R. Patrick Hassett, Ohio University with Pamela Blades-Eckelbarger, University of Maine (subcontract) One of the target species of the GLOBEC Georges Bank program is Calanus finmarchicus, a dominant copepod of North Atlantic waters. A key feature of this copepod s life cycle is the period of dormancy undergone in the fifth copepodite stage (CV), a period which lasts from late summer through early winter. As the dormant population of CV s in the Gulf of Maine appear to fuel the spring population increase on Georges Bank, understanding the process of dormancy may be an important component to understanding the seasonal population dynamics of this species.
This project will address the following questions related to dormancy in Calanus:
Laboratory experiments at the Darling Marine Center will determine the effect of temperature on lipid utilization and the relationship between physiological measurements and a. gonad state and b. respiration rates and lipid utilization. The first objective will be to develop a protocol to analyze the biochemical composition (lipid, soluble protein, RNA, DNA) and enzyme activities (digestive laminarinase, carnitine palmitoyl transferase, and/or citrate synthase) of individual Calanus finmarchicus utilizing a microplate fluorometer. The value of multiple measurements on an individual is that the proposed measures are tied to different aspects of the animal s physiology: i.e. fuel storage system, digestive system, reproductive system (gonad state), each of which may respond with a different timing and at a different rate during dormancy.
The field program will involve sampling of overwintering populations of Calanus finmarchicus in the deep basins of the Gulf of Maine, to be conducted jointly with other GLOBEC participants, and in nearshore waters off the mouth of the Damariscotta River. The laboratory observations will then provide a basis for assessing the physiological status of the field populations.