Benthic invertebrate assemblage along a brackish plain river in South America (Samborombón river, Argentina)

SPACCESI, F.; RODRIGUES CAPÍTULO A

Aquatic Ecology

Kluwer Academic Publishers (SPRINGER)

Lugar: The Netherlands- Amsterdam ; Año: 2009 p. 1011 - 1022

1386-2588

Abstract: Structure and composition of benthic invertebrates was studied in 3 sites of the Samborombón River. It is an important tributary of the Río de la Plata estuary (Argentine) with a low slope and brackish drainage. Biological samples were taken seasonally with Ekman and Veen grabs. Physic-chemical variables were measured to determine which environmental factors are better associated to the distribution of the benthic fauna. The site 1, in the headstream, was characterized by freshwater pampean organisms. The site 2, with a high conductivity (3.5 ± 2 mS cm-1), showed the highest density, diversity, and richness. Brackish species, as Leaonereis culveri, were found here. The site 3, close to the Samborombó Bay, was characterized by an unstable taxonomic composition, strongly influenced by the estuary. The densities and diversity of organisms there were the lowest registered and there were distinguished by estuarine species. Multivariate method (Redundancy Analysis) showed that the benthic groups had got an important spatial variability associated with the salinity gradient of the river, superimposed to the temporal variability. This environmental characteristic of the drainage, suggest and offer the opportunity to research with salinity sensible taxa, in each part of the Samborombó River.