January 1, 2019.
Conservation and restoration of natural habitats ensures the establishment of species diversity and richness. In the San Francisco Bay, local efforts have been enacted to replenish the Olympia oyster population (Ostrea lurida) whose numbers are dwindling due to the presence of an invasive, non-native whelk, the Atlantic oyster drill (Urosalpinx cinerea). The goal of this study is to better understand the effects of the oyster drill on the local marine population in Richardson Bay by examining the recruitment and survival of the Olympia oyster. The initial absence of oyster recruits required the use of the local barnacle species (Balanus and Chthamalus) as a proxy, looking at the effect of tidal elevation on the recruitment and survival to better understand the ecological pressures faced by other organisms living in similar ecological conditions. Twelve PVC frames were placed in the intertidal zone at our study site, Richardson Bay, in predetermined elevations: +0.5 feet, +1.5 feet, and +2.5 feet above mean lower low water. Each frame held three porcelain tiles and was either a ‚ÄúRecruitment‚Äù or ‚ÄúSurvival‚Äù frame (two of each type at each tidal elevation). Every two weeks, tiles from each frame were retrieved, with ‚ÄúRecruitment‚Äù frames receiving new tiles; ‚ÄúSurvival‚Äù tiles were returned the following day to their respective frame. Tiles were examined under the microscope for the presence of oysters, oyster drills, and barnacles and these data were recorded on specified datasheets; this process occurred for a total of six weeks. Analysis showed the highest recruitment and the highest survival at the +2.5 tidal elevation, while barnacles recruited in the lowest numbers at +0.5 and had the least survival at +1.5. While these conclusions align with ongoing studies, a small sample size complicates the power of this study and considerations have been offered for added power of future studies.
Andrew Chang, Chela Zabin
San Francisco State University (SFSU)
The 2018 STEM Teacher and Researcher Program and this project have been made possible through support from Chevron (www.chevron.com), the National Marine Sanctuary Foundation (www.marinesanctuary.org), the National Science Foundation through the Robert Noyce Program under Grant #1836335 and 1340110, the California State University Office of the Chancellor, and California Polytechnic State University in partnership with San Francisco State University. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the funders.