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A multistep invasive species methodology was used to evaluate the probability that the deployment of sterile non-native oysters (Crassostrea ariakensis,called Asian oyster) in field-based aquaculture could give rise to a reproductive population in Chesapeake Bay. Several pathways that could potentially lead to the unintentional release of reproductiveC. ariakensisfrom aquaculture were identified. For the four quantifiable pathways, a probability was estimated for each step based on knowledge of ecological rates. A conservative estimate for the number of reproductiveC. ariakensisthat could arise over one spawning season at a hypothetical aquaculture site was estimated. A statistical expansion of this probability estimated that it is highly likely that the cultivation of putatively sterileC. ariakensiswould initiate a reproductive population in Chesapeake Bay over a 10-year time span. The potential benefits of restoration actions involving non-native species in estuarine ecosystems must be weighed against potential ecological risks. A probabilistic approach can provide a useful method for summarizing the risk of an unintended introduction that may occur despite a reasonable and presumably “safe” approach for realizing benefits of a non-native species in aquaculture. The results presented here have important implications for future proposals involving the commercial use of non-native species in natural ecosystems. [ABSTRACT FROM AUTHOR]

The costs and benefits of non-native introductions as a restoration tool should be estimated prior to any action to prevent both undesirable consequences and waste of restoration resources. The suggested introduction of non-native oyster species, Crassostrea ariakensis, into Chesapeake Bay, USA, provides a good example in which the survival of non-native oysters may differ from that of native oysters, Crassostrea virginica, during the larval stage. Experiments were conducted to compare the predation vulnerability of native and non-native oyster larvae to different predator types (visual vs. non-visual, benthic vs. pelagic). The results suggest that the non-native larvae are more vulnerable to visual and non-visual pelagic predators. Although vulnerability was similar for larvae exposed to benthic non-visual predators, the consumption of one non-native strain was higher than the consumption of native C. virginica larvae. When vulnerability data are combined with predator feeding rates, the predation mortality for non-native larvae in the wild can be much higher than for native larvae. Small changes in larval mortality rates can yield large changes in total larval delivery to the reef for settlement, so these differences among species may contribute to differences in settlement success. These results provide an example of how a comprehensive examination of the perceived benefits of non-native introductions into complex ecosystems can provide important information to inform management decisions. [ABSTRACT FROM AUTHOR]

Introducing non-native species can create serious environmental risks, such as changing the attributes of ecosystem, displacing the native species, clogging the natural waterways and channels. Careful examination of the possible consequences before implementation can prevent the adverse consequences of invasive species. However, policy analysis for such an action is often difficult, due to the complexity of the marine environment, and the interactions among the species therein. This paper presents a spatial-explicit agent-based simulation model for analyzing the environmental risks of introducing non-native species, Suminoe oyster ( Crassostrea ariakensis). It is considered to be introduced into the Chesapeake Bay, USA, where there is a native Oyster species (Eastern oyster, Crassostrea virginica) with declining population. The simulation result indicates that the non-native species will likely displace the native species, but this can be controlled by setting up a different harvest plan, and the location and the number of initial spat introduced. [ABSTRACT FROM AUTHOR]

Crassostrea ariakensis is an important aquacultured oyster species in Asia, its native region. During the past decade, consideration was given to introducing C. ariakensis into Chesapeake Bay, in the United States, to help revive the declining native oyster industry and bolster the local ecosystem. Little is known about the ecology and biology of this species in Asia due to confusion with nomenclature and difficulty in accurately identifying the species of wild populations in their natural environment. Even less research has been done on the population genetics of native populations of C. ariakensis in Asia. We examined the magnitude and pattern of genetic differentiation among 10 wild populations of C. ariakensis from its confirmed distribution range using eight polymorphic microsatellite markers. Results showed a small but significant global θST (0.018), indicating genetic heterogeneity among populations. Eight genetically distinct populations were further distinguished based on population pairwise θST comparisons, including one in Japan, four in China, and three populations along the coast of South Korea. A significant positive association was detected between genetic and geographic distances among populations, suggesting a genetic pattern of isolation by distance. This research represents a novel observation on wild genetic population structuring in a coastal bivalve species along the coast of the northwest Pacific. [ABSTRACT FROM AUTHOR]

Abstract: The Suminoe oyster Crassostrea ariakensis has been attempted to be introduced in the Chesapeake Bay, USA, as an alternative to the eastern oyster Crassostrea virginica. Commercial production of Suminoe oysters is currently restricted due to the incomplete understanding of their biological, physiological and immunological nature. Accordingly, understanding immune system of C. ariakensis is crucial to prevent disease associated mortality and subsequent management of the Suminoe oyster. We investigated immunological activities and morphology of hemocytes of the Suminoe oyster using flow cytometry and light microscopy. Three types of hemocytes were identified in the hemolymph including hyalinocyte, granulocyte and blast-like cells. Hyalinocytes were the largest cells and the most abundant, while granulocytes were intermediate-size cell containing numerous granules in the cytoplasm. Blast-like cells were the smallest and least numerous. Flow cytometry revealed that the granulocytes are most active in the cell phagocytosis and spontaneous reactive oxygen species (ROS) production. The hyalinocytes also showed a certain level of the phagocytosis and oxidative activity but in a lesser extent than the granulocytes. In contrast, the blast-like cells did not show any phagocytosis or oxidative activity. The flow cytometry used in this study confirmed that as observed from other marine bivalves, the granulocytes are the main hemocytes involved in the cellular defence in the Suminoe oyster. [Copyright &y& Elsevier]