Assessing the contribution of aquaculture and restoration to wild oyster populations in a Rhode Island Coastal Lagoon

Authors: JARIS, HANNAH - American Museum Of Natural History; BROWN, D - Nature Conservancy; Proestou, Dina

Submitted to: Conservation Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/31/2019
Publication Date: 2/22/2019
Citation: Jaris, H., Brown, D.S., Proestou, D.A. 2019. Assessing the contribution of aquaculture and restoration to wild oyster populations in a Rhode Island Coastal Lagoon. Conservation Genetics. 20(3):503-516. https://doi.org/10.1007/s10592-019-01153-9.
DOI: https://doi.org/10.1007/s10592-019-01153-9

Interpretive Summary: The decline of the eastern oyster (Crassostrea virginica) has prompted various restoration and aquaculture efforts. Recent field surveys in Rhode Island suggest that wild populations are increasing, yet the factors contributing to expansion are unknown. We used a population genetic approach to characterize genetic differences between wild and cultured oyster populations and explore the extent of connectivity and admixture between groups. Individual oysters from four wild, three farmed, and two restored populations were collected within or just outside Ninigret Pond, a coastal lagoon highly influenced by human activity, and genotyped at 13 microsatellite loci. Results from the multilocus genotype data showed that wild populations were more genetically diverse than the cultured populations. We also observed significant genetic differentiation between paired wild and cultured populations but not between pairs of wild populations. A cluster analysis detected substantial admixture between wild and cultured groups. As aquaculture and restoration activities are forecasted to increase in the future, analyses similar to the ones reported here should provide insight into how specific human activities can shape patterns of genetic diversity in free standing wild oyster populations and inform and improve restoration and aquaculture efforts.

Technical Abstract: To offset wild eastern oyster population declines, the aquaculture industry has been steadily increasing since the 1970’s and well-intentioned restoration efforts using hatchery-reared strains have been and continue to be initiated in Rhode Island (Rice et al. 2000). We applied population genetic methods to quantify genetic diversity and the degree of genetic differentiation among remnant wild and cultured populations in order to better understand the role anthropogenic manipulations play in the health and sustainability of wild eastern oyster populations living in Ninigret Pond, the largest multi-use coastal lagoon in southern Rhode Island. Our results indicate higher levels of genetic diversity within the wild populations compared to the cultured stocks and significant levels of differentiation between the wild and cultured populations. Cluster analysis further suggests that the less genetically diverse cultured populations are recruiting to wild populations and wild populations in close proximity to restoration efforts may be more heavily impacted. As aquaculture and restoration activities are forecasted to increase both inside and outside the banks of Ninigret Pond in the future, it will be important to monitor levels of genetic diversity within and differentiation among wild and cultured populations moving forward. Such information will no doubt elucidate how freestanding wild populations respond to nearby aquaculture and restoration activities and should improve efforts to manage and protect our natural resources.