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Estuaries provide valuable habitat for the eastern oyster (Crassostrea virginica). Although salinity at a given location fluctuates regularly with tides, upbay and downbay salinity differences span a broad estuarine salinity gradient. Higher salinity habitats downbay support faster oyster growth, whereas lower salinities upbay act as a refuge from predation and disease but slows growth. Two experiments were performed to investigate the effect of salinity, postsettlement salinity changes, and shell morphology on juvenile oyster growth. One experiment used wild oyster spat collected from three distinct Delaware Bay salinity zones that were then transplanted into various salinity conditions in the laboratory, where growth was monitored. Transplanting into low salinity led to decreased growth compared with transplanting to higher salinity, and growth of oyster spat was overall highest for spat from the lowest salinity source. Growth did not differ among shell morphologies. A second experiment used hatchery reared larvae set in one of four different salinity conditions. Those spat were maintained in settlement salinities 22, 16, 10, and 6 for 2-3 wk postsettlement, then measured before fully factorial transfer into new salinity conditions with measurement 3 wk later. Lower final salinity treatments were associated with lower growth, lower initial salinity treatments were associated with faster final treatment growth, and final growth depended on the interaction between initial and final salinity. Therefore, in addition to the effects of acute salinity changes on growth, early postsettlement hyposalinity stress can generate compensatory juvenile oyster growth. As increased freshwater events due to climate change are expected in the Delaware Bay and regionally in the Northeast, these results indicate that nonlinear early life stress responses are important to quantify to better understand oyster stock resilience and plan management. KEY WORDS: Oyster, spat morphology, salinity, growth, carryover effects, INTRODUCTION Oysters (Crassostrea virginica Gmelin, 1791) provide many economic benefits and ecosystem services to the east coast of the Americas. They are euryhaline and can sustain populations in salinities ranging [...]

The eastern oyster Crassostrea virginica contributes important ecological and structural elements to estuarine ecosystems worldwide. Oyster reef persistence requires regular recruitment as well as growth by existing individuals. Saltmarsh tidal creek oyster population age structure and growth rales directly influence local benthic-pelagic coupling and biogenic habitat formation. Recruitment monitoring, substrate deployments (2017-2020), and field surveys (2018) were conducted in North Inlet Estuary, SC, to quantitatively describe oyster age-shell height relationships, population age structure, daily growth rates, and survivorship. Multiple recruitment events resulted in three to four cohorts each year. Oysters exhibited rapid shell growth but most died by the end of their second growth season after attaining shell heights of less than 100 mm. Daily growth rates immediately after recruitment (approximately 0.07-0.29 mm [day.sup.-1]) and within the first 2 y (0.1-0.4 mm [day.sup.-1]) allow maximum shell heights of 50-55 mm after to 6-8 mo, 80 mm within 1 y, and 140 mm within 1.6 y. Recruitment timing strongly influenced shell heights after 1 y. with July recruits approximately 33% larger than May recruits within the same year. The North Inlet oyster population age structure was dominated by oysters in their first (55%) or second (45%) growth season, with individuals less than 100 mm shell height composing approximately 99% of the population. Oyster survivorship beyond 2 y appears to be unusual. The opportunistic life history strategy used by North Inlet oysters incorporates multiple large recruitment events each year and rapid growth rates to offset short life spans so as to maintain reef populations and related ecosystem services. KEY WORDS: oyster, Crassostrea virginica, recruitment, life history strategy, life expectancy, population dynamics, saltmarsh tidal creek, INTRODUCTION Eastern oysters (Crassostrea virginica) contribute fundamental ecosystem services to estuarine and coastal habitats worldwide (Ulanowicz & Tuttle 1992, Coen & Luckenbach 2000, Gutierrez et al. 2003, Coen et al. [...]

ABSTRACT Production of larger, rounder, high-quality cultured pearls with fewer circles is one of the main challenges of Pinctada margaritifera aquaculture faced by every pearl farm in French Polynesia. Although [...]

ABSTRACT 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; [...]

ABSTRACT Sustainability of a fishery is traditionally and typically considered achieved if the exploited population does not decline in numbers or biomass over time as a result of fishing relative [...]

Juvenile oysters (Crassostrea gigas) (produced in November 2009) reared under uniform hatchery conditions for 4 months were selected for extreme growth rate differences by repeatedly taking larger and smaller individuals to achieve weight differences >30 x between fast (F) and slow (S) growers. The physiological basis of differential growth was analyzed in experiments in June 2010, where components of energy gain (clearance and ingestion rates and absorption efficiency), energy loss (metabolic rates) and resulting scope for growth (J [h.sup.-1]) were compared for groups of F and S oysters fed three different ration levels (≍ 0.5, 1.5 and 3.0 mg of total particulate matter [L.sup.-1]). In both F and S oysters, a higher food ration promoted asymptotic increases in energy gain rates through regulatory adjustments to clearance rates, which maintained similar absorption efficiencies across the food concentrations. No significant differences were found between growth groups in mass-specific physiological rates (i.e., per unit of body mass). However, the scaling of these rates to a common size in both groups using allometric coefficients derived for C. gigas revealed higher energy gain rates coupled with lower metabolic costs of growth in fast growers. Thus, appropriate size-standardization is essential in accounting for observed differences in growth rate. Present results are in accordance with previous reports on other bivalve species on the physiological processes underlying endogenous growth differences, suggesting that the same interpretation can be applied to the extremes of these differences., Introduction Growth rates vary among individuals in natural bivalve populations (Mallet and Haley 1983; Dickie et al. 1984; Brown 1988) even when exposed to similar environmental conditions. This indicates the [...]

ABSTRACT Juvenile winged pearl oysters, Pteria penguin, were cultured for 6 mo in three commonly used culture units (panel nets, plastic mesh trays, and pyramidal pearl nets) at two dissimilar [...]

ABSTRACT Pteria penguin is an important commercial bivalve species that is used in the production of half pearls known as mabe. Expansion of this industry in places with low natural [...]

ABSTRACT Crassostrea gigas was introduced in Anegada Bay (North Patagonia, Argentina), in 1981 for aquaculture purposes. The species has, since established in the field, covered all available hard substrata in [...]

Infection by Bonamia ostreae has caused extensive mortalities of oysters Ostrea edulis through European and United States coasts for at least 25 years. The development of a bonamiosis-resistant strain seems a promising strategy to fight against the disease. As a first step, evaluation of variability in productive traits and disease susceptibility of European populations was performed to identify favourable oyster populations with which to start selective breeding in Galicia (NW Spain). Oysters taken from Greece, Ireland, Ortigueira (Galicia) and Coroso (Galicia) were used as brood stock, and 19 seed families were produced (4-5 families from each origin). The oyster families were used to assess variability through on-growing in an area of the Rja de Arousa heavily affected by bonamiosis. Results showed significant differences in growth, mortality and susceptibility to bonamiosis and other diseases, both between origins and between families under origins. Bonamiosis was associated with mortality in the late stage of oyster on-growing. Indications of natural selection of bonamiosis less-susceptible oysters due to the long exposure of the Ortigueira population to bonamiosis were found. Other symbionts and pathological conditions were detected, of which herpes-like viral infections and disseminated neoplasia could also cause mortality. An index of the overall incidence of pathological conditions (OIPC) was estimated for each family. A significant correlation between the OIPC and the cumulative mortality of the families was noted. On average, oysters from autochthonous origins showed better performance. The results obtained with the best-performing families suggest that the profitability of oyster farming in Galicia would improve, even under bonamiosis pressure, by using appropriate oyster spat.

For members of the West Coast Shellfish industry, their world is the oyster. Every year the industry harvests and sells millions of dollars worth of oysters, clams, and mussels, and [...]