GLOBEC 2000: Spatial and Interannual Variation of Microzooplankton: an Ancillary Retrospective Analysis and Sampling Component of the Long Term Observation Program in the Northern California Current System.
B. F. Sherr and E. B. Sherr (both at Oregon State University)

Microzooplankton, grazing organisms <200um in size, have a central role in marine pelagic food webs, and have been identified as a missing component of the GLOBEC Northeast Pacific (NEP) program. The microzooplankton size class is dominated by phagotrophic pritists: ciliates, heterotrophic dinoflagellates, and other flagellates, which are significant consumers of phytoplankton and are a major food resource for larger zooplankton. We propose to provide detailed information on microzooplankton stocks in the GLOBEC California Current System (CCS), in the context of physical, chemical, and biological data collected in the CCS Long Term Observation Program (LTOP). We will document temporal (seasonal and interannual) and spatial (along-shore and from coast to offshore) variability in distribution of microzooplanktonic protists in the CCS. Specific objectives of our research are: 1) Retrospective analysis of microzooplankton stocks in the CCS from samples collected along the Newport (NH) line off Oregon in September 1997 during a strong El Niño, and in September 1998 after relaxation of the El Niño event. 2) Seasonal/regional sampling of microzooplankton stocks in the CCS as part of the LTOP program through September 2003. 3) Analysis of spatial and interannual variability in microzooplankton stocks with respect to environmental parameters collected as part of the LTOP cruises, and 4) Estimating potential rates of herbivory by microzooplankton, and their significance as a food resource to mesozooplankton, for use in CCS food web models.

To facilitate comparison of our results with other microzooplankton data collected in the NEP region, we will process two types of samples: sample sets preserved with a a high concentration of Lugol's solution and inspected via inverted microscopy (optimal for enumeration of ciliates), and samples sets preserved with aldehyde fixative, stained with the fluorochrome DAPI, settled onto filters, and inspected via epifluorescence microscopy (optimal for enumeration of heterotrophic dinoflagellates, other flagellates, and mixotrophic ciliates). Data will include abundance and carbon biomass of general taxonomic groups of microzooplankton, and observations of ingested prey in protist food vacuoles and of the abundance of mixotrophic ciliates. Results from the retrospective analysis of microzooplankton standing stocks, and from our sampling program during the LTOP cruises in 2000-2003 will be processed, archived and disseminated to other GLOBEC investigators as the data become available. The results of this study will provide valuable data on the response of microplankton in upwelling systems to El Niño events, in the context of other data already collected in the CCS during the 1997-1998 El Niño. Our study will also provide important information for CCS ecosystem modelers, and will add to comparisons of CCS and Coastal Gulf of Alaska (CGOA) ecosystem dynamics.

This page was last updated on September 22, 2000.

Maintained by:
Hal Batchelder [hbatchelder@coas.oregonstate.edu
College of Oceanic & Atmospheric Sciences
Oregon State University
Corvallis, OR 97331-5503
phone: 541-737-4500; FAX 541-737-2064