Carin Ashjian
Arctic projects
Antarctic projects
Other projects
CV (pdf format)
Arctic Projects
SHEBA | SBI Food Webs | SBI Shelf-Basin Exchange

Mesozooplankton-Microzooplankton Food Webs
Barry Sherr and Ev Sherr, Oregon State University
Carin Ashjian, Woods Hole Oceanographic Institution
Robert Campbell, University of Rhode Island

A central goal of the Shelf-Basin Interactions (SBI) program is to understand the processes affecting carbon transformations and fluxes within and between Arctic shelf and basin ecosystems, and how climate change might impact these processes. The cycling of carbon in Arctic shelf and basin habitats depends on the structure and functioning of the food webs of these regions. In the pelagial, both micro- and meso- zooplankton are significant consumers of primary production. The partitioning of primary production between the fractions remaining in the water column or sedimenting to the benthos (where organic matter is less available for export from the shelf) can be greatly affected by the relative grazing rates of microzooplankton versus mesozooplankton herbivores. Microzooplankton grazing dampens export flux, while mesozooplankton grazing enhances it.

The primary focus of our proposed collaborative project is an analysis of the impact of microzooplankton and mesozooplankton grazers on the fluxes and exchanges of carbon within the oceanic waters of the Canada Basin and the shelf waters of the Chukchi/Beaufort Seas. We are using standard methods and experimental protocols to determine the standing stocks and size structures of microzooplankton, phytoplankton, and mesozooplankton assemblages, to measure growth (microzooplankton) and reproduction (mesozooplankton) rates, to measure grazing rates of heterotrophic protists and dominant mesozooplankton in the two regions, and to identify mesozooplankton that are sentinel species of Arctic change. Our collaborative study explicitly addresses trophic linkages previously unexplored in this region of the Arctic. We hypothesize that changing ecosystem structure, such as might occur during climate change, will alter the role of these trophic interactions in the utilization and cycling of carbon in arctic shelves and basin systems.

We participated in two six-week cruises to the Chukchi/Beaufort Seas in the spring/summer of 2002 and conducted a series of successful mesozooplankton-microzooplankton grazing experiments as well as numerous egg production experiments with the dominant copepods. We plan to participate on two more such cruises during 2004.

This project is funded by the National Science Foundation.
back to top Biology Homepage | WHOI Homepage