Project Summary

Mark D. Ohman and Edward G Durbin

U.S. GLOBEC: Life History Events of Calanus Finmarchicus (Copepoda) on Georges Bank, A Component of U.S. GLOBEC: Ichthyoplankton and Zooplankton in the Georges Bank Region

U.S. GLOBEC Phase I and II results showed that the abundance and production rates of Calanus finmarchicus and Pseudocalanus spp. differ greatly between the shallow well-mixed crest waters of Georges Bank and the deeper waters of the northeast peak and the southern flank. Dr. Ohman and associates suggest that this smaller scale temporal and spatial variability is controlled by variations in vital rates (recruitment, growth and mortality) and frontal processes on GB (convergences, exchange rates across fronts). They will address these questions through the following specific objectives: (1) Determine spatial and temporal changes in abundance of nauplii of Calanus, Pseudocalanus, and of other copepods on Georges Bank during the winter/spring period as a part of the zooplankton broad-scale survey. (2) Determine the spatial, seasonal and inter-annual variation in egg production, growth rates, physiological condition and mortality for the dominant copepod species including Calanus and Pseudocalanus. (3) Determine abundance, individual growth rates, and physiological condition of the target copepod species, as well as the abundance of other zooplankton species, over fine spatial scales across the crest-southern flank tidal mixing front during late April-early May. (4) Provide the modeling and synthesis groups with data on copepod distribution, recruitment, growth and mortality rates. This project is composed of four separate components which have been combined in one proposal. These components are: (1) the broad-scale pump survey, (2) the egg laying rate measurements of Calanus, Pseudocalanus, and other dominant copepods (3) the growth rate measurements of Calanus and Pseudocalanus, and (4) the estimation of egg and naupliar mortality of Calanus and Pseudocalanus. The pump survey will take place during each of the broad scale survey cruises while the latter three components will be carried out during each of the process cruises although broad scale survey female abundance data will be used in bank-wide egg production estimates.