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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. |
