Joanne Linnenbrink

Joanne Linnenbrink

Former Graduate Student

M.S, Biology

Genetic population structure of the Olympia oyster, Ostrea lurida, in southern California

My master’s thesis is co-advised by Dr. Zacherl and Dr. Doug Eernisse, with Dr. Ryan Walter and Dr. Jennifer Burnaford serving on my thesis committee. It is focused on examining the population genetic structure of the Olympia oyster (Ostrea lurida) in southern California. Historical oyster beds on the west coast of the United States have been subjected to overharvesting, human disturbances such as dredging, construction of man-made structures and, in northern regions, introduced predators. Today, 85% of worldwide oyster beds and reefs have been lost and, in southern California, less than 1% of the oyster’s original habitat remains. While no beds remain in southern California bays, making this habitat functionally extinct, remnant populations do exist at low densities. Although restoration is common along the west coast in Washington, Oregon and northern California, restoration managers have no information about the genetic structure of the Olympia oyster and therefore cannot include this information when designing and planning restoration projects. Genetic analysis can be used to determine appropriate restoration techniques for different populations so that time, resources, and money are used effectively.

My thesis has three main research goals. The first goal is to test for the number of distinct O. lurida populations in southern California and to provide baseline genetic diversity and structure estimates. This will be done using non-coding mtDNA and microsatellites. I will be examining eight sites (from north to south): Mugu Lagoon, Alamitos Bay, Newport Bay, Agua Hedionda Lagoon, Batiquitos Lagoon, San Diego Bay, Mission Bay, and the Tijuana River. The second goal is to combine southern California microsatellite data with data from WA sites and from San Francisco Bay in order to get a nearly range-wide perspective on genetic population structure. Lastly, if some degree of genetic structure is found, I will discuss any phylogeographic and connectivity conclusions that affect local sites in southern California as well as along the length of the west coast.