Effects of Bridges construction on the benthic invertebrates structure of the Delta Paraná River

Abstract

Benthic assessment of lotic environments impacted by bridge and highway construction at the Paraná River Delta is reported. The purpose of the study was to examine the degree of impact of physical disturbances on benthic invertebrates of four secondary channels (Carbón Chico, Carbón Grande 1, Carbón Grande 2 and Paranacito Victoria Rivers). The cluster and DCA analyses showed two groups of habitats based on the grain size sediments and organic matter content. The sites with silt-clayed (mainly upstream from the bridges) showed higher species richness, diversity and benthic biomass than the sites with sandy sediments (under and downstream from the bridges) where the highest densities reached by Narapa bonettoi and Myoretronectes paranaensis were obtained. Although the bridge construction has affected the benthic structure due to the erosion process of bottom sediments, the typical r-strategist species assemblage related to sandy unstable sediments in Paraná River colonized the habitat successfully within less than one year after disturbances.