INFORME TECNICO FREPLATA

GIBERTO, D.A.; BREMEC, C.S.

2002-03-01/2003-03-31

1-48

Biológica

Rec.Nat.Renov.-Conservacion y preservacion

The main objectives of this report are to analyze the infralittoral benthic assemblages of the Río de la Plata and adjacent marine zones, and establish broad patterns of species diversity throughout the study area. Species richness was utilized as a measure of diversity. The report was divided in two major approaches: the analysis of an historical background and the EH-09-99 survey. The taxonomic groups that contributed with the major number of species were the mollusks, crustaceans, polychaetes, echinoderms and coelenterates. A classical gradient of increasing species richness from mixohaline to marine waters was found. Also, few species were found inhabiting both mixohaline and marine waters. The species richness values were high at the continental shelf and the coastal marine environments. The highest number of species was recorded in mussel beds and coarse-sandy bottoms marine assemblages. The irregular pattern of species richness found in marine waters could be due to the presence of different heterogeneous bottom types all over the study area. It is concluded that the available information about benthic communities inhabiting the study area is scarce. In addition, a large portion of the studies were developed mainly on the marine zones < 50 m, while the mixohaline zones and the marine zones > 50 m are underestimated. Basic information related with diversity like abundance, biomass, dispersal and temporal variations of macrobenthic species are needed.