CERITHIDEOPSIS CALIFORNICA AS A SEA-LEVEL INDEX TOOL FOR THE SOUTHERN CALIFORNIA COAST

Relative sea-level (RSL) curves are required for better understanding and predicting future effects of sea-level rise on coastlines. In California, records of past sea level also provide excellent datums for determining rates of vertical tectonic motion. However, only one regional tectonically corrected RSL curve is available for the entire US Pacific Coast, and this curve has uncertainties of up to 3 m. One challenge for reconstructing past RSL is identifying suitable methods for doing so. In this study we examine the utility of the gastropod, Cerithideopsis californica, formerly known as Cerithideopsis californica for its use as an RSL indicator. We measured its distribution in two southern California estuaries in the fall, winter, and spring seasons. We find that Cerithideopsis californica inhabits elevations of -0.42 to 0.63 m (relative to mean sea level) in Carpinteria Salt Marsh and -0.31 m to 1.00 m in Tijuana Estuary, and thus provides a valuable sea level-index point for the reconstruction of past relative sea levels. Furthermore, we obtained a radiocarbon age of 1530-1781 BP from a C. Californica specimen within a core from Los Penasquitos Lagoon in San Diego, CA. This value fits within the uncertainty bounds of previous RSL curves created for Southern California. Our new relative sea-level record will provide a valuable datum for determining rates of vertical motion along the southern California Coast.