Abstract

MARTINEZ, Dina Elsa. Modern ostracod assemblages from the Bahía Blanca estuary, Buenos Aires, Argentina. Ameghiniana [online]. 2005, vol.42, n.4, pp.669-684. ISSN 1851-8044.

This paper deals with the ostracod assemblages recovered from superficial sediments of the Tres Brazas Channel of Bahía Blanca Estuary. The distribution of biocoenosis and autochthonous thanatocoenosis allowed to recognize different habitats. The species developed in tidal flats are Loxocythere variasculpta , Neocytherideis ruidis , Cyprideis salebrosa hartmanni , Leptocythere darwini ?, Cytherura dimorphica , Frenguellicythere argentinensis and Paracytherois sp. n. In subtidal areas Callistocythere litoralensis , Hemicyherura escobasensis , Cytheretta punctata , Cornucoquimba lutziana , Semicytherura rugosoreticulata and Hemicytherura chuiensis were recognized. The faunal composition and quantitative variations of the ostracods can be correlated with the topography, sedimentology, vegetation and variations of salinity in the tidal flats, whereas the energy is the most important factor in subtidal areas. The quantitative distribution of allochthonous ostracods shows highest relative abundances in sediments from the channel, reflecting the environmental hydrodynamic. The erosive flank of the channel is characterized by paleothanatocoenosis originated in ancient tidal flat deposits.

Keywords : Modern ostracods; Environmental factors; Bahía Blanca estuary; Buenos Aires; Argentina.