PREELIMINARY RESULTS ON FISH ASSEMBLEGES IN (AANEGADA BAY RGENTINA).

MOLINA J. M.; LÓPEZ CAZORLA A. C.; CUADRADO D.; LLOMPART F.; COLAUTTI D.; BAIGÚN C.; SUQUELE P.; CALVO S.; OÑATIBIA H.

Bahia Blanca, Buenos Aires, Argentina

Simposio; ECSA 44 Symposium: Science and management of estuaries and coasts: A tale of two hemispheres,; 2008

Estuarine and Coastal Sciences Association , Instituto Argentino de Oceanografía

Anegada bay, located in Buenos Aires, Argentina has an important ecological value due to a great biodiversity in a high environmental complexity. The present study shows preliminary results from the structure of the fish assembles in the southern region of this bay. The study zone is characterized by a 27-m deep tidal channel where two stations were placed. One is closed to an island on the northern flank, SB, where the bottom sediment is characteristically inconsolidated sand. The other station was placed on the southern flank in Los Pocitos (LP), in the inner part of the bay, where vegetated salt marshes and also consolidated fine-sand sediment is found. The surveys were performed seasonally during December 2007 ? May 2008, using gillnets. The frequency of occurrence was estimated for each species. The diversity index (H?) was calculated in order to characterize the fish assemble and evaluate spatial differences. During the three surveys conducted, 17 species were registered, being Mustelus scmitti, Squatina sp., Odontesthes argentinensis and Cynoscion guatucupa the most frequent (100%). From the total number of species captured, 88% were present in SB and 70% in LP. From the total, 41% appeared only in one site, from which 29% were in SB and the 12% in LP. Diversity showed important spatial differences: LP presents higher H? values than SB, 1.9 and 1.1 respectively. The differences found between the two sites, can be related with the different environments. While LP represents a low-energy environment with finer bottom sediments, SB presents inconsolidate sand. These sedimentological differences can affect the food supply for fish community. Keywords: Fish distribution, sedimentological differences, Anegada bay