Members of the bivalve molluscan family Spondylidae were very important elements in the world view of pre-Hispanic cultures of America, and today remain as symbols of culture heritage in contemporary society. In recent decades, given the importance they have for crafts and jewelry, as well as for fisheries and gastronomy, their exploitation has caused a drastic decrease in natural populations leading to restrictions in fishing. In the present review, data about Spondylus species of eastern Pacific Ocean, describing the symbolism, taxonomy, distribution, biology, and ecology, their status as exploitable resources, the advances in aquaculture of these species, as well as management experiences and conservation efforts are presented.

The sea scallop Placopecten magellanicus (Gmelin, 1791) fishery is the most valuable wild scallop fishery in the world. Landings are primarily adductor muscles, which are ideally creamy white and firm. Recently, an increasing number of dark brown to gray, flaccid, and stringy meats have been caught in areas of Georges Bank and the mid-Atlantic, causing concern in industry and management. The mortality of gray-meat scallops was investigated, and an anesthetization procedure was developed allowing assessment of meat color in live scallops for laboratory experiments. The mortality rate of gray-meat scallops compared with white-meat scallops was tested. Gray-meat infection was swift and fatal; 26 of the original 28 gray-meat scallops died, whereas only 1 of 28 white-meat scallops died. The gray-meat condition was clearly associated with apicomplexan parasite infection intensity. Gray-meat scallops were identified visually, with image analysis computer software, and cell counts of apicomplexan nuclei. Secondary infections and stressors, including the effect of senescence, boring worm (Polydora sp.), and boring sponge (Cliona vastifica), were examined. Shells exhibiting high levels of boring sponge and worm damage had significantly higher incidence of gray-meat scallops. The prevalence of gray meats in a scallop population changes the shell height-meat weight relationship and the estimates of natural mortality and fishing effort used in stock assessments. Understanding the impacts of this disease and how to manage the fishery in its presence is important for the future of the fishery.

Bacterial pathogens are a major cause of mortality in bivalve hatcheries, and outbreaks can result in shortages of seed supply to the grow-out industry. The use of probiotic bacteria is a potential preventative measure to limit the impact of bacterial diseases. Previous research showed that the marine bacteria Phaeobacter inhibens S4 (S4) and Bacillus pumilus RI06—95 (RI) protect larval eastern oysters (Crassostrea virginica) when challenged with the pathogens Vibrio tubiashii RE22 (now Vibrio coralliilyticus RE22) and Roseovarius crassostreae CV919-312^T. In this study, these probiotic bacteria were tested under hatchery conditions. Daily addition of S4 and RI (10⁴ colony forming units (CFU)/ml) to 100-l culture tanks resulted in a significant decrease in the levels of total Vibrios in water and tank surfaces (P < 0.05), but not in oysters. Larval growth and survival was unaffected by the probiotic treatments. Larvae treated with probiotics in the hatchery showed significantly less mortality than larvae from control tanks when exposed to 10⁵ CFU/ml of V. coralliilyticus RE22 for 24 h in a laboratory challenge. These results suggest that S4 and RI are safe and potentially effective tools to limit disease outbreaks in oyster hatcheries.

Hatcheries providing seed for bivalve mollusc aquaculture can suffer from disease outbreaks resulting in high losses of larvae. Previous research demonstrated the effectiveness of candidate probiotics Phaeobacter inhibens S4 (S4) and Bacillus pumilus RI06-95 (RI) in protecting the larvae of eastern oysters Crassostrea virginica, against bacterial challenge. In this study, the ability of this probionts in protecting larvae of other bivalve species, including northern quahog Mercenaria mercenaria, bay scallops Argopecten irradians, blue mussels Mytilus edulis, and razor clams Ensis directus, was investigated. Pretreatment of larvae with 106 colony forming units /ml probiotic S4 and a mixture of S4 and RI protected bay scallop larvae [relative percent survival (RPS): 69% ± 4%]. In pilot-scale hatchery trials, daily additions of candidate probiotics to the water of static tanks containing northern quahog or bay scallop larvae had no significant impact on larval growth and survival. Daily treatment of tanks with the probiotic RI led to significantly lower levels of Vibrio spp. levels in water and larvae compared with control on day 8 of the northern quahog hatchery trial (P < 0.05), but not for the bay scallop trial. Exposure of bay scallop larvae to S4 and a mixture of S4 and RI in the hatchery provided partial protection to experimental challenge (RPS: 55% ± 14% and 54% ± 4%, respectively). Treatment of northern quahog larvae with probiotics in the hatchery did not lead to increased protection to bacterial challenge. These candidate probiotic strains appear to have species-specific protective effects for bivalve larvae.

Spatial and temporal genetic structure of the eastern oyster Crassostrea virginica was examined along the coast of North Carolina (NC); utilizing a fragment of the mitochondrial large (16S) ribosomal subunit gene sequence known to distinguish three regional haplotypes in C. virginica—North Atlantic, South Atlantic, and Gulf of Mexico. Significant geographic genetic structure was identified among all populations studied, with little temporal genetic variation observed over the 9-y sampling period. The results are consistent with those of previous studies analyzing geographic variation in mitochondrial DNA16S sequence data, which revealed a genetic discontinuity between North and South Atlantic oyster assemblages along the NC Coast. The increased geographic resolution and duration of sampling in this study revealed a sustained significant shift in genetic composition between Pamlico Sound populations and southern NC populations of C. virginica. These results suggest that a prolonged or persistent barrier impacting larval dispersal or post settlement survival exists between these regions limiting gene flow between North and South Atlantic oyster assemblages.

Currently, the knowledge of ecology and function of bacteria harbored by molluscs is very limited. In this study, quantity and richness of culturable heterotrophic bacteria (CHB) in seawater of the farming environment and guts of the oyster Crassostrea hongkongensis were determined monthly, with classical, biochemical, and molecular methods. About 800 randomly selected bacterial strains were purified and identified.Quantities of CHB and vibrios, ranging from2.3×10³ to 2.2×10⁵ CFU/ml and 1.6×10² to 3.0×10³ CFU/ml, respectively, were present in the farming seawater, whereas those in the oyster C. hongkongensis ranged from 5.3×10⁴ to 5.4×10⁶ CFU/g and 6.0×10³ to 1.4×10⁵ CFU/g, respectively. Vibrio spp., Pseudoalteromonas spp., Bacillus spp., and Shewanella spp. appeared almost every month. Richness of heterotrophic microbial communities of the seawater and the oysters was very similar and peaked in August. Variation in the diversity (Shannon index) of CHB in the seawater and in the oysters was similar, a significant positive correlation was showed between them (r = 0.894), and their diversities were both peaked in August. Statistical analysis showed that salinity hasmore important impact on quantity of CHB in seawater. Similarly, temperature hadmore important impact on that in the oysters. Important threshold data were analyzed to further explain the relationships.

Olympia oysters (Ostrea lurida) traditionally played important ecological, economic, and cultural roles as the only oyster native to the west coast of North America. Yet overfishing, pollution, and the cultivation of nonnative oysters have driven many historic beds toward or into extinction. Restoration efforts have increased recently in an attempt to reestablish this important ecosystem engineer. In 2012, the Swinomish Indian Tribal Community began a small-scale Olympia oyster enhancement effort in two tidal lagoons with the intention of eventually establishing self-sustaining populations. To properly time future expansion efforts with peak reproductive activity, brooding status was quantified from oyster populations within both lagoons throughout the spring and summer of 2015. Brooding data were compared with water temperature and salinity. Results from this study clearly indicate that northern Puget Sound oysters located in tidal lagoons are capable of brooding at 10.5°C, two degrees colder than has been reported in the literature. Oysters in one lagoon brooded for almost an entire month before the known critical daily minimum water temperature threshold of 12.5°C was reached. These results suggest possible local adaptation or habitat-specific reproductive maturation, and are relevant for Olympia oyster restoration and expansion efforts.

Offshore oyster reefs in the Big Bend Coast of Florida have declined by 88% during the last 30 y, with the most likely mechanism being repeated die-offs due to predation and disease during high-salinity periods, driven by episodic and increasing periods of reduced freshwater input to estuaries. These die-off events have led to a conversion from shell to sandbar substrate and rapid loss of elevation (ca 8 cm/y). This process appears to be nonreversible, because oyster spat are unable to colonize sandy substrate. It is hypothesized that the addition of durable hard substrate would make reefs more resilient to periodic declines in freshwater flow by providing a persistent settlement site for extant larvae. This article reports a test of the assumption that oyster populations on these reefs are limited by substrate, and documents key effects on oysters, elevation, and avian usage associated with the addition of substrate. Durable substrate was added in the form of limerock cobbles and recycled clam Mercenaria mercenaria (Linnaeus, 1758) aquaculture bags filled with cultch, live oysters, and associated fauna to eight paired treatment and control sites spaced along a highly degraded offshore reef chain. Elevation on treatment reefs increased postconstruction by an average of 16 cm. Mean oyster density on treatment sites increased by 2.65×on rock, 14.5×on clam bags, and 9.2×overall compared with control sites. Recycled clam bags contributed approximately 25%of the surface area on treatment reefs, but accounted for 52% of the oysters observed. Oyster densities on treatment sites were between 89×and 125×those measured at a larger sample of nearby natural reefs, and exceeded the 89th percentile of reported densities at natural and restored reefs in the Gulf ofMexico. Total bird use was higher on treatment sites, but when controlled for elevation, all species but doublecrested cormorants [Phalacrocorax auritus (Lesson, 1831)] and bald eagles [Haliaeetus leucocephalus (Linnaeus, 1766)] preferred control (sand bar) sites. These results indicate that (1) oyster recruitment can be strongly limited by available, durable substrate, especially in high-energy environments; (2) aquaculture byproduct materials can play a significant role in the process of restoration; and (3) restoration of oyster reefs and other living shorelines may have impacts on avian community composition. Future research should be aimed at understanding whether durable substrate can also confer longer term resilience to oyster reef communities.

Seasonal variations in biochemical composition of the clam Dosinia corrugate were investigated from August 2013 until July 2014 in Zhuanghe Bay in relation to environmental conditions and reproductive cycle. Separate biochemical analyses of the mantle, adductor muscle, foot, and gonad-visceral mass in each sex were undertaken. Spawning took place once a year from July to August and the massive spawning occurred in August with the highest water temperature and chlorophyll a levels. Utilization of glycogen took place during the spawning period, whereas protein was biosynthesized as the mature gametes formed. The glycogen value increased during the resting stage (autumn—winter). The reproductive pattern exhibited by D. corrugate based on the storage of reserves during the period of sexual rest, and the period of gonad maturation, seems to be conservative and opportunistic. The information obtained in this study provides a basis for fisheries resource administrators to design biologically sound management measures for this species, and is crucial for initiating its aquaculture.

Growth variability has been a common feature within different Panopea species, affecting the accurate estimation of growth parameters and their theoretical trajectories. Recently, the interest in solving this problem has increased; however, the methods used for individual growth modeling of Panopea spp. have not been effective in identifying the variability within the shell length-at-age composition. In the current study, a novel approach is proposed to analyze the effect of shell length-at-age variability on the individual growth and growth parameters of Panopea globosa. The shell length-at-age data were fitted to six candidate growth models: von Bertalanffy, Gompertz, Johnson, Logistic, Generalized von Bertalanffy growth model (GVBGM), and Richards using a negative log-likelihood function. The variance for each age observed () in the population was estimated for each growth model. The best candidate growth model was selected based on corrected Akaike information criterion (AIC_c). The results indicated that the candidate growth models analyzed had different patterns of variance. The models that had the widest difference between L_∞ estimates were von Bertalanffy and Johnson growth functions. For individual growth rate parameter, the lower value was estimated for GVBGM, whereas the higher value was computed for Johnson growth model. Estimates for t₀ (age when shell length is theoretically zero) parameter only could be computed for GVBGM and Logistic growth models. The von Bertalanffy growth model showed the higher variance estimated for older individuals (), and this pattern was also observed in the variance for each age observed (), denoting growth depensation in the P. globosa population. The AIC_c indicated that the best candidate growth model was the Johnson growth model. This approach determined the best model for extracting more accurately the biological information in the shell length-at-age data. The applied methodology should be relevant for further geoduck clam population dynamics studies, providing a tool in aiding in sustainable development of these resourceimproving estimates such as yield per recruit, harvest rates, changes in biomass, and expected yield.

Razor clam species are commercially important worldwide. In Tunisia, studies on razor clams aim to promote harvesting and ensure a rational and durable exploitation. In Tunisia, Solen marginatus (Pulteney, 1799) is the most abundant razor clam species although Ensis species, particularly Ensis minor, are also found. The aim of this study is to understand the allocation strategies of S. marginatus in terms of growth and reproduction. For that, condition indices and histological analysis were performed and related to temperature and chlorophyll a. Clams were collected monthly in the southern Mediterranean Sea (Gulf of Gabes, Tunisia). Body and somatic mass increased in summer and autumn. Body condition was highest in September 2007 and the highest somatic condition index was measured in August 2008. Body and somatic mass loss occurred in winter and late spring-early summer with lowest values found, respectively, in February and May 2008. Gametogenesis rate was slow and held in a synchronous way during the cold season, leading to massive spawning and exhaustion in July 2008, and probably in June 2007. The abundant food conditions and elevated temperatures during the summer initiated a new gametogenic cycle and partial spawning events were observed in autumn 2007, after which high restoration activity occurred. The species seems to have adopted two reproductive strategies: a conservative strategy during the cold season, when food is scarce, and an opportunistic strategy during summer and autumn, when food is abundant and temperatures are high.

The present study investigated whether an acute temperature change affected hemolymph antioxidant enzyme activities and lipid peroxidation in ark shell Scapharca subcrenata transferred from 22°C to 17°C, 27°C, and 32°C for 72 h and then transferred back quickly to 22°C for a 6-h recovery period. Superoxide dismutase (SOD) and glutathione peroxidase (GPX) activities and malondialdehyde (MDA) contents [in cell-free hemolymph (CFH) and hemocyte lysate (HL)] were chosen as biomarkers of acute temperature stress. The results demonstrated that CFH and HL SOD activities decreased significantly (P < 0.05) after ark shells were exposed to 32°C for 72 h and returned to normal temperature. Glutathione peroxidase activity in CFH of ark shells exposed to 32°C increased significantly (P < 0.01) at 12 h, but then decreased significantly (P < 0.01) at the end of the recovery period. Malondialdehyde contents in the CFHandHL of stressed ark shells, regardless of temperature (17°C, 27°C, or 32°C), were lowest at 1 h of the recovery period, and recovered completely by the end of the experiment. In contrast, no difference was observed in CFH or HLMDA contents between the 17°C and 27°C groups. In conclusion, S. subcrenata had high tolerance to an acute decrease and increase in seawater temperature, but oxidative stress in ark shell hemolymph increased significantly with temperature and time, such as 32°C and greater than 72 h.

In Galicia, three venerid bivalves are exploited in the intertidal zone by local fishery guilds: Venerupis corrugata, Ruditapes philippinarum, and Ruditapes decussatus. The precise effects of the duration and intensity of high-temperature episodes on these bivalves remain largely unknown, especially when the animals are in sediment which acts as a thermal buffer. Clams in sediment were exposed to recorded summer sediment temperatures: 21°C(control), 27°C, 32°C, and 36°C(measured at 2 cmdepth in the sediment) on the diurnal low tide during three consecutive days. Burrowing activity of R. decussatus relative to temperature was a negative quadratic response, typical of performance curves where the upper limit to activity has been exceeded. The venerid bivalve V. corrugata showed evidence of sublethal stress with reduction in burrowing activity, starting at 27°C. Temperatures greater than 32°C are common on days with hot low tides on clam fisheries grounds in Galicia and are expected to increase in frequency and magnitude as the climate warms. Consistent with the sublethal response, all V. corrugata were dead after 2 days of exposure to 36°C and after 3 days at 32°C. No mortality was recorded at 21°C and 27°C. The venerid bivalves R. decussatus and R. philippinarum suffered no mortality at 21°C, 27°C, and 32°C, but had 25% and 33% mortality, respectively, after 2 days of tidal exposure to 36°C. On the basis of the results, the fishery for V. corrugata in the intertidal would appear to be most at risk due to the predicted increase of temperature, and this species would be expected to be restricted to the subtidal in the near future with negative economic consequences.

Ark shell Scapharca broughtonii is one of the most commercially important bivalve resources and is widely distributed in northeastern Asia. The aim of this study was to determine its genetic structure in Japan, China, and Korea by means of nucleotide sequence analysis of a 507-bp portion of themitochondrial DNA cytochrome c oxidase subunit I gene. Of 180 individuals collected from three localities in Japan and one locality each from China and Korea, a total of 66 haplotypes were found on the basis of 56 variable nucleotides. Although Japan and Korea populations shared six common haplotypes, there was no common haplotype between Japan/Korea and China. The pairwise F_ST and genetic distance values were comprehensively high, with significant differences between Japan/Korea and China, indicating that the divergence had reached subspecies level. In conclusion, haphazard transplantation and import of seedlings and/or adults of S. broughtonii and its related species should be absolutely avoided as S. broughtonii had previously shown distinct genetic differences between Japan/Korea and China.

Mussels are an excellent source of phytosterols, which have many health benefits including reduction of the level of cholesterol in the blood. This study examined free sterols in cultivated blue mussels obtained commercially and from laboratory feeding experiments. Mussels were fed algae or the effluent from cultured finfish for 6 mo, and others remained unfed for 10 wk. Mussels feeding on effluent is of interest for integrated multitrophic aquaculture. Fish waste-fed mussels had significantly higher cholesterol concentrations (710 mg/kg) compared with algae-fed mussels (409 mg/kg) and locally cultivated ones (321 mg/kg). Algae-fed mussels had significantly higher campesterol compared with locally cultivated and fish waste-fed mussels. In algae-fed mussels, 24-nordeydrocholesterol decreased significantly, and in fish waste-fed mussels, the concentration of 24-methylenecholesterol decreased significantly. In fish waste-fed mussels, the cholesterol proportion was 50.9% of total sterols and other beneficial sterols were 49.1%, whereas in algae-fed mussels, cholesterol was down to 36.7% and other sterols were 63.3%. In summary, fish waste-fed mussels had significantly higher cholesterol concentrations and proportions compared with locally cultivated and algaefed mussels, and algae-fed mussels had higher proportions of beneficial phytosterols than fish waste-fed mussels.

In the Gulf of Maine the rocky intertidal blue mussel Mytilus edulis (Linnaeus, 1758) is one of the most important ecosystem engineers in these communities and have been the subject of numerous physiological and ecological studies. There is now abundant support that global climate change is occurring at unprecedented rates in the GOM. In a world where multiple environmental factors vary simultaneously, we need to be able to quantify the underlying physiological, biochemical, and molecular changes that lead to emergent properties of the organism (e.g., growth, reproduction, mortality) in key species like intertidal mussels. Here, we provide transcriptomic resources for both the gill and adductor muscle of blue mussels from the GOM. Of the full complement of transcripts (n = 57,718), 56,655 were expressed in the gill and 53,081 were expressed in the adductor muscle with 4,489 and 915 transcripts expressed uniquely in the gill and muscle, respectively. The putative transcripts for M. edulis were assigned to 617 genes for gill and 178 genes for adductor muscle and clustered into 12 functional categories, including those in well-known stress pathways. These transcriptomes can be used to test important hypotheses on gene regulation, phenotypic plasticity, mechanisms of physiological resilience, and local adaptation in response to climate change stressors (i.e., thermal stress and ocean acidification).

The seasonal variation and spat recruitment pattern of the scallops Flexopecten glaber and Chlamys varia in the protected aquatic ecosystem of the northwestern Amvrakikos Gulf (Natura, 2000) were examined by using a combination of plankton sampling and spat collection techniques during the spring and summer of 2007. The presence of the larvae was reported in all samples from the beginning of May to the end of August. Peak numbers were obtained at the beginning of June and in mid-July. The highest settlement density was recorded at a depth of 8 m below the surface, indicating the most suitable placement for the spat collectors despite the hypoxic bottom layer underneath.

The U.S. Atlantic sea scallop fishery has a bycatch allocation of Georges Bank yellowtail flounder that has in some cases limited the ability of the scallop fleet to fully optimize harvest of the scallop allocation. One strategy used to mitigate bycatch in the Georges Bank sea scallop fishery is time/area closures of scallop access areas. The original access area closure period, established in 1999, ran from February 1 through June 15, and it was primarily based on historical yellowtail spawning data at a broad spatial resolution. Beginning in 2011, data on yellowtail bycatch rates in the scallop fishery were collected during a dedicated seasonal bycatch survey in and around the scallop access areas of Closed Area I and Closed Area II on Georges Bank. Examination of seasonal trends in this data resulted in managers eliminating seasonal closures starting in 2013 in the Nantucket Lightship and Closed Area I access areas, and changing the dates for the seasonal closure in the Closed Area II access area to August 15 through November 15. This cooperative, fishery-independent seasonal bycatch survey has been an effective tool for monitoring seasonal variability in bycatch and informing time/area closures.

Performance and stress resistance of juvenile abalone (Haliotis discus) fed formulated diets substituting fish meal (FM) and macroalgae (MA) with soybean meal and rice bran, respectively, was compared with the MA under various stress conditions. Four experimental diets (Standard, FM50, FM50 MA50, and FM50 MA100 diets) were prepared in duplicate. The dry MA (Undaria pinnatifida and Laminaria japonica)were also prepared to compare with the effects of formulated diets on the performance of abalone to achieve the industry standard. About 84,000 juvenile abalone were distributed into twelve 5-ton tanks (7,000 abalone per tank). The diets were fed to abalone once a day to satiation. At the end of the 16-wk feeding trial, abalone were subjected to various stress (air exposure, sudden salinity, and temperature changes) conditions and cumulative mortality was monitored. Weight gain and specific growth rate of abalone fed the all formulated diets were higher than the dry MA. The cumulative mortality of abalone fed the MA was higher than that of abalone fed the all formulated diets at the end of observation after sudden salinity and temperature changes. In conclusion, the well-formulated diets produced better growth performance of abalone over the dry MA. Abalone subjected to the various stress conditions after being fed with all formulated diets, except for abalone fed with the Standard, FM50, and FM50 MA50 diets after air exposure, were more resistant than those fed the MA.

Queen conch (Lobatus gigas) populations living deeper than 20 m are rarely studied, because of the limitations of conventional survey methods using divers [i.e., belt transect (BT), towed-diver]. Acrucial management goal for conch populations is to maintain adult densities at adequate levels to ensure reproduction, which is highly density dependent. Therefore, accurate estimates of adult conch densities, both in shallow and deep areas, are essential. The rapid technical progress of video systems has made it possible to develop new cost-effective ecological sampling tools, which can be used to survey areas previously hardly accessible. A lightweight towed video array was used, which was able to survey adult conch throughout the species entire depth range (ca. 0–60 m depth), in a safe and efficient manner. The towed video method (TVM) was compared with a conventional BT method using scuba divers, in its ability to identify adult live and dead conch. A series of intercalibration transects was conducted in a high-complexity (HC) and in a low-complexity (LC) habitat by having the towed video followed by a diver conducting a concurrent standard BT, covering the exact same surface area as the towed video. In both the HC and LC habitat, adult live queen conch had similar counts with both methods. Adult dead conch were not mistaken for live conch but were significantly underestimated with the towed video compared with the BT. The results validate the use of TVM as a reliable sampling tool to estimate densities of live adult conch in both HC and LC habitats throughout the species depth range.

The muricid gastropods Concholepas concholepas (loco or false abalone), endemic to Chile and Peru, and Haliotidae Haliotis spp. (abalone) are highly priced seafood delicacies traded in Asian markets. Historical catches, management strategies, production, prices, and revenues are analyzed for these wild and farmed gastropods. Wild abalone prices have a positive effect (P < 0.01), landings a negative effect (P = 0.01), and farmed aquaculture production a negative effect (P = 0.09) on Chilean loco export prices. This underscores the high degree of market integration and the direct price relationship for these gastropods between Chilean and the Asian seafood markets. Drops in the Chilean export prices of locos had a negative effect on official loco landings in Chile, affecting the small-scale territorial user rights for fishery comanagement scheme developed for the species. The study shows evidence of distal connections (telecoupling) between production and market forces, that can jeopardize fishery management efforts. Aquaculture being developed in certain parts of the world can impact quite specifically on the attempts to achieve sustainable fisheries in other geographically distinct areas. Because of large market fluctuations, and a global drive to develop large-scale farming of marine gastropods, there is an urgent need to strengthen the adaptive capacity for diversification, and to add value to resources, so as not to hamper the long-term development of traditional coastal fishing communities.

The Deepwater Horizon oil spill in the spring/summer of 2010 occurred during the peak spawning season of the blue crab Callinectes sapidus in the northern Gulf of Mexico. The potential for contamination of larvae by crude oil and dispersants associated with the spill was high given the life history of blue crabs. The oil spill occurred in offshore waters considered important for blue crab larval development and there was high spatial and temporal overlap between blue crab larvae and the incident area. Exposure to contaminants may have occurred in both the offshore developmental phase and the nearshore settlement stage. Fluorescence spectroscopy techniques were developed to detect polycyclic aromatic hydrocarbon contamination in composite samples of tissue of 50 megalopae. Samples as low as 400 µl were analyzed allowing for detection of contaminants in very small sample sizes. Evidence of petroleum contamination was found in all megalopae harvested from the wild.

Knowledge of short- and long-term reproductive patterns is basic for numerous types of biological, ecological, evolutionary, and fisheries studies. Using data from more than 22 y of sampling commercially valuable stone crabs (genus Menippe (Say, 1819)) in Tampa Bay, FL, we defined size-specific interannual and intra-annual patterns in ovarian development and spawning; explored relationships between the molting cycle and intra-annual patterns; and identified the influence of water temperature on those interrelationships. Frequency of gravid females (frequency-gravid) seemed to shift in multiyear cycles but frequency of ovigerous females (frequency-ovigerous) did not. Frequency-gravid and frequency-ovigerous increased with size class except in the largest females. Interannual variation in frequency-ovigerous was the product of multiple patterns differing principally between size-class-70 and -80 females and size-class-90 and -100 females. Ovarian development, spawning, and molting in females of size classes 20 through 50 occurred principally during peak temperatures in August and September. In females of size classes 70 through 100 , ovarian development, which was tightly and inversely linked to molting, occurred principally from February through August and spawning, which was influenced by both water temperature and molting, occurred principally from April through September. Size-class-60 females exhibited a mosaic of juvenile and adult patterns. Ovarian development and spawning ceased in all size classes when temperature decreased to approximately 25°C during October. Other specific temperatures or narrow temperature ranges were associated with additional shifts in reproduction and molting. Decreases through the years in frequency-ovigerous in females in size classes greater than or equal to 70, and particularly in those in size class 100 , concomitant with increases in frequency-ovigerous in females in size classes 50 and 60, and coupled with possible decreases in size at maturity and minimum spawning size, suggest fisheries selection. Shortening harvesting season by 6 wk during spring would protect females during the first spawning pulse in spring.

The brown crab is an important fishery resource in northern Europe. Understanding factors that affect fecundity in this species is complicated by the fact that ovigerous females enter traps infrequently. This study aimed to understand factors that affect brown crab fecundity and egg quality for crabs sampled from the waters around the Isle of Man. The size-fecundity relationship for the Isle of Man matched closely with those published for other geographical areas where a fishery exists for this species. Ovigerous crabs varied in size from 134 to 215 mm carapace width and each individual carried an estimated 0.4–3.0 million eggs. Fecundity was not affected by factors such as sampling season, location, loss of chelae, or black spot disease. Egg volume was independent of the number of eggs per batch or female body size. Egg volume was reduced significantly in crabs that had lost chelae. Egg dry weight, C and N composition did not vary with body size or any other explanatory factors such as chelal loss or the occurrence of black spot disease. Although the importance of the effect of claw loss on egg volume remains unclear, it may be an important consideration in fisheries in which the landing of claws is permitted.

Blue crab (Callinectes sapidus) landings along Atlantic and Gulf of Mexico coasts have been decreasing for several years. Given the euryhaline nature of blue crabs, culture in inland ponds may provide a means of meeting demand. The goal of this study was to develop an ionic environment containing 1 g/l total dissolved solids (TDS) that would support the survival and growth of juvenile blue crabs. The 1 g/l TDS level was selected to minimize the cost of preparing ponds, and potentially to reduce the need for effluent permitting in inlands areas. The general approach was to provide selected ions in approximate concentrations found in 1 g/l dilute seawater. In a series of four 3-wk experiments, beginning with ∼20-mm carapace width crabs, it was observed that blue crabs can survive and grow in a simple aqueous solution containing 1 g/l TDS (0.445 g/l sodium chloride, 0.120 g/l sodium sulfate, 0.022 g/l potassium chloride, 0.045 g/l calcium chloride dihydrate, 0.349 g/l magnesium chloride hexahydrate, 0.133 g/l sodium bicarbonate, and 0.002 g/l strontium nitrate), and this growth is equivalent to that of crabs in 1–8 g/l dilute seawater. It was further observed that blue crabs in 1 g/l TDS aqueous solution are susceptible to environmental nitrite with an average of 49% (range = 17%–85%) of crabs dying after exposure for 5 days to a nominal 2 mg/l nitrite-N in 26°C water. This work indicates that blue crab culture in inland ponds containing 1 g/l TDS may be feasible.

Organic acids are receiving increasing attention as a potential means to improve the growth as well as nutrient utilization of aquatic animals. A 20-day experiment was conducted to compare the effects of different dietary organic acid salts that included sodium acetate, sodium citrate, sodium butyrate, or sodium propionate at 2%, on the survival, growth, and hepatopancreatic histopathology of blue swimmer crab Portunus pelagicus early juveniles. All diets were isonitrogenous and were provided to apparent satiation twice daily. Crabs were kept individually within plastic containers, and there were 45 replicate crabs for each treatment. Results showed that, by the third molt, all the tested dietary organic acids significantly (P < 0.05) accelerated the molting (7.16–8.65 days) of the crabs compared with those in the control treatment (10.03 days). The specific growth rate (SGR) for width and length as well as the final dry weights were significantly higher (P < 0.05) in all the organic acid treatments, while SGR for weight was significantly higher (P < 0.05) in the sodium acetate and sodium propionate treatments, compared with the control. Hepatopancreatic histopathology revealed no structural differences in all treatments or staining intensity for glycogen. To our knowledge, this is the first reported study showing improvements to the survival and growth of crabs fed with inclusions of dietary organic acids.

A previous survey reported that swimming crabs Portunus trituberculatus (Miers, 1976) in the East China Sea may have a low risk of sperm limitation under the current nonselective fishing practices. In this study, the possible mechanism of avoiding sperm limitation was investigated in a mating season (from July to November 2007) from a male perspective. Males reached 50% gonadal maturity at a carapace length of 99.4 mm and the reproductive measures (vas deferens weights, sperm number, and sperm concentration retained in the vasa deferentia) did not differ significantly throughout the mating season. As shown for other decapods, the quantity of seminal material in the vasa deferentia increased significantly with male size, without a concomitant change in sperm concentration. The proportion of stored sperm transferred at a single mating was calculated, and the results showed that males exhibited low sperm transfer at each mating, regardless of size. These findings indicate that the current fishery practices for P. trituberculatus may have little impact on the quantity of sperm stored by males throughout the mating season. This would guarantee that males of all sizes retain the capacity to mate throughout the breeding season, and, moreover, provide sufficient sperm to fertilize eggs spawned by their mates and reduce the risk of sperm limitation under the current fishing practices in the East China Sea.

Hemocyte types of the Macrobrachium prawn Macrobrachium rosenbergii were identified using the methods of flow cytometry and light microscopy. The activities of endoenzymes including peroxidase (POD), phenoloxidase (PO), and alkaline phosphatase (ALP) in hemocytes were analyzed by cytochemical and biochemical methods. Mitochondrial membrane potential (MMP) of the hemocyte was probed according to the accumulation of the cyanine dye, 3′, 3′-dihexyloxacarbocyanine iodide, in the mitochondrial matrix. The results showed that there were three types of circulating hemocytes (hyalinocytes, semigranulocytes, and granulocytes) in M. rosenbergii. Enzymes POD, PO, and ALP were more abundant and active in granulocytes and semigranulocytes than in hyalinocytes. The data associated with MMP showed that the fluorescence intensity in the hemocyte was directly correlated to cell complexity. The MMP in granulocytes was significantly greater than that in semigranulocytes, and the latter was significantly greater than that in hyalinocytes.

The authors regret that the following errors were in the published paper:

In the affiliations, “United States Geological Survey” should be changed to “U.S. Geological Survey”.

In the Methods section “Additional animals were obtained from a colony maintained at the USGS Wetlands Center;” should be changed to “Additional animals were obtained from a colony maintained at the USGS Wetland and Aquatic Research Center;”.

In the Methods section “All DNA sequences have been deposited in the National Center for Biotechnology Information GenBank (see Table 1).” should be changed to “All DNA sequences have been deposited in the National Center for Biotechnology Information GenBank.”