WIND INFLUENCE IN THE OYSTER LARVAE TRANSPORT WITHIN A COMPLEX BAY: ANEGADA BAY, ARGENTINA

ALVAREZ, LAURA I.; ALBERDI, ERNESTO; CUADRADO, DIANA G.; PERILLO G.M.E.

Iguazú

Congreso; 2010 Meeting of Americas. AGU; 2010

AGU

Crassostrea gigas is an invasive species within the Argentina coast,in particular, within Anegada Bay (between 39° 50’ and 40° 40’ S).However, many of their banks are being exploited for commercialactivities and, recently, aquaculture developments have started. A majorproblem is the potential migration of the larvae outside Anegada Baytowards the San Matías Gulf where the local oyster is being conserved. C.gigas outcompites the local oyster resulting in the potential eliminationof the original one. The present study provides the results of a numericallangrangean model of the circulation of the bay including thedisplacement of the larvae by tidal currents but also as they are affectedby the typical wind pattern of the region. Anegada Bay is a complexsystem of tidal channels, extensive coastal wetlands and islands. Thesystem is mesotidal with ranges between 2 and 3.5 m. Although thedominant wind pattern is from the NW and SW most of the year, duringthe larvae hatch (summer period) the predominant wind is from the NNEand NE with mean speeds of the order of 34 km/h. Mean watertemperature is 20°C, and typical current velocities in the San BlasChannel may reach up to 2 m/s. We employed the 3D hydrodynamicmodule of the MOHID model plus its langrangean biological module witha resolution of 100 m and 15 levels using a sigma configuration. Themodel was run for a period of 90 days during the warm months of thesouthern hemisphere using as external tidal forcing the Fes 2004 model.Model validation and calibration was made against tidal and wind datafrom two EMAC stations operated by IADO on site plus ADCP dataobtained along a tidal cycle on a cross section of the San Blas Channel.The results of the model show that larvae are retained within the bay andin many cases they are forced along the inner tidal channels of the bay.It is clear that if the wind pattern is maintained, the larvae do notrepresent a danger to the local oysters within the San Matias Gulf.