Benthic invertebrate structure in wetlands of a tributary of the Middle Paraná River affected by hydrologic and anthropogenic disturbances.

MARCHESE, M. R; RODRIGUEZ, A.R.; PAVÉ, P.J.; CARIGNANO, M.R.

Journal of Environmental Biology

Triveni Enterprises ISSN 0254-8704

Año: 2008 vol. 29 p. 343 - 348

0254-8704

Chromium concentrations in water column and bottom sediments and the main changes produced by human activities and hydrological disturbances as the extreme flooding on benthic invertebrates structure in the main channel of Northern Salado River (tributary of Middle Paraná River) and its wetland floodplain were analyzed. Sediment concentrations of the reference area varied between 44.2 and 97.1 mg Cr g-1 (dw), and in the impacted zone, between 85.5 and 209 mg Cr g-1 (dw) reaching the highest values in the wetland floodplain. Alfa, beta and gamma diversities in the reference section have been 33, 9 and 66 species, and in the disturbed section, they have been 37, 8.33 and 74 species, respectively. The species dominant in the disturbed habitats were characterized by a small body size and short life cycles, as the species of oligochaetes Naidinae. The extreme flooding produced a rejuvenation of the area with the consequent physical re-structuration produced by flooding, showing a marked decrease in chromium levels in sediments and in organic matter content, which allowed the colonization of insects (Ephemeroptera and Trichoptera),