.51 mM) for LP. Emersion experiments with the European lobster showed that AP and LS were in line with TB-kit in terms of detecting differences in L-lactate levels between groups of animals. As a result of the high frequency of error readings from LP, this instrument was not considered reliable when measuring L-lactate in decapod crustaceans. In conclusion the handheld instruments AP and LS are found to be reliable instruments when measuring hemolymph L-lactate in decapod crustaceans. Comparison of results from different methods should be avoided, and in cases when accurate absolute measurement of L-lactate is needed, methods allowing for greater accuracy and resolution should be used.

Georges Bank is the most productive sea scallop fishing ground in the world, but little is known about the regional spawning patterns. The sea scallop rotational management plan is based on yield projections estimated from shell height/meat weight relationships. Semiannual spawning may influence yield projections, impacting fishery allocations. This study identifies spawning events at two locations on Georges Bank: one in Closed Area I (CAI) and the other in Closed Area II (CAII). We hypothesize that spawning is semiannual, spring spawning is incomplete compared with autumn spawning, and reproductive stage differs temporally between areas. Scallops (n = 1,871) were collected during a monthly dredge survey in these two areas from two sites from March 2011 through June 2013. Tissues from scallops (shell height ∼130 mm) frozen at sea, were oven-dried and the gonosomatic indices (GSIs) were analyzed to identify spawning events. Oocyte diameter was measured to determine maturity. Bottom temperature was recorded. Semiannual spawning occurred in both closed areas. Spawning rates were similar, but autumn spawning was greater in magnitude than spring spawning. The timing of gametogenesis was similar between sites. Bottom temperature patterns suggest different oceanographic conditions between areas. A semiannual sea scallop reproductive cycle on Georges Bank could influence recruitment and growth assumptions affecting future management decisions.

In this study, broodstock animals of the tropical scallop Nodipecten nodosus were submitted to maturation trials using two dietary sources of astaxanthin: dried microalgae Haematococcus pluvialis (Algamac AST) and live microalgae obtained from in vitro cultures. The influence of astaxanthin on broodstock maturation was assessed by analyzing stages of gonadal development, accumulation of astaxanthin in sexual organs, animal fecundity, and recovery success rates of larvae and spat. Two experiments (1 and 2) were performed to test dietary concentrations of dried H. pluvialis mixed with live microalgae (Isochrysis sp., Chaetoceros muelleri, and Skeletonema sp.). A third experiment tested 50% dried H. pluvialis with live H. pluvialis versus a diet composed of live C. muelleri. All diets were calculated to a final concentration of 7.5 × 10⁴ algal cells/mL¹. In experiments 1 and 2, the 50% Algamac AST diet resulted in a greater (P < 0.05) accumulation of astaxanthin in the female portion of the gonad, and all diets were found to improve gonad maturation. In addition, the presence of dried microalgae in the diet enhanced D-larvae and pediveliger survival. In experiment 3, live H. pluvialis in the diet resulted in a greater accumulation of astaxanthin in the female portion of the gonad and a greater percentage of recovery of D-larvae and pediveligers. The results demonstrate that dietary carotenoids affect N. nodosus larval viability positively.

Knowledge of changes in the interdependence of a species' populations for continued existence (connectivity) and of the forces driving connectivity patterns is critical for management and conservation of the species. Population genetics can be used to investigate population connectivity. Combining population genetics with climatic, environmental, and biological (external) factors that can influence population structure and connectivity can lead to a greater understanding of the forces influencing population dynamics. We deciphered the population genetic structure and connectivity patterns of bay scallops (Argopecten irradians concentricus Lamarck) from Florida Gulf of Mexico waters using allozyme-locus and mitochondrial DNA population genetics data from samples representing four consecutive generations. We evaluated bay scallop population genetic relationships within the context of habitat, hydrodynamic, and environmental variation, and concomitant spatial patterns in the abundance of adult and recently recruited scallops to infer the influence of these factors on bay scallop population structure. Florida Gulf bay scallops form a hierarchical, mixed-model, source-sink metapopulation with intergenerational variation in connectivity that seems to be influenced by the factors we considered. An El Niño event that occurred during 1 y caused climatic and environmental change that greatly reduced subpopulation connectivity, allowing us to understand more completely the potential relative importance of the other external factors on change in metapopulation connectivity over time. Our study illustrates the value of using multiple genetic markers, sampling for multiple years, and integrating data from multiple external factors for understanding the population genetic structure of species for adaptive management.

Although the Japanese scallop Mizuhopecten yessoensis is the variety used in the largest production of scallops in the world, knowledge about its predators is very limited, and gastropods have not generally been recognized as a predator. This study demonstrates the impact of predatory gastropods on the Japanese scallop through a field survey and laboratory experiments. The 4-y field survey at a lagoon in northern Japan demonstrated that the frequency of scallops that have boreholes on their shells represented 11.3%–73.8% of dead individuals at 3 y old (shell height, >90 mm) that would have been harvested 7 mo later. By calculating the natural mortality of scallops after their release on the sowing—culture grounds in the lagoon, we estimated that 17.8% of the released scallops were attacked by drilling animals. This estimation, however, probably underestimates the impact of drilling predators, because the drilling frequency on small (young) individuals (shell height, <55 mm) was 10 times greater than on large (old) individuals (shell height, >99 mm) in the laboratory. Observations of the position of boreholes on the shells suggest that drilling animals accessed the left (upper) valve of the shell and drilled it randomly. By conducting another laboratory experiment on all potential drilling gastropods in the lagoon, 2 gastropod species—Pteropurpura (Ocinebrellus) inornatus (Récluz, 1851) and Boreotrophon candelabrum (Reeve, 1848) of the family Muricidae—were identified as the drilling animals. Because we also observed their behavior experimentally and there was no difference in the shapes of boreholes drilled by P. (O.) inornatus, B. candelabrum, and unidentified animals in the field, we conclude that these 2 muricid gastropods are the predators of the Japanese scallop and that the drilling frequency observed in the field reflects the predation frequency of those gastropods. The current study suggests that predation by the muricid gastropods has been overlooked in the management of Japanese scallop fisheries, even though it is highly probable that the distribution areas of predatory gastropods overlap many harvest areas of the Japanese scallop.

The oyster fishery is 1 of the most important coastal fisheries in Mexico. Management is based on a minimum legal size of 80 mm and several seasonal bans that vary along the coast of the Gulf of Mexico. We describe the gonad development cycle of Crassostrea virginica (Gmelin 1791) along the Mexican coast of the Gulf of Mexico for 5 lagoons for the years 2000 and 2004, between latitudes 21°41′16.75″ N and 18°23′51.08″ N. Significant differences in duration and intensity were observed among reproductive stages associated with different environmental conditions. Gametogenesis and mature stages correlated positively with temperature and total chlorophyll, respectively. Spawning correlated negatively with salinity in both years. Maturity correlated positively with total chlorophyll levels. The reproductive stages varied from seasonal, a few months, to continuous throughout the year. Recovery, expressed as the number of organisms in postspawning and resting stages, was fast for populations that presented constant gametogenesis and spawning, with less than 50% of the population in postspawning and resting stages. Environmental fluctuations in total chlorophyll are the regulating factors for gametogenic activity, rather than latitudinal temperature variations. This makes monitoring environmental conditions in the lagoons or gonad development a necessity to predict reproduction and recruitment for proper management of the oyster resource.

A selective breeding program for Crassostrea virginica was established in 1997 as part of an initiative in Virginia to address declining oyster harvests caused by the two oyster pathogens Haplosporidium nelsoni (MSX) and Perkinsus marinus (Dermo). Housed in the Aquaculture Genetics and Breeding Technology Center (ABC), the objective of the program was to develop and disseminate disease-resistant lines that would enable an oyster culture industry. Today, culture of disease-resistant cultivars accounts for more than 90% of oyster production in the state, where 28.1 million half-shell oysters and 2 billion eyed larvae were sold in 2012. Results of our line development program as of 2006 are reported. Eight ABC lines from 3 genetic groups—East Coast (EC), Louisiana (LA), and hybrids between the 2 (HY)—and 1 wild control line, were produced and tested. These 9 groups were deployed in 4 replicates across 4 Virginia sites characterized by low (Kinsale (KIN)), medium (York River (YRK) and Lynnhaven (LYN)), and high (Wachapreague (WAC)) salinity regimes. Groups were sampled routinely for survival, growth, and disease diagnosis between November 2004 and December 2006. At KIN, where salinity was low and below the threshold for MSX and Dermo, survival was 41%–46% greater than survival at the other 3 sites by the end of the trial. Where the diseases were present (LYN, YRK, and WAC), ABC lines in general had greater survival than the control, but this varied by genetic group. The EC groups had 52%–82% greater survival, the HY groups had as much as 40% greater survival, and the LA groups performed worse than the control. Poor performance of the LA groups was a result of their susceptibility to MSX, and the majority of them died before the end of the study. The genetic effects varied with site, and the rank of the lines was inconsistent, such that the best line in one site was, in some cases, one of the worst in another. Genotype-by-environment interaction is clearly driven by disease and salinity. Growth was also influenced by site, genetic group, and an interaction between them. Compared with the wild control, ABC lines were 31%, 20%, 42%, and 24% heavier at the end of the trial in the KIN, YRK, LYN, and WAC sites, respectively. However, unlike survival, the best performers were those from the LA and HY groups. Again, line rankings changed across sites. For this reason, a salinity-specific breeding strategy to develop lines that perform optimally within a salinity range has been adopted.

Oysters of the genus Crassostrea are considered good examples of an r-selected marine invertebrate with small egg size, high fecundity, and multiple spawning events per year, each characterized by significant individual weight loss. Historical (decadal) data for the Virginia portion of the Chesapeake Bay support these generalities. We present recent (subdecadal) data, collected for natural Crassostrea virginica broodstock of populations in the Piankatank River, Virginia. The relationship is described between oyster size, fecundity, spawning periodicity, and egg viability for natural broodstock. Oysters collected throughout the summers of 2010 through 2012 and induced to spawn by thermal cycling released viable eggs on 7 dates (n = 119 oysters, 35 male, 84 female; shell length (SL) range, 58–113 mm). Oysters were opened to examine sex ratio on four additional dates (total n — 242 oysters, 82 male, 160 female). Fecundity varied in the range 10⁵-1.2 × 10⁸ eggs. When all data are considered in unison, no strong relationship with SL is evident; however, when eliminating the artifact of data corresponding to minimal egg release, a much stronger relationship, comparable with that reported in older literature, emerges. Female fraction (Female/(Female Male)) was consistently more than 1 in oysters larger than 60 mm in SL (estimated age, ≥2 y), generally in accordance with recently published literature on the species in the mid-Atlantic. The size-versus-fecundity relationship does not appear to be greatly influenced by disease prevalence/ intensity. The temporal sequence of spawning activity was not observed to continue after midsummer and is not commensurate with a cumulative degree-day estimator during the latter half of the well-documented historical spawning season. A size-fecundity estimator for the Piankatank River oysters provides a basis to estimate the disproportionate value of larger/older (≥3 y) oysters in the system, and provides additional input to the fine-tuning of a previously developed rotational harvest schedule for the river stock. The possible impact of recent changes in water quality, seasonal occurrence of dinoflagellate blooms, and/or long-term impacts of changing regimes were not examined in detail in this study but are suggested as worthy lines of future investigation.

Several restored oyster (Crassostrea virginica Gmelin) reefs in Pamlico Sound, North Carolina, have experienced recent population crashes, potentially caused in part by clionid boring sponge infestation of the marl rock (a calcium carbonatemud composite material) commonly used as a reef substrate and of the shells of oysters that colonize the marl reef foundation. The composition and porosity of marl may make it vulnerable to infestation by carbonate bioeroders, particularly clionid sponges. The objective of this study was to quantify the effects of carbonate (CaCO₃; oyster shell, marl) versus noncarbonate (non-CaCO₃; granite, concrete) reef-building substrates on C. virginica demographic rates, including oyster density and oyster growth, on experimental reefs constructed along the salinity gradients of two estuaries in coastal North Carolina. There were no differences in oyster density among substrate types through the first 6 mo of reef sampling, although at 12 mo after reef construction, differences in density among substrates had emerged. Sites in high-salinity areas had much greater oyster recruitment than up-estuary, lower salinity locations. Early-life growth (<6 mo) of oysters was assessed for recruits to experimental reefs, with few differences seen in oyster mean valve length or growth rate on different substrate types. These results support consideration of non-CaCO₃ materials, particularly concrete, for future oyster reef restoration, especially in high-salinity areas where the boring sponge Cliona is abundant, because both oyster density and growth were similar on oyster shell and concrete substrates as long as 1 y after reef construction.

This study assessed the influence of temperature on gonadal tissue maturation in the mangrove oyster Crassostrea gasar in the laboratory. The oysters were held at three water temperatures (18°C, 22°C, and 26°C), and the control oysters were maintained under cultivation in the environment. Every 10 days, 10 oysters from each treatment were examined for condition index and 10 for histological analysis. In the 22°C, 26°C, and field treatments, gonadal tissue maturation was observed, with no significant difference among treatments. The 18°C treatment was significantly different compared with the groups maintained at other temperatures, but did not demonstrate an improvement in gonadal tissue maturation. The results suggest that at 18°C, an accumulation of energy reserves occurs, and at temperatures greater than 22°C, gamete maturation occurs. In this study, the animals maintained in the field environment exhibited the same maturation conditions as those maintained in the laboratory, suggesting that this species can be stimulated in the laboratory, apart from the period of natural maturation.

As the agent of Dermo disease, Perkinsus marinus causes significant mortality and reduced fecundity its eastern oyster host, Crassostrea virginica. Passive dispersal of P. marinus between hosts subjects parasite movements to control by water currents in estuarine systems, potentially limiting connectivity among parasite populations in different estuaries. Given recent evidence for sexual reproduction in P. marinus, estimates of gene flow among locations may provide insights into this parasite's epidemiology. In this study, 1,082 wild oysters were collected from 2002 to 2008 at 15 geographical locations encompassing 4,800 km of the Gulf of Mexico and Atlantic coasts of the United States. Of these, 742 oysters (68.9% prevalence) were determined to be infected by P. marinus. Among infected oysters, 374 were determined to be infected by a single parasite genotype based on amplification of seven microsatellite loci, and therefore were amenable to analysis. Allele frequencies differed significantly among most locales, but there was no indication of isolation by distance. Four distinct clusters of multilocus genotypes were identified by analyzing genetic distances among individuals and by using Bayesian assignment tests. One lineage occurred in many locations, whereas the others were limited to a particular region or disjunct locations. Two lineages were associated with recent range expansion. Altogether, local assemblages of P. marinus are characterized by mixtures of distinct sympatric populations that undergo only infrequent recombination. By mixing divergent strains, long-distance dispersal and/or anthropogenic introduction may play an important role in the evolution of P. marinus and spread of Dermo disease, whereas locally, high-frequency strains may represent focal epizootics.

Sources of fecal contamination in two shellfish-bearing tidal rivers (Coan and Little Wicomico) adjacent to the lower Chesapeake Bay in Virginia were identified using antibiotic resistance analysis (ARA) and pulsed-field gel electrophoresis (PFGE) on Escherichia coli. Both rivers contained numerous shellfish beds that were closed to harvest as a result of fecal contamination. Host-origin fecal samples (n = 519) were collected and used to build a regional library for each method (8 E. coli isolates per sample for ARA, 4,152 total; 4 isolates per sample for PFGE, 2,076 total). The best classification rule for the host-origin data set was generated by discriminate analysis (nonpooled covariance, jackknife estimates, 80% threshold), and the average rate of correct classification (ARCC) for the libraries was 70.4% for ARA and 83.3% for PFGE. The libraries were challenged for predictive ability with sets of isolates that represented reproducibility, accuracy, and robustness. The libraries were used to classify sources of E. coli isolated monthly for 12 mo (September 2001 to August 2002) from 15 sampling stations in the two rivers (180 total samples), and ARA was performed on 24 E. coli isolates/sample, or 4,320 total isolates (6 isolates per sample for PFGE, or 1,080 total isolates). Humans and birds were identified by both methods as the dominant sources of fecal bacteria in both rivers over all stations and months combined. Although many stations exceeded fecal count standards, rainfall was a factor at only a few stations, and season had little effect. There was a 73.4% and an 80.7% average agreement over sources for the host-origin isolates and water sample isolates, respectively, that were classified by both ARA and PFGE. Disagreement between the two methods was a result of isolates that PFGE, the more sensitive and accurate method, could not identify, whereas ARA placed the same isolates in one of the source categories. Inclusion of the newer DNA-based source tracking methods that do not require cultivation or libraries is described, along with how these methods can provide guidance to confirm the human-origin pollution that was found in the condemned shellfish waters when the study was done. These same waters were still condemned in 2013, and the newer DNA-based methods plus better sampling designs are more likely to help identify the exact locations where such human pollution originates.

This study compared the carbon isotopic composition of individual amino acids from muscle tissue and shell organic matter inclusions in Crassostrea virginica collected along a salinity gradient in the Rookery Bay estuary, Florida. Theintent was to assess the extent to which environmental signals relating to spatial and temporal variation in carbon sources were recorded in the amino acids of these materials. There was a trend toward enrichment in δ¹³C in all amino acids moving seaward along the transect in both organic matter pools, consistent with diminishing influence of terrestrial (C₃) production and increased contributions of marine production. The magnitude of this trend was identical for both tissue and shell organic matter, although the values for several constituents of the shell organic matter (aspartic and glutamic acids and glycine) were consistently depleted by approximately 3‰ relative to their equivalents in tissue samples. Other amino acids were directly comparable despite a 2‰ offset in bulk isotopic compositions. Sites were distinguishable from one another in both the tissue and shell organic matter data sets. Although samples were collected across an annual cycle to examine seasonal change, no seasonality was found. The results presented here demonstrate that compound-specific amino acid analysis of carbon isotopes is a useful tool in the analysis and interpretation of biomineral organic materials.

Characterizing density patterns of fish and crustaceans across estuarine habitat types can provide useful information regarding their relative value. The oyster reef complex within Sabine Lake Estuary is the largest known in the United States with no record of commercial harvest, and it presents a unique opportunity to understand the habitat value of an unfished reef system in comparison with adjacent estuarine habitats. High abundances of relatively large oysters with complex formations were observed throughout the 2-y study period. Average densities of fish and crustaceans were 6 times greater at the marsh edge than the nonvegetated shallow habitats, and 40 times greater than both the oyster reef and nonvegetated deep habitats. Low faunal densities observed in the oyster reef habitat may be the result of spatial configuration and connectivity to surrounding habitats, collection limitation resulting from its large vertical relief (>1 m) and complex 3-dimensional structure, or habitat selection resulting from water depth. Because the majority of crustaceans and resident and transient fish were observed within the marsh edge and nonvegetated shallow habitats, it is difficult to determine whether oyster reefs within Sabine Lake Estuary provide essential habitats for these species. Although low densities of organisms were observed in the oyster reef habitat, multivariate analysis indicates that the unfished reef supports a unique community of fish and crustaceans. Results provide a valuable baseline for future conservation, restoration, and management actions as we seek to understand more completely and to protect important estuarine habitat types.

The preferred temperature of Tegula regina was determined in a horizontal thermal gradient with organisms acclimated to 16°C, 19°C, and 22°C using to acute method, with a preferred temperature of 19.7 ± 1.8°C for the day cycle and 18.8 ± 1.2°C for the night cycle. The final preferred temperature determined for marine snails was 19.2 ± 1.5°C. The displacement velocity decreased to an interval from 99.1 cm/h to 62.5 cm/h. During the third hour, when organisms detected the preferred temperature, the velocity diminished gradually from 25.8 cm/h to 7.5 cm/h. Critical temperature maxima (CTMax), which refers to the temperature at which at least 50% of the experimental group displays a loss of attachment, was measured at three acclimation temperatures (16°C, 19°C, and 22°C). At the acclimation temperature (16°C), 50% of the experimental group had an attachment loss at a CTMax of 29.3°C. At a warmer acclimation temperature (22°C), the observed CTMax was 31.2°C. Marine snail oxygen consumption rate increased significantly (P < 0.05, 31%) from 16°C to22°C.

The potential of trace and minor elements within biominerals to track the larval dispersal of bivalves was investigated by examining elemental composition in early larval shell of the northern quahog (hard clam) Mercenaria mercenaria. Larvae were cultured in three shellfish hatcheries using the adjacent estuarine waters of the southern Delmarva Peninsula in Virginia. Spatial distinction (∼1–50 km) and temporal stability (triweekly) of elemental concentrations was assessed using inductively coupled plasma mass spectrometry. Seventeen minor and trace elements were present at detectable levels in all shell samples: Ca, Mg, Ti, Co, Ni, Zn, Se, Rb, Al, V, Cr, Mn, Cu, Sr, Ba, Pb, and U. Discriminant function analyses using metal-to-Ca ratios as independent variables assigned hard clams to their hatchery of origin correctly, with 100% success. The ratio Cr:Ca proved to be the most effective discriminator, explaining 78.1% of among-group variance. Elemental concentrations within early larval shell also differed temporally. Discriminant function analysis classified individual spawning events with 100% success, with Al:Ca explaining the bulk of among-group variance (81.4%). Despite temporal variability of elements within larval shell, it was possible to resolve elemental signals spatially among hatcheries regardless of spawning date. These results demonstrate for the first time that the chemical composition of hard clam larval shell records spatial elemental signatures with the potential to trace the environment of natal origin as well as subsequent dispersal trajectories of this economically important species.

A field and modeling study of the food supply and demand of mussel (Mytilus edulis) rafts in Maine established the hydrodynamic and particle consumption characteristics of shellfish aquaculture structures. Mussels on rafts filtered about 8 × 106 L/h and consumed about 40 g chlorophyll a (chl a)/h under favorable conditions. Because of the drag of the culture ropes and predator nets, velocity inside the rafts was reduced by 75%–80% in relation to ambient conditions. Chlorophyll consumption by mussels increased with increased food (chl a) concentration and also with increased water velocity inside the rafts. Clearance rates per raft also increased with food concentration. Model results allow for an estimation of water flux and seston depletion within the rafts through the use of point measurements and correction factors. Water velocity measurements taken mid depth in the middle of the rafts underestimated the mean flow through the raft by 10%. Measurements of current velocity and chl a concentration taken mid depth in the middle of the rafts underestimated the mean particle consumption rates by 13%. Model results and field data indicate that mussel raft hydrodynamics are a function of raft orientation to current direction, mussel raft size, raft aspect ratio, the presence of predator nets, the presence of multiple rafts, rope spacing, and rope diameter. Mussel raft design, placement, and biomass may be adjusted to optimize hydrodynamics and conditions favorable for improved mussel growth rates. Recommended flow speeds through experimental mussel rafts with a cross-sectional area of 121 m2 require a minimum outside flow speed of 14–23 cm/sec.

The green mussel Perna viridis (Linnaeus 1758), a native of the Indo-Pacific, has been introduced to the Atlantic basin and Caribbean Sea. It was reported first in Cienfuegos Bay, Cuba, in 2005. This species has proliferated quickly and now constitutes an economic as well as ecological problem, interfering with the operations of a local thermoelectric plant. The objectives of this study were to document the spatial and temporal variation in P. viridis density across Cienfuegos Bay and to examine the relationship between P. viridis density and water-quality patterns within the bay. The presence and relative abundance of P. viridis were surveyed qualitatively in Cienfuegos Bay in January 2011. Four sites were selected for additional investigation, and mussel density was estimated 6 times during 2011 and 2012. Temperature, salinity, and dissolved oxygen also were measured. We found that P. viridis density differed across Cienfuegos Bay both temporally and spatially, and that, although salinity may play a role in green mussel distribution and density, other factors were also important. The greatest densities of P. viridis were located near the city of Cienfuegos on the northeastern shore of the bay. The results of our systematic sampling also revealed dramatic temporal variation in the Cienfuegos Bay P. viridis population. During the 22-mo study, green mussel density at two of the sampling sites declined by an order of magnitude. There are several possible explanations for the dramatic decline in P. viridis density during the sampling period. Among them are mortality resulting from stressful environmental conditions and removal through harvest, both coupled with low recruitment rates. The decline of the population in the bay suggests that this species is not a candidate for a commercial fishery and that manual harvest may be an efficient means of eradication, if desired.

Observations are presented to elucidate the complex and highly efficient feeding mechanisms and habits in the common Atlantic slippersnail, Crepidula fornicata. Using a newly designed video system coupled with video endoscopy and microscopic observations, collection of food particles throughout the feeding cycle was documented. The process is described from postcapture particle transport on the gill, to production and consumption of the food cord, and the results were compared with controversial historical records and descriptions of feeding, especially with regard to the roles of the radula, food pouch, and a purported mucus net or filter. The food cord is produced continuously and is the dominant mode of feeding. Capture of food cords is efficient, but often sloppy; more than 10% of food volume production is ultimately expelled to the exterior of shell, making these energy-rich cords available to other benthic feeders. Although it was observed that the ciliated food pouch produces balls of mucus-laden food, these balls account for ∼10% of feeding events, and less than 1% of food volume production and ingestion; in other words, the food pouch contributes little to the feeding process or the production of pseudofeces. Coprophagy was also noted fairly regularly, clearly a function of the position of the anus in relation to the gill and site of production of the food cord. Video endoscopy demonstrated that food particles are captured on the frontal surface of the filaments and moved distally by the frontal cilia of the gill. Immediately after capture, particles are incorporated into fine mucous strings on the frontal surface and carried both distally and obliquely across the filaments. At the distal edge of the gill, the mucous strings enter the neck canal, are incorporated into a food cord, and are pulled anteriorly, resulting in the oblique movement of material on the gill. The overlap of mucous strings (those moving distally and those moving obliquely) often gave the appearance of a "mucous net," as has been described in older studies with less sensitive means of visualization. The results presented clearly demonstrate there is no mucous net formed, and a model is proposed to describe the capture and movement of particles, providing clarification of the process and new interpretations of the suspension-feeding process.

The octopuses Octopus hubbsorum and Octopus mimus are two species of octopuses that inhabit shallow waters of the eastern Pacific Ocean. The former species is found in the north, from the Gulf of California to Oaxaca, Mexico, whereas O. mimus lives in the south, from Peru to Chile. To infer the phylogenetic relationships between these species we used the mitochondrial genes cytochrome oxidase subunits I and III, and r16S with the aim of comparing their genetic distances with those of other Octopus sp. The genetic distance values between both species estimated per gene or concatenated were low (0%–1.6%) in comparison with other interspecific distances values (4.6%–18.4%). Application of 10× rule showed there is no overlap between intra- and interspecific octopus distances, whereas the application of the 4× rule confirmed that both octopuses belong to the same lineage. The resolved topologies with maximum parsimony and Bayesian approaches clustered the specimens of O. hubbsorum and O. mimus in a single clade with high bootstrap and posterior probability values (100 and 1.0, respectively). These results allow us to suggest that O. hubbsorum and O. mimus could represent the same species.

Two hundred sixty-one octopuses were obtained from August 2006 to June 2007 in Bahía de Los Angeles, BC, Mexico. Sizes ranged from 58–190 mm in mantle length. Diet was determined from 3 sources: the digestive tract analysis (hard rests), accumulations of hard prey remaining in refuges, and live prey present during capture. Ripe females had the greatest fullness weight index (FWI) whereas spawning/spent females had the lowest. During the spring, female and male octopuses showed the greatest FWI, whereas in summer they showed the lowest, coinciding with the spawning/spent stage. A total of 76 prey items from 8 phyla were found, with Mollusca being the most important phylum and xanthid crabs the most important prey year-round. During autumn and winter, more bivalves were consumed, whereas more crabs were consumed in spring. Males fed mainly on crabs during all gonad development stages, but spent males fed mostly on molluscs. In contrast, females fed mostly on molluscs, except ripe females, which included more crabs in their diet. The octopus Octopus bimaculatus appears to be a specialist consumer, and this selectivity could be a consequence of different energetic demands of each sex during the gonad ripening process.

Age and growth of the ark shell Scapharca broughtonii in 3 bays in Japan (Mutsu, where ark shells are cultured, and Nanao and Sendai, where they occur naturally) were examined using a shell sectioning and staining method. When a water-based marking pen was used to stain the opaque zones only in shell cross-sections, unstained translucent zones (i.e., growth rings) were clearly observed. Based on seasonal changes in marginal structures of shell cross-sections and marginal growth indices (MGIs), growth rings were estimated to be formed annually in summer when shell growth ceased. The estimated maximum ages for ark shells from Nanao and Sendai bays were 6 y and 20 y, respectively, whereas for Mutsu Bay the maximum age was not calculated because we had only young, cultured specimens, von Bertalanffy growth models were estimated as L_t = 80.1(1 -e^{-0.365(t 0-160)} for Mutsu Bay, L_t = 115.3(1-e^{-0.478t-0162)} for Nanao Bay, and L_t = 84.8(1 -e^{-0.473(t 0.222)} for Sendai Bay. There was no significant difference between von Bertalanffy growth models fitted for the northern and southern areas of Sendai Bay. Comparing among the 3 bays, faster shell growth may occur in the locality where water temperature is warmer.

The paper “Broadening the Genetic Basis of the Atlantic Bay Scallop Argopecten Irradians after Interspecific Hybridization and Backcrossing” authored by Shoudu Zhang, Li Li, Fucun Wu and Guofan Zhang and published in JSR 32(3) is being officially retracted as a publication in the Journal of Shellfish Research. The paper was originally published in Marine Sciences, Volume 36 (8) in 2012 in Chinese with an English Abstract. This constitutes duplicate publication. The authors have agreed to this retraction. The paper is no longer citeable.