Benthic invertebrate assemblages and functional feeding groups in the Paraná River floodplain (Argentina).

ZILLI, FLORENCIA LUCILA; MONTALTO LUCIANA; MARCHESE MERCEDES ROSA

LIMNOLOGICA

Elsevier

Año: 2008 vol. 38 p. 159 - 171

0075-9511

The benthic invertebrate assemblages and functional feeding groups in different mesohabitats of the Middle Parana´River?floodplain system were analyzed. Benthic invertebrates and bottom sediments were sampled in a secondarychannel (center and bank mesohabitats), a temporal marginal fluvial wetland adjacent to the river, an isolated lake anda connected lake during low water level. Cluster analysis of average invertebrate densities based on the Bray Curtisdissimilarity index yielded a group composed by the mesohabitats with higher species richness, the floodplain lakes,banks mesohabitats and the wetland. The center mesohabitat of the main channel characterized by sandy sedimentswith low organic matter content and the lowest invertebrate densities and species richness was classified separately.Alpha diversity increased from the center mesohabitat (6 taxa) to the adjacent wetland (71 taxa), and were similarbetween the floodplain lakes (24 and 22 taxa) and the river bank mesohabitat (24 taxa). Gamma and beta diversities(Whittaker index) were 92 and 2.19, respectively. The highest turnover of taxa was between the river and the othermesohabitats and the lowest between floodplain lakes. Detrended correspondence analysis (DCA) showed a clearseparation of wetland and banks from other mesohabitats (axis 1 and 2 explained 52.25% variance) explained byshredders and collector-filterers. The other mesohabitats were arranged in a gradient from the main channel mostlyrelated to collector-gatherers to the connected lake and the isolated lake that were mostly characterized by predatorsand scrapers. The invertebrate assemblage complexity and functional feeding groups composition increased in thelateral dimension, from the center of the main channel to the temporal marginal fluvial wetland due to the influences ofthe spatial heterogeneity caused by different sources of organic matter inputs.