Investigating the Effect of Oceanographic Conditions and Swimming Behaviours on the Movement of Particles in the Gulf of St. Lawrence Using an Individual-Based Numerical Model

Abstract

ABSTRACTIn this study an individual-based numerical model with three-dimensional (3D) and time-dependent fields of circulation and hydrography is used to examine the effects of the physical environment and various biological behaviours on the distribution and movement of particles in the Gulf of St. Lawrence and adjacent waters. The 3D circulation and hydrographic fields are simulated by a numerical ocean circulation model. The model domain covers the St. Lawrence Estuary (SLE), the Gulf of St. Lawrence (GSL), the Scotian Shelf, the Gulf of Maine, and their adjacent waters. The basis of the individual-based model is a numerical scheme that tracks the movement of particles carried by ocean currents. Several swimming behaviours of marine animals are considered with efficient seaward migration in the GSL as the goal. Electronic tagging data for the American eel (Anguilla rostrata) are used as guidance in specifying the behaviours. It is demonstrated that particles that undergo an observed behaviour, known as selective tidal stream transport, are able to exit the SLE more efficiently than particles that are carried passively by the 3D ocean currents. Outside the SLE, particles that search for and swim towards higher salinity move further downstream than those that have a preference for deeper water or swim in random directions.