Long-term Variability in Diatom and Dinoflagellate Community Structure of La Jolla Bight: Comparison Between the Early and Late 20th Century

University Of California-San Diego Scripps Inst Of Oceanography, La Jolla CA

Investigators

Abstract

Interannual and interdecadal climatic variations strongly affect the structure and function of marine ecosystems. Long-term studies of the California Current system in the northeast Pacific have shown that climate-ocean variations have disturbed and changed the marine ecosystems off the West Coast of North America. However, in the context of climate-ocean change we know nothing about how phytoplankton, an extremely important component of the food web, are affected. To help fill this gap we propose to build an 8-year time series (1992-2000) to study variability in the biodiversity and abundance of diatoms and thecate dinoflagellates from the Scripps Institution of Oceanography (SIO; 32 50' N, 117 10' W) pier in La Jolla Bight, California. This project will develop a biological database structured to follow Ocean Biogeographical Information System (OBIS) standards for eventual inclusion in the Census of Marine Life (CoML) program. This time series will also provide a high quality record of diatom and dinoflagellate species that can be used to evaluate harmful algal blooms in the region. This dataset will include: (1) a complete list of diatom and dinoflagellate species; (2) updated nomenclature including complete Latin names, synonyms for each species and authorship; (3) a bibliography; (4) species abundance data; (5) documentation on identifications including light microscopy illustrations and to a limited extent scanning electron micrographs. Prepared specimens will also be retained for reference and archiving. The Scripps Pier site is a historical sampling platform with a wealth of information on oceanographic properties measured continuously for two to eight decades. Diatoms and dinoflagellates, are the most completely characterized components of the phytoplankton in the Southern California Bight. A unique historical baseline of information on planktonic diatoms and thecate dinoflagellates is available for the SIO pier, based on W. E. Allen's collections between 1917 and 1939, and additional information is available from semi-continuous surveys during 1950-1974, 1983 and 1997. Thus, this project builds on a unique historical data set for plankton and hydrography of the central California coast. This project will be important in creating a solid, long-term phytoplankton time series dataset that will set the groundwork for future studies related to assessing the effect of climate change on marine phytoplankton populations.