Scallops swim using jet propulsion produced by expulsion of water from between the valves by rapid contraction of the adductor muscle. The valves are subsequently opened by a ligament that acts like a spring mechanism. Compared with burrowing or sessile bivalves, scallops have ligaments with greater resilience. To determine whether the ligament resilience, ligament opening force, and force deployed by the phasic and tonic adductor muscles varied with escape response strategies and shell morphology, these properties were compared in scallops (Amusium balloti, Placopecten magellanicus, Equichlamys bifrons, Pecten fumatus, Mimachlamys asperrima, and Crassadoma gigantea) with differing life habits and morphologies. The ligament opening force varied among species and was always equal to or exceeded by phasic and tonic closing forces. The species producing the greatest frequency of phasic contractions (P. fumatus) had the greatest ligament resilience.

A high mortality of the Yesso scallop Patinopecten yessoensisis (Jay, 1857) larvae occurred during the seedling process: the larvae lost their ability to swim, their cilia fell off and their valves closed, they then sank to the bottom of the nursery pond and died. Total viable vibrio's counts in moribund larvae were 1.1 × 10⁴ colony forming unit/g on tryptone-citrate-bilesucrose agar plates. Two dominant strains, named V1 and V2, accounted for 64.3% and 32.1% of total vibrios counts, respectively. Strain V1 exhibited beta hemolysis, whereas V2 exhibited alpha hemolysis. A challenge test showed that the signs of infected larvae were identical to those of natural moribund larvae, and the cumulative mortality caused by strains V1 and V2 was significantly higher than that of the control (P < 0.05). Strains V1 and V2 shared 99.9% and 99.2% identity with Vibrio splendidus ctt 31/5 and Vibrio tasmaniensis 007, respectively, by 16S rDNA sequencing. The presence of genes coding for virulence factors was examined by PCR analysis, showing that strain V1 possesses the extracellular metalloprotease (vsm) gene. In this study, strains V1 and V2 were demonstrated to be pathogens causing mortality in Yesso scallop larvae.

Planting oyster cultch is a common management approach used to enhance recruitment. The two most popular cultch materials are shell and limestone. Both are sold by volume or weight; however, once deposited on oyster grounds, only a small portion of the total surface area of each particle is available for recruitment. Shell and limestone have different surface area to volume properties, and thus provide differential settlement opportunities. Exposed surface area to volume (expSA/V) ratios of oyster shell and limestone fragments were compared, as an indicator of their recruitment potential and cost-effectiveness for cultch planting. Samples were collected from the Primary Public Oyster Seed Grounds in Louisiana by vibracore, and from the Pass Christian TongingGrounds in Mississippi by dredge. Shell (including whole shell and fragments) and limestone particles greater than or equal to 8 mm by geometric shape were classified and their expSA/V was calculated. Mean expSA/V ratios of shell were approximately three to nine times higher than limestone. For limestone of similar particle size to provide an equivalent recruitment benefit for the same cost would require that the cost of purchase, transport, and planting be three to nine times lower than shell. Thus, shell is likely to be a more efficient material than limestone for recruitment enhancement. Nevertheless, the higher variability in expSA/V of shell and other factors such as the expected lifetime and the relative performance of small and large particles of materials should also be considered. Analysis of a Louisiana limestone plant and associated oyster cultch showed that the proportion of small and large limestone particles and the relative proportion of whole shells and fragments can greatly alter expSA/V. In this case, the a priori expectation that oyster shell would outperform limestone did not materialize because of the quantity of small limestone particles of favorable shapes in the deployed material. Even so, as yet unknown is the possible reduction in performance in situ of smaller particles that might occur if they increase the one-dimensionality of the plant.

Conservation paleobiology aims to apply data from geohistorical records, such as fossils and their associated sediments, to the conservation of biodiversity and ecosystem services. Integrating geohistorical data into conservation/restoration practice, however, has proved difficult. To better understand how geohistorical data can be more effectively integrated into the conservation/restoration of an ecologically, economically, and culturally important group—oysters—a web-based survey was conducted to assess the awareness and understanding of geohistorical data and perspectives on their use in restoration among oyster researchers and restoration practitioners in the United States. The 97 survey responses not only demonstrate overall willingness to use geohistorical data in oyster restoration but also highlight knowledge gaps. For instance, although many respondents understood some uses for geohistorical data, e.g., providing baseline information, few respondents mentioned others, such as reconstructing historical ranges of variation of ecosystem attributes. Respondents were also generally not aware of the full range of restoration metrics that can be measured from geohistorical records. The responses further suggested how geohistorical information might both reinforce and expand the information currently available to oyster restoration professionals. For instance, only half of respondents indicated that their baseline information predates the 20^th century, but geohistorical records of oysters can provide data on timescales ranging from decades to millennia. Finally, it is argued that to raise awareness of this underutilized information and address respondents' doubts about the completeness, precision/accuracy, and relevance of geohistorical data in a rapidly changing, human-dominated world, increased collaboration between conservation paleobiologists and conservation/restoration scientists is needed.

Restoration of the native eastern oyster (Crassostrea virginica) has been severely hindered by the dwindling supply and rising costs of fossil and new oyster shell (OS) for use in reef restoration. Consequently, emphasis has shifted to the use of alternative oyster reef materials, which need to be tested for their effectiveness as settlement substrate. Furthermore, low recruitment of wild larvae has also impeded restoration, indicating a need to assess the potential of field setting of cultured larvae. We experimentally examined oyster settlement, growth and survival on unconsolidated OS, vertically embedded oyster shell (ES) in concrete, and concrete Oyster Castles (OC) in field and mesocosm experiments. In addition, we examined settlement success of cultured larvae in the mesocosm experiment. In the field experiment, juvenile recruitment was 3× higher on castles and unconsolidated shell than on embedded shell. Castles retained 4× the number of oysters and hosted 5× the biomass than embedded shell, and retained 1.5× the oysters and hosted 3× the biomass than unconsolidated shell. The proportion of live oyster recruits on castles was 1.5× that on both embedded and unconsolidated shell. In the mesocosm experiment (90-d postlarval deployment), the castles recruited, retained, and hosted an oyster biomass 4× higher than that of unconsolidated and embedded shell. This study confirms that artificial reef materials, such as OC, are suitable alternative substrates for oyster restoration, and remote setting of larvae can be effective under controlled environmental conditions. Future restoration efforts should consider use of alternative reef substrates and field setting of larvae, where recruitment is limited, to maximize oyster recruitment, while simultaneously minimizing the cost of reef restoration.

Globally, 85% of shellfish reefs have been lost during the past century. The severe loss of the eastern oyster Crassostrea virginica has encouraged different types of restoration efforts in the United States. In Mosquito Lagoon (ML), a shallow-water estuary on the east coast of central Florida, restoration focuses on providing additional substrate for larval recruitment via deployment of stabilized oyster shell. To assess the current number and area of natural, dead, and restored oyster reefs within ML, aerial photographs from 2009 were digitized using ArcGIS software. All reefs were screen digitized using a reef “signature” to estimate the surface area of each reef type. The maps from 2009 were then used as a guide to digitizing the historical aerial photographs (1943, 1951, 1967, 1971, 1984, 1995, and 2006). Oyster habitat within ML has decreased by almost 15 hectares between 1943 and 2009, which constitutes 24%of the 1943 lagoon-wide coverage. The impacts were greater in Canaveral National Seashore,which covers the southernML; 40%of the oyster coverage within the park has been lost since 1943. Dead reefs were found adjacent to important boating channels. Tracked dead reefs exhibited a continuous migration into the mangrove islands located landward of the original live reefs, with some dead reefs completely washing up into the marsh. Restoration of dead reefs with stabilized oyster shells has added nearly 1 hectare of live oyster habitat toML as of January 2009. This research demonstrates that dead reefs are increasing in number and coverage within ML, but this trend can be reversed with restoration.

This article reviews recent literature on the biology of Ostrea lurida, emphasizing information that has arisen subsequent to Baker's review in 1995. The review highlights recent work that contributes to improvements in restoration efforts. Included are sections on phylogeny, reproductive biology, shell morphology, harvesting, associations with other organisms, threats to recovering populations, ocean acidification, and larval supply, settlement and recruitment.

With an annual production of 1500 metric tons of shucked oysters, Willapa Bay, WA currently produces more oysters than any other estuary in the United States. This production is mainly composed of the Pacific oyster (Crassostrea gigas), rather than the native Olympia oyster (Ostrea lurida). Historically, Willapa Bay was home to vast Olympia oyster beds, which formed the foundation of a major extractive fishery in the late 1800s. Yet the historical baseline extent of this habitat is poorly understood as it was first documented following decades of exploitation and was therefore based on a shifted baseline. An extensive and thorough literature review was undertaken to ascertain whether oyster beds mapped as “cultivated” in the 1890s were in fact originally wild beds. The most complete harvest statistics to date have been presented for the Olympia oyster in Willapa Bay (from 1849 to 2011) to provide useful historical insights into the expansion and collapse of the Olympia oyster fishery and discuss the evidence for numerous drivers of decline. Compelling evidence found that the historical extent of oyster beds in Willapa Bay may have been as great as 9774 ha, or 27% of the bay bottom, equating to a standing oyster biomass on the order of 3.6 × 10⁶kg. This figure is significantly greater that the often quoted ∼2600 ha, derived if only beds marked as natural in the 1880s and 1890s are considered part of the original extent.

The oyster pea crab Zaops ostreum (Say, 1817), is a parasite of the eastern oyster Crassostrea virginica Gmelin (1791). This study examined the frequency of occurrence and impact of pea crabs on adult (50–70 mm shell height [SH]) oysters from natural intertidal reefs in Hewletts Creek, Wilmington, NC and artificially created intertidal reefs from Jones Island, NC. The reefs at Hewletts Creek and Jones Island were also sampled in the fall of 2012 to quantify the presence of pea crabs in two cooccurring bivalve species, the scorched mussel Brachidontes exustus (Linneaus, 1758), and the ribbed mussel Geukensia demissa (Dillwyn, 1817). To evaluate the impact of pea crabs on juvenile oysters (mean SH 11.07 ± 0.16 mm), oysters were deployed in Hewletts Creek at three densities during July 2013 and then retrieved in October 2013. The percent occurrence of pea crabs in adult oysters was low on the natural reefs (1%–3.7%), greater on the created reefs (10%), whereas the percent occurrence in the deployed juvenile oysters ranged from 22.5% to 27.6%. The condition index of oysters from all treatments was significantly reduced (P < 0.05) in the presence of a pea crab; however, pea crabs did not influence (P > 0.05) oyster SH—length ratios. Juvenile oyster densities did not influence (P > 0.05) the incidence of pea crabs, although carapace width of pea crabs increased (P = 0.05) with decreased densities. On the naturally occurring reefs, pea crabs were found in scorched mussels (2.5% incidence) and ribbed mussels (2.0% incidence), but on the created reefs at Jones Island, pea crabs were only found in ribbed mussels (2.0% incidence). Results of this study highlight the impact of this parasite on the host oyster and the potential of this parasite to infect a significant portion of the younger oyster population, which may influence oyster population dynamics, as indicated by low infestation rates in adult oysters. This study also provided a quantitative foundation for understanding the prevalence of pea crabs in alternative hosts, as the pea crab population may be underestimated if multiple hosts are used.

The production of native oysters Crassostrea rhizophorae and Crassostrea gasar is expanding in northeastern Brazil, where reports of bivalve pathology are scarce. Recently, Perkinsus marinus was detected for the first time infecting C. rhizophorae in the state of Paraíba, in northeastern Brazil. Thus, more information on factors affecting the health of oysters is needed, especially concerning the pathogens listed by the World Organisation for Animal Health (OIE). The current study evaluated the health status of wild and cultured C. gasar mangrove oysters from the estuary of the Rio São Francisco, Sergipe state, northeastern Brazil. Results show that C. gasar oysters cultivated in the Rio São Francisco estuary had a greater prevalence of diseases and pathogens than oysters from a natural population in the same estuary, including maladie du pied (shell disease), Rickettsia—like organisms in gills, Steinhausia sp. oocyte infections, and Polydora sp. valve infestations. Of the two OIE notifiable diseases investigated, perkinsosis occurred at variable levels of prevalence that were always greater among cultured oysters (50.8%) than wild oysters (25.8%), and the intensity was predominantly low, suggesting low mortality impact. Bonamiosis was not detected.

Massive mortalities of eastern oysters Crassostrea virginica were observed in 1984 and 1985 along Connecticut's shoreline in Long Island Sound. An archived collection of histological slides was discovered which contained sections of oysters sampled for the late Dr. Sung Feng at the University of Connecticut in response to the oyster mortality event. Oysters from the Hammonasset River, East River, Tom's Creek, and Pawcatuck River were collected for histopathological examination between June of 1986 and December of 1987. A reference sample was collected from Mecox Bay on the Atlantic shore of Long Island, NY. The slide collection consisted of 781 oysters, 59 of which were gapers. Examination of the slides, performed decades later, revealed an epizootic of Haplosporidium nelsoni. The highest prevalence of H. nelsoni occurred in the Hammonasset River in June of 1987 with a 52% prevalence.No H. nelsoni was detected in the reference sample from Mecox Bay, NY. While H. nelsoni plasmodia were detected in 41% of the gapers, 80% of had a terminal infection. Dr. Fengs's archived slide collection demonstrates a wide-spread H. nelsoni epizootic in the mid-1980s in Long Island Sound and establishes the involvement of H. nelsoni in the observed oyster mortalities.

The feasibility for rapid determination of the chemical composition of Pacific oyster (Crassostrea gigas) by near IR reflectance spectroscopy (NIRS) was assessed. NIRS calibration models were developed using 118 sets of C. gigas samples (two to three sets per batch, total of 54 batches, 5–10 individuals per set) collected over 10 mo from seven coastal locations in northeast China. Glycogen, protein, fat, taurine, zinc, selenium, and ash contents of gonad-visceral mass and adductor muscle were analyzed by laboratory-based methods. Freeze-dried samples were scanned by NIRS at 10,000–4,000 cm^-1 and their chemical composition was predicted by partial least squares regression. Results showed that the correlation coefficient of calibration (R_C) was greater than 0.90 for most chemical components tested (except taurine, 0.8266). Similar differences were found in the correlation coefficient and other parameter indices in both cross and external validations for various chemical components. This study indicates that NIRS provides a rapid and accurate method for rapidly determining glycogen and protein contents in oyster meat (R_C = 0.9917–0.9927). The NIRS method is feasible but slightly less accurate for quantifying fat, zinc, selenium, and ash contents in C. gigas (R_C = 0.9164–0.9529).

Metallothioneins (MT) play important roles in trace metal homeostasis as well as excess metal detoxification in all organisms. They have been acknowledged as the most valid biomarker to indicate metal exposure in both vertebrates and invertebrates. In this study, the coding sequence of MT of a mollusk, the oyster Crassostrea hongkongensis, was determined by molecular cloning. The derived peptide sequence is composed of 75 amino acid residues of high cysteine content (28%). Blast analysis indicated that the MT gene in C. hongkongensis shares high homology with the MT genes of other aquatic invertebrates. The prokaryotically expressed ChMT protein was purified and used as antigen in the development of polyclonal antibodies, allowing the quantification of ChMT expression by competitive enzyme-linked immunosorbent assay in various tissues of the oyster on CdCl₂-stressed conditions. Clear inductions of MT expression were observed in the digestive gland, gills as well as mantle by CdCl₂ at a concentration of either 100 or 300 µg/l, notably from 24 h to 8 days posttreatment. Indicating a dosedependent manner, CdCl₂ in 300 µg/l scale always led to more pronounced MT enhancement. The MT induction profile covered three stages of accumulation, gradual decline, and sharp decline, which likely indicates the differential physiological states of C. hongkongensis on continuous cadmium exposure. Our study demonstrates for the first time that the MT in C. hongkongensis could potentially respond to the presence of Cd in aquatic environments, and developed a practical approach that can efficiently and specifically detect ChMT from the oyster tissues. The ChMT induction profile on high level of Cd highlights the relationships between MT inducibility and the cellular compensatory and/or toxic responses.

Production of larger, rounder, high-quality cultured pearls with fewer circles is one of themain challenges of Pinctada margaritifera aquaculture faced by every pearl farm in French Polynesia. Although bigger pearl sizes can be achieved through surgreffe operations (implantation of a second nucleus after pearl harvest), control of the development of pearl circles and shapes still remains unclear, as illustrated by grafter's empirical rules, where often the surgreffe process is only performed after production of uncircled and round pearl shapes. The present study was designed with a real pearl by pearl traceability to reveal for the first time the development of circles and shapes from graft and surgreffe, in relation to the size of the pearl sac. This was indirectly assessed by measuring the differences in diameter (DD) and weight (DW) between standardized surgreffe nuclei and the pearl that had been harvested after the initial graft.An experimental graft and surgreffe experimentwas designed using the same criteria: grafter, location, nuclei brand and size for graft and surgreffe, and donor oysters from 10 biparental families produced in a hatchery system.We studied the differences between pearls harvested after graft and surgreffe on the same recipient oysters (n=295 for both graft and surgreffe) in relation to three classes of DDand DWin which the surgreffe nuclei, were: (1) bigger/heavier, (2) equivalent to, or (3) smaller/lighter than the harvested pearl. Results revealed that to increase the rate of uncircled pearls after surgreffe, insertion of a nucleus larger than the harvested pearl may be advisable. Indeed, the formation of uncircled pearls after surgreffe was enhanced by inserting bigger/ heavier second nucleus, both in animals that had produced a uncircled pearl after the initial graft and in those that had produced a circled pearl. For pearl shape, significantly more round shape pearls were produced after surgreffe, after initial oval and baroque samples from graft, by inserting smaller/lighter and bigger/heavier second nucleus, respectively. Inserting a larger second nucleus will significantly increase the rate of both uncircled and round-shaped pearls. This finding has important implications for surgreffe practices, where recipient oysters with undesirable circle or baroque pearls could now be used in this second stage of production.

The recent resurrection of a Tridacna maxima sensu Rosewater (1965) ecotype as a distinct species, Tridacna noae (Röding, 1798), has raised concerns that inadvertent confusion of the two species in the past may have led to overestimates of T.maxima densities and errors in determining demographic parameters. To assess the potential impacts of such a scenario, this study examined the population demographics of T. noae within the center of its geographic distribution in the Kavieng lagoonal system of New Ireland Province, Papua New Guinea. The study found that 42% of the T. maxima sensu Rosewater population could be delineated as T. noae, with T. noae being the most abundant giant clam species at 7 of the 20 study sites. Past confusion of the two species is likely to be of the greatest concern on reef sites with high or medium levels of exposure to oceanic influences where T. maxima (2.08 ± 0.41 per 400 m², 1.86 ± 0.59 per 400 m², respectively) and T. noae (2.06 ± 0.36 per 400 m², 1.25 ± 0.28 per 400 m², respectively) densities were similar (P > 0.05). In analyzing size (shell length) frequency distributions, it was determined that the T. noae population had a larger mean size (206 ± 6 mm) than that of T. maxima (161 ±6 mm, P < 0.001). Thus, in areas where the two species have overlapping distributions and fisheries regulations are based on size, reassessment of T. maxima stocks should be considered a priority given the high frequency at which the larger T. noae may comprise historical populations of T. maxima sensu Rosewater.

In this study, the gametogenic cycle of the newly introducedManila clam Ruditapes philippinarum was described for the first time for Turkish waters and compared with that of the native European grooved carpet shell clam Ruditapes decussatus coexisting in Çardak Lagoon (Çanakkale, Turkey) in the Dardanelles. A total of 480 individuals were sampled for each species between January andDecember 2011. Both species exhibited similar distinct seasonal changes in gonad activity and completed their gametogenic cycles. In both species, gonads advanced very fast after winter reaching ripe stage in April and May in theManila clams and carpet shell clams, respectively. In Manila clams, spawning commenced in April and continued until October. In carpet shell clams, spawning started in May, but the main spawning event occurred in June and continued until July with a discontinuation in August and a marginal spawning taking place in September and possibly in October. Gonad index (GI) values were indicated similarities in gonad development between males and females of both species with apparent synchronism between sexes during early development, first maturation and early spawning until July. We report for the first time the reproduction of the Manila clam in Turkish waters and show that optimal conditions for gametogenesis and spawning exist for this exotic species from March until October in the Dardanelles. This information will be useful for clam fishery management especially in areas where carpet shell clam and the Manila clam are known to coexist.

The growth, reproduction, and density of warty venus clams (Venus verrucosa) were studied at a depth of 2–5 m in Baklaburnu Bay in the North Aegean Sea, Turkey. Samples were collected monthly between September 2012 and August 2013. The average density of the studied population ranged between 152 individuals m^-2 (October) and 310 individuals m^-2 (June). The shell length at first capture (L_50%) by hand rake was 37 mm. von Bertalanffy growth parameters using the length—frequency distribution of V. verrucosa were estimated at L_∞ = 57.65 mm, the rate at which the asymptotic length (L_∞) is approached (K) = 0.25 y^-1, theoretical age (y) when the length = 0 (t₀) = -0.211, and seasonal oscillation in the growth rate was 0.30. Growth was rapid during the first 4 y of life (∼40 mm) and decreased after the 4^th y. The slowest growth period was in January (winter point = 0.03). Overall growth performance, growth performance index, and potential longevity derived from seasonal parameters were calculated as 4.68, 2.92, and 12.0 y, respectively. The growth pattern showed isometric growth (slope [b] = 3.09) and the spawning period occurred from mid-June to August.

The northern hard clam Mercenaria mercenaria is one of the most commercially important bivalve species produced via aquaculture in the eastern United States. Breeding practices associated with large-scale hatchery production of hard clam seed may result in unintended, potentially negative consequences including inbreeding and reduced levels of genetic diversity. Seven microsatellite markers were used to compare levels of genetic diversity in six hatchery stocks and four wild stocks from the state of Florida. Wild stocks of M. mercenaria had slightly higher levels of allelic richness and similar observed heterozygosity (wild = A_r = 3.61,H_o = 0.448; hatchery = A_r = 3.46,H_o = 0.452); however, these differenceswere not statistically significant (A_r: P = 0.145; H_o: P = 0.931). Differentiation was highest between hatchery stocks (G_ST = 0.03, SD = 0.007; P < 0.001) but minimal among hatchery-by-wild comparisons. In contrast, wild stocks were not differentiated (G_ST = -0.002, SD = 0.004; P ≈ 0.58) and Bayesian comparisons of competing gene flow models (panmixia, stepping stone, and full-migration) suggested that wild stocks were effectively panmictic at this scale. Together, these results indicate that some genetic drift has occurred within hatchery populations, possibly as a result of broodstock selection and spawning practices. The genetic divergence between wild and hatchery stocks observed in this study are not as pronounced as seen in other aquaculture bivalve species. Given the large scale of hard clam production in Florida we argue that hatchery practices should incorporate long-term genetic goals (i.e., avoidance of inbreeding) to maintain the integrity of hatchery stocks. A secondary objective of this study was to amplify a congeneric species, Mercenaria campechiensis, using the same suite of microsatellite markers to assess their utility for detecting interspecific hybridization. Amplification success was poor and failed for four of the seven loci. The identification of microsatellite loci for different species of Mercenaria should be identified de novo in the future.

The razor clam Ensis macha (Molina, 1782), is an important resource, which has been overfished, and is now starting to be cultivated. As there is no baseline information on parasites of this bivalve, a histopathological assessment of broodstock was undertaken. Sampling of a total of 128 razor clams was carried out in March, May, September, and December of 2014, to analyze the presence and identification of possible parasites. The razor clam tissues were routinely processed for histology, observed under light microscopy, and photographed. The results showed the presence of rickettsiales-like organisms (RLO) in the epithelium of the digestive gland, ciliates, and unidentified coccidia in gills, a meront-like cell in one digestive gland, digenean trematode sporocysts in gonads, metacercariae embedded in the foot, and turbellarians in gills. The prevalence of infection was calculated for each parasite and for each sampling event, and the infection intensity was assessed for the gill coccidian, the RLO, and the hemocytic infiltration foci. The parasites with the highest prevalence were the coccidia with 73% in September. Hemocytic infiltration had a high prevalence in all sampling months, ranging from 78% to 100%.No serious damage was observed in the hosts because of the identified parasites, except for the coccidian, which disrupted part of the interlamellar bridges, and the trematode sporocysts in the gonad of the razor clams, which caused almost complete castration of the gonadal tissue. None of the identified parasites is notifiable to the World Organisation for Animal Health (OIE).

Shell growth, weight-specific growth of the soft tissue, and oxygen consumption were measured in native blue mussels, Mytilus spp., fromdifferent locations inDenmark, covering a salinity range from ∼10 to ∼30. The greatest growth rates were observed in mussels growing at average salinities of 25.7 and 29.5, the lowest rates occurred at the location exhibiting the most fluctuating salinity regime over time, with an average 20.5. Individuals in waters with a salinity of 25.7 also displayed the greatest condition index of all locations (12.1mg/cm³, P < 0.05).Mussels from five of six locations displayed similar oxygen consumption rates (P ≤ 0.83) when standardized to weight (range, 0.78–0.88 mg O₂/g/h. Of the salinities noted in the experiment, 25.7 appears to be the optimal salinity in terms of growth and condition, whereas strongly fluctuating salinity obviously involves reduced growth. At first glance, this study may appear to be just one among numerous attempts to describe the effect of salinity on growth and respiration in Mytilus edulis and its Baltic hybrids. However, themajority of studies focus on field transplants and responses to salinity alterations in the laboratory, whereas only sparse information exists on locally adapted blue mussels in relation to their ambient, native salinity.

A critical aspect of blue mussel (Mytilus edulis L.) aquaculture is industry dependence on a highly variable supply of wild seed. The objective of this study was to investigate responses of cultured pediveligers of blue mussels to different types of rope collectors. The study consisted of two trials in which competent larvae (approximately 5,000 per experimental tank—400 L) were exposed to rope collectors (polyethylene and polypropylene) exhibiting diverse structural features such as long loops, short loops, long filaments, short filaments, and smooth (Trial I—four rope types; Trial II—five rope types). In Trial I, rope segments (3 cm long) were placed at two different levels in four culture tanks (top and bottom of water column). In Trial II, segments were placed in the middle of the water column in six culture tanks. After 5 days, rope collectors were removed from experimental tanks and the number of settled larvae on each segment was counted. Rope collectors with the highest structural complexity/greatest surface area (long loops) elicited the strongest settlement response (highest densities) of mussel larvae, whereas those with the lowest complexity/least surface area (smooth) elicited the weakest response. Position within tank (top versus bottom; Trial I) had no significant effect on settlement density. Hatchery-reared mussel seed could be a reliable alternative to wild seed, and ropes with complex features should be used as larval collectors as they enhance settlement density which, in turn, could reduce production costs.

Understanding the impact of ocean acidification and warming on communities and ecosystems is a researcher priority. This can only be achieved through a combination of experimental and field approaches that would allow developing a mechanistic understanding of impacts across level of biological organizations. Surprisingly, most published studies are still focusing on single species responses with little consideration for interspecific interactions. In this study, the impacts of a 3 days exposure to three parameters (temperature, pH, and presence/absence of the predator cue of the crab Charybdis japonica) and their interactions on an ecologically important endpoint were evaluated: the byssus production of the mussel Mytilus coruscus. Tested temperatures (25°C and 30°C) were within the present range of natural variability whereas pH (8.1, 7.7, and 7.4) covered present as well as near-future natural variability. As expected, the presence of the crab cue induced an antipredator response in Mytilus coruscus (significant 10% increase in byssus secretion rate, 22% increase in frequency of shed byssus, and 30% longer byssus). Decreased pH but not temperature had a significant negative impact on the same endpoints (up to a 17% decrease in byssus secretion rate, 40% decrease in frequency of shed byssus, and 10% shorter byssus at pH 7.3 as compared with pH 8.1) with no significant interactions between the three tested parameters. In this study, it has been hypothesized that pH and predator cue have different modes of action and lead to conflicting functional responses (escape response versus stronger attachment). Functional consequences for ecosystem dynamics still need to be investigated.

The pen shell Atrina maura has economic importance in northwestern Mexico, but limitations to rear larvae in hatcheries increased the interest of scientists and producers to study aspects of reproduction and larval cultivation. Reproductive and larval performances of the species were studied in relation to the origin (depth, phases of tidal cycle) and gross condition of broodstock. The results were correlated to variations in water temperature and concentration of chlorophyll a. Tide influenced spawning response, which was between 40% and 100% successful in broodstock collected during rising and falling tides and only 10% at high or low tides (this percentage corresponds tomales only). The number and size of released and fertilized eggs and the survival of larvae were higher in pen shells collected at 5–8 m depth, compared with those collected at less than 1m. The number and size of released and fertilized eggs, number of veliger larvae, and the survival and growth rate of larvae were significantly higher in January 2012 and correspond to low temperatures, high concentrations of food, high percent of ripe gonads, high-condition index (CI), and low-muscle index (MI). These indicators were significantly lower in March 2012, when broodstock had the lowest percent of ripe gonads, the lowest CI, and the highest MI of all samples. The number and size of released eggs was positively correlated with concentration of chlorophyll a and negatively correlated with temperature, indicating that both factors play a different role in regulating reproductive output.

The fan mussel Pinna nobilis (Linnaeus, 1758) is an endangered bivalve species and is endemic to the Mediterranean Sea. Juvenile animals have been found growing on mussels Mytilus galloprovincialis (Lamarck, 1819) long line aquaculture bounces and ropes within the Maliakos Gulf (Aegean Sea). Animals were sampled from the harvested mussel lines. The results show twelve juvenile P. nobilis per ton of harvested M. galloprovincialis.

Resource managers lack an effective chemical tool to control the invasive zebra mussel Dreissena polymorpha. Zebra mussels clog water intakes for hydroelectric companies, harm unionid mussel species, and are believed to be a reservoir of avian botulism. Little is known about the digestive physiology of zebra mussels and unionid mussels. The enzymatic profile of the digestive glands of zebra mussels and native threeridge (Amblema plicata) and plain pocketbook mussels (Lampsilis cardium) are characterized using a commercial enzyme kit, api ZYM, and validated the kit with reagent-grade enzymes. A linear correlation was shown for only one of nineteen enzymes, tested between the api ZYM kit and a specific enzyme kit. Thus, the api ZYM kit should only be used to make general comparisons of enzyme presence and to observe trends in enzyme activities. Enzymatic trends were seen in the unionid mussel species, but not in zebra mussels sampled 32 days apart from the same location.Enzymatic classes, based on substrate, showed different trends, with proteolytic and phospholytic enzymes having the most change in relative enzyme activity.

Bivalve hemocyte responses are modulated by numerous biotic and abiotic environmental factors. This study investigates how nutritional stress canmodulate two hemocyte functions classically studied in bivalves, i.e., phagocytic and oxidative activities. For this purpose, we exposed zebra mussels (Dreissena polymorpha) to three nutritional conditions, for 42 days: (1) one groupwas fedwith 1×10⁶ algal cells permussel and per day, (2) a second groupwas fed with 10%of the previous food intake (1×10⁵ cells per mussel and per day), and (3) the third one was deprived of food. Hemocyte responses were assessed by flow cytometry every week for 42 days. Food deprivation was associated with a significant decrease in granulocyte size. Phagocytic activity increased in mussels exposed to the three diets, but it was more pronounced in mussels partially deprived of food (10% food intake). Mussels exposed to stressful nutritional conditions (10% and 0%) displayed significantly decreased oxidative activity from 14 days of exposure, whereas those fed on a normal diet displayed stable intracellular oxidative activity throughout the experiment. This study shows that nutritional conditions affect hemocyte morphometry and activity. Zebra mussel sensitivity to the nutritional conditions seemed low, even with total food deprivation for 42 days. It is necessary to estimate the physiological consequences of these food conditions, especially on the energetic status of this bivalve organism but also on its ability to resist to infection.

In vivo experiments were conducted with laboratory cultures of toxic Microcystis aeruginosa, to assess the potential impacts of microcystins (MC) on the immune system of the freshwater zebra mussel Dreissena polymorpha.Mussels were fed three toxic cyanobacterial strains, with different toxin profiles (presence of MC-LR and MC-LF) and one nontoxic reference strain, over a 3-wk period. Immunological analyses were carried out with mussels sampled at days 0 (baseline), 7, 14, and 21. A decrease in total hemocyte count was observed at day 14 and thereafter, in mussels exposed to the three MC-containing strains whereas no significant variation in total hemocyte count was observed in mussels exposed to the MC-free cyanobacteria. A short-term increase (at day 7 only) in the granulocyte:hyalinocyte ratio was also observed in mussels exposed to the two most toxic strains and may highlight a potential short-term inflammatory response to MC. Phagocytic rate was significantly lower in mussels exposed to cyanobacteria containing high amounts of MC. The concentration of the defense enzyme, lysozyme, was significantly higher in mussels fed with MC-containing cyanobacteria compared with the control bivalves at day 14 and subsequently increased in a timeand dose-dependent manner. In conclusion, diet exposure toMC appears to have an immunomodulatory effect on zebra mussels, manifested by an initial short-term inflammatory response and followed by the suppression of some of its immune functions. This study, therefore, highlights another potential sublethal effect ofMC on freshwater organisms and illustrates the relative toxicities of the different MC variants, MC-LF being potentially more toxic than MC-LR.

The muricid mollusc Dicathais orbita produces Tyrian purple, which is a brominated derivative of the blue dye indigo. This study aimed to establish whether distinct bacterial communities occur in the organs of D. orbita associated with Tyrian purple production and to identify indole-producing bacteria using 16S rRNA sequencing. Biochemical profiles of microbial communities from different D. orbita tissues were investigated and the composition of aerobic heterotrophic bacterial populations from homogenates and swabs assessed. There were significant differences in biochemical activity profiles and bacterial communities cultured from different D. orbita tissues, but no significant differences between males and females. Bacterial communities derived from foot tissue and seawater samples were similar. The biochemical and molecular evidence from swabs and tissue homogenates suggest indole-producing isolates are Vibrio spp. This study suggests Tyrian purple indole precursors could be obtained from opportunistic ubiquitous bacteria.

Abalone are enigmatic, displaying subtle responses to stress, including a delayed onset of morbidity, and death after severe stress. The present study therefore sought to further elucidate the nature of stress responses in the blackfoot abalone Haliotis iris and develop practical indices to quantify stress and forecast survival. Abalone were challenged with air exposure (16°C, 4–120 h). Physiological responses were assessed at three organizational levels: whole organism (heart rate), extracellular (hemolymph metal concentrations), and intracellular (hemocyte lysosome stability). Hemolymph sodium:potassium ratio showed a strong negative correlation with emersion time (R² = 0.82) and a reasonable capacity to predict subsequent survival (R² = 0.50); a [Na]:[K] of 23 was representative of an undisturbed abalone, whereas values less than 15 typically indicated morbidity. Hemocytes tended to lyse before lysosome destabilization could be quantified by neutral red loss; the stability assay therefore failed to yield meaningful data. Resting heart rate declined from 19.4 min^-1 (undisturbed) to a minimum of 1 min^-1 recorded after 48 h emersion; however, the correlation between heart rate and emersion time or subsequent survival was weak. Hemolymph sodium:potassium ratio warrants further investigation as a practical and sensitive forensic tool to quantify stress, but will require complementary approaches to robustly determine the survival tipping point.

The Correct cuttlefish Sepia pharaonis (Ehrenberg, 1831) is an abundant cephalopod in Persian Gulf and Oman Sea. Despite the commercial and conservation importance of this species, information on population structure and diversity at the molecular level in S. pharaonis is scarce. Seventeen microsatellite loci from other species were analyzed to study genetic variation in populations of S. pharaonis from Iranian waters of the northern Persian Gulf coasts (Bandarabass, Lengeh and Bushehr). Eleven of the seventeen primer pairs failed to amplify, whereas six primer pairs successfully amplified: four pairs were polymorphic and two pairs were monomorphic. All loci were significantly deviated from Hardy—Weinberg equilibrium (P < 0.01). In the three samples of Persian Gulf analyzed, the four polymorphic microsatellite loci exhibited a mean allele number (N_a) of 7.5, mean expected heterozygosity (H_e) of 0.802 and mean observed heterozygosity (H_o) of 0.541.Weak genetic differentiation was present among the populations with F_ST values ranging from 0.020 to 0.31. This investigation represents the first microsatellite study of population genetics of this species in Iran, and the reported results could be of interest for management and conservation programmers of this species.

The aim of this study was to test the effect of copper supplementation in a formulated feed on the growth, feed efficiency, and nutritional composition of subadults Octopus vulgaris, with particular reference to the differences in the content of copper in the tissues (muscle, digestive gland, and hemolymph). Two formulated feeds were supplied to subadults octopuses kept individually for 56 days: Basal diet [11.6 mgCu/kg dry weight (dw)], and another feed with a similar composition but including a copper supplementation (copper diet: 115.2 mgCu/kg dw). No significant differences (P > 0.05) were detected in the respective growth rates (0.88% body weight/day), FE (79.5%–82.1%), proximate composition, hemolymph hemocyanin (1.6–1.8 mmol/L), hemolymph copper (0.19–0.20 mgCu/mL), or muscle copper levels (22.7–23.2 mgCu/kg dw). No significant changes were detected on proximate composition, hemocyanin and hemolymph, and muscle copper levels between animals fed formulated feeds and an initial group fed natural diet based on crab and fish (P > 0.05). The only parameter which showed a significant difference (P < 0.05) was the copper level in the digestive gland: 1,797, 390, and 1,148 mgCu/kg dw for initial (natural diet), basal and copper diet, respectively (P < 0.05). Considering the experimental conditions of this study, copper supplementation is not effective in improving the performance of a formulated feed for octopus.

The red octopus Octopus maya is an endemic species of the continental shelf of the Yucatan Peninsula, Mexico and supports the largest octopus fishery in the American continent. Little is, however, known about its spatial dynamics. The study of the space-time variation of catchability is a key element in the stock assessment, because it allows behavioral aspects of the resource and qualities of the various exploitation strategies to be clarified, which are essential for the fishery management. The objective was to analyze the spatio-temporal variations of the abundance and catchability of the octopus O. maya on the continental shelf of the Yucatan Peninsula, Mexico. During the fishing season of 2012 (August–December), fishery landings from the small-scale fleet in 13 ports of the Yucatan Peninsula, were analyzed to obtain data on catch, effort and fishing zone for O. maya. During the closed season of 2013 (January–July) fishing hauls were performed across a network of stations along the coast of the Yucatan Peninsula. Spatio-temporal variations in mean catch per unit effort (CPUE) in terms of number of organisms per hour of effective fishing were analyzed. Catchability and its variation with size, time, and zone were estimated through a model based on the Leslie transition matrix and frequency distributions of mantle length. The results showed significant changes in the distribution of O. maya. During the fishing season, the greatest abundances were found along the coast of Campeche (western zone), whereas, during the closed season the highest abundances were recorded along the coast of Yucatan (eastern zone). Trends of decreasing and increasing catchability were observed with respect to size according to the different zones. A high catchability was presented for small sizes along the coast of Campeche during the fishing season. The results indicate the need to investigate possible management measures differentiated by region (west-east) to ensure the fishery sustainability.

Incorporating fecundity into stock assessment models may improve stock assessment and management of Bristol Bay red king crab Paralithodes camtschaticus. To do this, the size—fecundity relationship for the population must be established, including variability due to female reproductive state. In 2012, egg clutches were collected from red king crab in Bristol Bay, AK, and individual fecundity was estimated. Best evidence suggests small females were primiparous (brooding first egg clutch), which provided the opportunity to compare estimated fecundity of primiparous and multiparous (brooding second or subsequent egg clutch) females. In the best-fit model, fecundity increased with female size and below 108.8 mm carapace length (CL) the slope of the size—fecundity relationship decreased by 27%.Multiparous females were 28%–30% more fecund than primiparous females of the same size. If managers incorporate fecundity into stock assessment models, the differences in fecundity between primiparous and multiparous females should be considered, otherwise population fecundity will be overestimated if the size—fecundity relationship of only multiparous females is used in the calculations because of the differences in fecundity between primiparous and multiparous females of the same size.

To better understand the factors influencing larval dispersal and settlement of the snow crab Chionoecetes opilio in its natural habitats, we tested the effects of salinities ranging from 18 to 38 and 20–38 on the survival and developmental duration of snow crab larvae in the zoeal and megalopal stages, respectively. Survivals to second-stage zoeae and to megalopae were highest at salinities of 20–38 and 26–38, respectively. There were no significant differences in survival among megalopae reared at salinities between 24 and 38, although survival tended to be higher at salinities range 28–36. The mean periods from hatching to the second zoeal and megalopal stages, and from the megalopal to first crab stage, were shortest at salinities of 30, 30, and 32, respectively, and progressively increased at salinities above and below these values.

Understanding how growth rates are influenced by environmental conditions is important for proper management of commercially harvested species, especially under current and predicted future conditions of global climate change. Blue crabs are of high commercial value in the United States, but are declining in number throughout their range. Previous laboratory and field studies suggest that temperature and salinity play a role in blue crab growth rates, although the results of these studies have been inconclusive and, in some cases, contradictory. Furthermore, these studies have focused primarily on later juvenile stages [>20 mm carapace width (CW)]. This study examined the effects of temperature and salinity on early juvenile (∼2.5–16 mm CW) blue crab Callinectes sapidus growth rates. Crabs were reared in the laboratory under six different temperature and salinity treatments from the megalopal stage until the sixth juvenile instar. Compared with crabs reared at lower temperature, crabs reared at higher temperature exhibited a decreased intermolt period (IMP) and also decreased growth per molt. Salinity had no significant effects on IMP or growth per molt at 20°C and only slight effects on IMP at 30°C. These results suggest that temperature plays a major role in determining blue crab growth rates during the early juvenile instars, but the effects of salinity are relatively minor. Given forecasted increases in temperature throughout the geographic range of the species, these results suggest that blue crabs will reach maturity faster in the future, but will be smaller in size. Future studies should investigate potential causes of the correlation between salinity and blue crab size, and consider additional environmental influences.

A significant pathogen of crustaceans is thought to be Hematodinium. Much is known about the ecology and the effects of this disease on the sustainability of crustacean populations, but significantly less is known about the mode of transmission and fate of infected animals. Attempts have been made to transmit the disease under aquarium conditions to several species of crabs. These studies have shown a great deal of variation in the resulting levels of mortality and the timescale of disease progression. To determine if Hematodinium infections are the significant drivers of mortality in juvenile edible crabs (Cancer pagurus), crabs were injected with either 1 × 10⁵ trophonts from an infected animal or sterile saline. Crabs were bled every 4 wk to determine the progression of infection and its effect on the total number of circulatory hemocytes. Thirty-three percent of the Hematodinium-injected crabs became infected and mortality occurred between 93 and 378 days postchallenge. Infected crabs appeared to molt less frequently than their uninfected counterparts. Both Hematodinium-infected and uninfected crabs exhibited infections by a number of other disease-causing agents including mikrocytid parasites, the fungus, Ophiocordyceps, and unidentified bacteria. These latter agents appear to be the key drivers of the mortality observed in both the Hematodinium infected and uninfected crabs.

Crustaceans often undergo periods of starvation, due to natural food shortage or physiological constraints. During these periods, several metabolic and behavioral changes can occur. This study evaluates how the brown shrimp Crangon crangon (Linnaeus, 1758) responds to prolonged deprivation of food in two seasons of the year, and how this species mobilizes its energetic reserves. Shrimps caught in June (summer) and October (autumn) 2010 in the Minho estuary (north of Portugal) were placed in individual cages in experimental aquaria and kept in starvation until the last shrimp died or was sacrificed (six shrimp per aquarium every week). The energetic content, total lipids and total protein, and the oxygen consumption rate were compared between seasons, sacrificed and naturally dead shrimp, and considering the weeks of starvation. Summer shrimp proved to be better prepared to endure starvation than those caught in autumn: they survived 2.5 times longer, had a higher Fulton condition factor, higher energy, and higher lipid and protein content at the beginning of the experiments. The percentage of total body protein decreased significantly in the first week, stabilized in the following to decrease again abruptly in the fifth week. The percentage of total lipids only started to decrease after four weeks. This suggests that (1) C. crangon probably uses protein as a first energetic resource, followed by carbohydrates and eventually lipids, though to a much lesser extent; and (2) after 4 wk of starvation, a critical point is reached when structural components may be mobilized to satisfy maintenance costs.

A Habitat Suitability Index (HSI) model was developed using four environmental variables (bottom temperature, bottom salinity, depth, and bottom substrate type) and 29 years of spring and fall lobster surveys for evaluating the spatiotemporal variability of suitable lobster habitat in Long Island Sound (LIS). The suitability indices calculated for the four environmental variables were combined to form a composite HSI using an arithmetic mean model and geometric mean model. A cross-validation study was conducted to evaluate the predictive performance of the HSI models. Annual geographic information system maps of estimated HSI values were produced using Kriging interpolation for adult and juveniles in spring and fall from 1978 to 2012. The overall spatial distribution of suitable habitat for lobster was mainly concentrated in the western-central part of LIS during spring (April–June), but showed clustering patterns throughout LIS during fall (September–October). An examination of the temporal change in annual median HSI values identified possible time blocks when habitat conditions were extremely poor and revealed a statistically significant decreasing trend in availability of suitable habitat for juveniles during spring from 1978 to 2012. Spatiotemporal variability in availability of suitable habitat may imply changes in carrying capacity of LIS for the American lobster.

The behavior of stage IV American lobster (Homarus americanus) larvae in relation to various water temperatures was observed in laboratory. Time budgets were documented in 2009 in trials using a single larva per experimental enclosure in relation to three temperature exposures (10°C. 15°C. and 20°C). Larvae acclimated at a given temperature (15°C and 20°C) were used. The same treatments were used in 2010, where one larva was observed within a group of five individuals per experimental enclosure. Larvae took less time to hide when they were acclimated to 15°C and then exposed to 20°C. Video observations showed that larvae were stressed (repeated tail flicks) when treatments simulated important heat shocks (e.g., larvae acclimated at 20°C and exposed to 10°C). Results for single larva were similar to those from groups of larvae. The tail-flicks display was also observed in 2010 with larvae acclimated at 15°C and then exposed to 10°C. Observations from both years showed that the time budget was similar regardless of the larval cohort used in trials (different brood stocks and times of the season). Overall, results confirm that water temperature affects the behavior of lobster larvae. Acclimation to a given temperature, however, tends to show that larvae may acclimate to cold water. This study provides interesting results to better understand the ecology of American lobster, particularly at the time of settlement. These results should also be of interest for the lobster industry, which looks to improve stock enhancement procedures through, for instance, lobster-stocking programs.

During the past 40 y, natural stocks of the edible sea urchin Paracentrotus lividus have declined sharply in many sites along the French Mediterranean coast. Despite current management measures, this resource remains at low densities, raising concerns among commercial fishermen and managers. The reseeding of depleted sea urchin populations is currently under consideration. In this study, a pilot-scale experiment was conducted to assess the feasibility of such an operation and to evaluate the impact on both the population structure and genetic diversity of wild communities. The genetic diversity and population differentiation of wild populations was assessed before reseeding five depleted populations with 250,000 hatchery-produced juveniles. A year after release, parentage assignment tests were performed on small recaptured sea urchins to address their origin. Sea urchins from the hatchery were found at two of five sites, representing 3% and 12% of the total recaptured urchins in the concerned sites. The genetic analysis performed with six microsatellite loci revealed genetically homogeneous populations in the area studied. Within and among populations, genetic diversity seems not to be affected by introducing juveniles from the hatchery into wild populations. Therefore, following strict recommendations, reseeding could be considered a potential and efficient management tool to restock or sustain overexploited populations in areas where natural recruitment appears insufficient.

In the mid-2000s the U.S. west coast oyster industry experienced several years of significant production failures. This industry has been referred to as the “canary in a coal mine” for ocean acidification (OA). Industry-led collaboration with university and government scientists identified a relationship between elevated carbon dioxide in seawater and poor oyster seed production. This multiyear production slow-down resulted in significant economic losses to the industry and spurred state and regionally led initiatives to examine the current and potential future impacts of OA. To examine the perceptions and understanding of OA by the U.S. west coast shellfish industry, a regional survey of the industry was conducted, covering oyster, mussel, clam, geoduck, and abalone producers. The web-based survey addressed four general areas: experience, understanding, concern, and adaptability. There were 86 total respondents from industry, resulting in a response rate of 46% with 96% of respondents answering all 44 questions. Seventy percent of respondents were owners or managers of a shellfish business. Findings from the survey indicate that approximately half of the industry had personally experienced a negative impact from OA. This personal experience generally led to a higher level of concern about OA; however, self-reported level of understanding of OA resulted in slightly less concordance with the level of concern. Greater than 80% of the shellfish industry noted that OA will have consequences today, approximately four times higher than the U.S. public's perception of the threat. Finally, greater than 50% of the industry felt that they would be able to somewhat or definitely adapt to OA.

Ecosystem services provided by dense populations of filter-feeding bivalves include the potential for sequestration of nutrients acquired by feeding on phytoplankton whose growth is stimulated by urban and suburban nutrient input. Using transplanted oysters, Crassostrea virginica, the potential of using an aquaculture approach to grow, harvest, and therefore remove nitrogen from coastal bays with high nutrient input was studied. Jamaica Bay—urban high nitrogen input (input ∼5.8 × 10^s kgN/y)—was contrasted with Great South Bay—suburban and medium nitrogen input (input ∼8.5 × 10⁵ kgN/y)—both located on the south shore of western Long Island, NY. A growth period of June–October was used with a harvest in October as the basis for an estimate, and nitrogen in soft tissues and shell was measured in October, minus the starting values, because both tissue and shell would be removed at the time of harvest. Nitrogen sequestration potential was determined from growth in aquaculture cages, extrapolated to 50% cage coverage over a range of areas in each bay. In the extreme case of total suitable habitat coverage, oysters in Jamaica Bay could extract a total of ∼61% of nitrogen input, and 47% if 5,000 acres were covered; whereas impressive, the oysters could not be sold for food and the cost of such a plan would be prohibitive. In Great South Bay, aquaculture covering 5,000 acres would take up 148% of the nitrogen input, which is encouraging because aquaculture leases are beginning to be awarded in this bay and most waters are clean enough for harvest and human consumption. The results suggest that an aquaculture-based oyster fishery might compensate for the nonpoint source nitrogen input that is common in many estuaries where nitrogen input is moderate and sewer systems are not present.