A biophysical model of the interaction between vertical migration of crustacean zooplankton and circulation in the Lower St. Lawrence Estuary

• Published in: Canadian Journal of Fisheries and Aquatic Sciences
• Main Authors: Zakardjian, Bruno A, Runge, Jeffrey A, Plourde, Stephane, Gratton, Yves
• Format: Article in Journal/Newspaper
• Language: English
• Published: Canadian Science Publishing 1999
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Canada; Calanus finmarchicus; Copepods
• Online Access: http://dx.doi.org/10.1139/f99-095; http://www.nrcresearchpress.com/doi/pdf/10.1139/f99-095

As an essential step in modeling the influence of circulation on the population dynamics of marine planktonic copepods, we define a simple formulation of swimming behavior that can be used in both Eulerian and Lagrangian models. This formulation forces aggregation of the population toward a preferential depth and can be stage specific and time varying, thus allowing description of either diurnal or seasonal vertical migration. We use the formulation to examine the interaction between the circulation and vertical distribution in controlling horizontal distribution of the common planktonic copepod Calanus finmarchicus in the Lower St. Lawrence Estuary, Canada. We first introduce diel migration into a simple one-dimensional model and then into a model of residual two-dimensional circulation patterns representative of conditions encountered in the Lower St. Lawrence Estuary. Results from the latter indicate that interactions between circulation and stage-specific swimming behaviors are the main mechanisms for aggregation of planktonic crustaceans at the head of the Laurentian Channel and highlight the implications of flushing of the surface-dwelling young stages for the population dynamics of C. finmarchicus in the Lower St. Lawrence Estuary.