Report of the

U.S. GLOBEC Georges Bank

Science Meeting

18 - 20 November 2003, Rhode Island

 


Cover Page

Acknowledgements

Introduction

Narrative

Presentation Abstracts

Poster Presentations

Appendix I: Agenda

Appendix II: List of Participants

Appendix III: List of Planned Publications


Dynamics of Calanus finmarchicus Resting Populations in the Gulf of Maine

Saumweber, W.1
1Graduate School of Oceanography, University of Rhode Island, Narragansett, RI 02882

The calanoid copepod, Calanus finmarchicus, dominates epipelagic mesoplankton biomass in the Gulf of Maine from January to June. It is currently believed that this large spring population develops primarily from a seed population of diapausing animals that overwinter in the Gulf of Maine's three deep basins: Wilkinson, Georges, and Jordan. This seed population in turn is thought to consist mostly of animals that developed during the previous spring bloom and have since been in diapause for six months or more. However, recent work with populations of C. finmarchicus in the Eastern Atlantic suggests that the deep water in the Gulf of Maine may be too warm for diapausing animals to survive the required six months. To investigate this possibility, a new nitrogen specific respiration model has been developed for diapausing stage C5 C. finmarchicus in the Gulf of Maine. Stage C5 C. finmarchicus were collected during July and September 2003 from Wilkinson and Georges Basins using both a MOCNESS and the suction sampler of the Johnson Sea Link II submersible. Metabolic rates were measured using Winkler incubation techniques in the field and a Micro-Oxymax gas analyzer on shore. Oxygen consumption rates measured in the field in July and September were not significantly different but were higher than rates measured on shore. In order to predict potential survival time, the shore measured nitrogen specific rate was applied to individual C. finmarchicus from the Gulf of Maine that were caught and measured during the summer and fall of 2001. Results suggest that diapausing animals caught in June have a survival window of two to three months and that significant starvation mortality will accrue by August. Strong changes in the size distribution of C. finmarchicus between June and August and August and November support these predictions and suggest that there is a significant addition of animals to the diapausing population, either from advection or a surface population that is actively reproducing.