Christiane Biermann, Friday Harbor Laboratories, University of Washington
$49,050

Genetic population structure of Northwest Straits green sea urchins (Strongylocentrotus droebachiensis): The impacts of harvesting and marine protected areas

The goal of this project is to provide scientific information that can guide marine conservation efforts in the Northwest Straits/Puget Sound region in coastal Washington. We plan to analyze the population structure of an ecologically and commercially important invertebrate species, the green sea urchin (Strongylocentrotus droebachiensis). We will investigate both its abundance and the genetic relatedness between different population patches. This species will serve as an easily accessible model for the diverse biota in this region. Marine Protected Areas (MPAs) are the principal management tool in the conservation of marine species and habitats. The criteria for the selection of protected areas include the capability to support healthy populations and to supply larvae (propagules) to other sites, both inside and outside reserves. To select the most effective network of protected areas, we need to understand the paths of migration or dispersal of organisms. Most marine species have at least one free-swimming or drifting stage in their life history that is subject to being moved around by currents. The microscopic larvae of sea urchins are not very strong swimmers; hence their dispersal reflects physical oceanographic processes. Once they arrive in a suitable habitat, they can survive for decades. The genetic affiliation of a population therefore represents migration integrated over a long time period. It will be interesting to compare this average migration to the results of the local drift card studies, which illustrate dispersal at one point in time. We can then use the migratory (drift) path of sea urchins as a representative model for managing other rare or valuable species and the resources on which they depend. The number of green sea urchins will be surveyed inside and outside of Marine Protected Areas and fished regions (in cooperation with scientists at the Washington Department of Fish and Wildlife) by filming underwater shorelines with Friday Harbor Labs' new Remotely-Operated Vehicle. This part of the project will involve participation of K-12 students. In selected plots, sea urchins of two different size classes will be collected by SCUBA diving. Small tissue samples (tubefeet) will be taken and analyzed by genetic fingerprinting at Friday Harbor Laboratories. The identification of rapidly evolving "microsatellite" genetic markers that vary at small geographic scales is a complex procedure that has already been completed for this species both by the Principal Investigator, Dr. Biermann, and by the collaborator, Dr. Cohen. The cooperative environments at Friday Harbor Labs and the UW's School of Fisheries are ideal for the analyses and dissemination/application of the data. We trust that the results will help us understand the dynamics of local marine populations, and to manage our natural resources wisely.