In the Pacific Northwest the environment has changed in a manner that has contributed to increase mortality of bivalve larvae in hatcheries and also appears to have decreased natural recruitment. Several factors have been attributed to this problem including temperature, ocean acidification, and re-emerging pathogens. We are testing the impact of single and multiple biotic and abiotic stressors (i.e. decreased pH) on larval bivalves with a focus the Pacific oyster. In addition, population level effects of ocean acidification will be determined using select SNP markers.
Shellfish are important species for our growing marine shellfish aquaculture industry and play critical roles in our marine ecosystems, an environment that is increasingly threatened by environmental change. In the Pacific Northwest the environment has changed in a manner that has contributed to increase mortality of bivalve larvae in hatcheries and also appears to have decreased natural recruitment. Several local shellfish hatcheries, upon which nearly the entire bivalve culture industry relies, have experienced severe losses (e.g. up to 59%) over the past two years. Several factors have been attributed to this problem including temperature, ocean acidification, and re-emerging pathogens. Given the large-scale environmental change observed in our marine ecosystems and the relationship of host stress response and pathogen virulence with environmental conditions, it is critical to examine the problems facing bivalve larvae from a regional perspective by systematically assessing how the environment influences the spread of disease and the ability of oysters to effectively respond to stress. The goal of this proposal is to characterize the factors that threaten the aquaculture industry and wild shellfish. The primary approaches include a series of laboratory experiments and environmental sampling. For the current proposal has been developed to test the following hypothesis: Environmental stressors (elevated temperature and reduced pH) will enhance disease expression and reduce larval bivalve survival. More specifically we will test the impact of single and multiple biotic and abiotic stressors on larval bivalves with a focus on the most economically important regional species, the Pacific oyster (Crassostrea gigas). In order to assess the impact of biotic and abiotic environmental factors on bivalve health, we will also assess the abundance of oysters and other larvae in Willapa, Dabob, and Netarts Bays in relation to water quality parameters (pH, temperature, dissolved oxygen, salinity, alkalinity, chlorophyll A, and pathogen load). The specific research objectives are to: 1) Characterize the interrelationship of altered environmental conditions, pathogen, and oyster response under controlled conditions and 2) Identify factors in Pacific Northwest hatcheries and in the wild that are associated with poor oyster larvae survival. Upon completion of this research we will have a better understanding of how environmental change will impact our marine ecosystem. This information will allow us to better predict mortality events, improve hatchery practices, manage wild populations, and develop improved broodstock. Furthermore, marine bivalves are an excellent sentinel species for environmental perturbation and the novel bio-monitoring procedures developed in this project could easily be transferred to other species and systems.
Funding for this research is provided by