Abundance, Biomass, Vertical Distribution and Selected Process Studies of Arctic Ocean Zooplankton: A Collaborative Proposal for Ancillary Use of the SHEBA Platform

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This collaborative research project represents one of the first comprehensive biological process studies to be carried in the Arctic Ocean over a full annual cycle. Investigators from Woods Hole Oceanographic Institution, University of Rhode Island, and Brookhaven National Laboratory, the Canadian Dept. of Fisheries and Oceans, and from other U.S. institutions will use a Canadian icebreaker as home base for a 14-month period to study the seasonal cycle of biological production and respiration, and the seasonal cycle in biomass of algae, bacteria, protists, and zooplankton, in the central Arctic. This project involves a year-long study of the distribution and abundance of total zooplankton and standing stock, vertical migration patterns, and aspects of secondary production and vital rates of four target copepod species, including egg production, egg viability, growth, and changes in carbon standing stock, in the upper 500 m of the Arctic Ocean. Additionally, the carbon and energy flow at the over-wintering site will be described. The sampling plan includes both continuous (acoustic) and weekly (net tows) monitoring of zooplankton biomass and abundance augmented by periodic, intensive, process oriented work: 1) Acoustic backscatter intensity data will be made available periodically to calibrate the backscatter intensity: zooplankton biomass relationship using total zooplankton biomass measured from net hauls. 2) Zooplankton biomass, abundance, and taxonomic composition will be measured at ~10 day intervals throughout the period of the project. Vertically discrete samples will be collected at regular but less frequent intervals (monthly) using opening/closing mechanisms on the ring nets. 3) Process Studies will involve egg production rate and viability experiments, growth rate experiments, and taxa and life stage specific determination of respiration rates for the dominant copepod species. Individuals of the dominant taxa will collected for length, dry weight, carbon and nitrogen content and the determination of the RNA/DNA ratio, an indicator of the vital rates of the copepods. The results will be compared to those from previous studies and will enhance understanding of the Arctic Ocean ecosystem, the life cycles of copepods in the Arctic Ocean, variability in the Arctic ecosystem, and the potential importance of zooplankton, especially copepods, to the Arctic Ocean carbon cycle. The seasonal study of production/ respiration processes will provide valuable information regarding: 1) the present structure and function of central Arctic ecosystems, which can serve as a baseline for evaluating the impact of future global change processes in this sensitive region; and 2) the nature and timing of production and respiration processes in a high latitude system and in particular how the heterotrophic community survives during the dark winter months.