Modeling the Transport Success and Retention of Anchovy (Engraulis anchoita) Early Stages in the Southern Brazilian Shelf

VAZ, A. C.; PARADA, C.; PALMA, E. D.; MUELBERT, J.; CAMPOS, E. J. D.

New Orleans, USA

Congreso; AGU Joint Assembly; 2005

merican Geophysical Union

Eggs and larvae of about 88 fish species distributed among 48 families occur in the plankton community in this area. The processes involving the circulation in this area and its influence on eggs/larvae transport are poorly understood. Recent studies described the spawning activity of anchovy relating it to oceanographic processes. These studies suggest that the predominant onshore Ekman transport, which occurs mainly in the winter and spring periods, keeps the eggs and larvae in coastal areas. It is also known that the continental runoff is a primary factor to the formation of a retention zone for planktonic organisms over the SBS. The formation of a stagnant zone, where the residual currents are weak, favors the patchiness character of plankton communities and nutrients. In our ongoing study we investigate with data and model the dispersion pattern of eggs/larvae of Engraulis anchoita in this region, considering both biological and physical processes. In the modelling approach, surface velocity fields from runs with the Princeton Ocean Model (POM) are used as input data for an Individual Based Model (IBM). This IBM treats every single particle as an individual with its own features, tracking particles (eggs/larvae) trajectories using a Runge-Kutta scheme for spatial interpolation. The analyses of our preliminary results seems to confirm the expected pattern