Invertebrate colonization on Eucalyptus camaldulensis Dehnhardt leaf litter breakdown in an anabranche of the Middle Parana River

Abstract

Eucalyptus camaldulensis leaves collected at abscission and 6 g dry weight were placed innylon bags of 5 mm mesh net in a secondary channel of Middlle Parana River (31º 40`S y 60º 33` W). Three replicates were collected after 7, 14, 28, 56 and 112 days during low water level (may-september 2002). The decay coefficient (k) calculated over 112 days was 0.0131 d-1. The time estimated for 95% of leaves decomposition was 36 days according to the k obtained. The highest invertebrate density (600 ind.g-1 of leaves dry weight) and taxonomic richness (39 taxa) were obtained at 112 days and 14 days of leaf decomposition, respectively. The colonization on decomposing leaves was dominated by chironomids and mussels. Gatherers-collectors (Naididae and Chironominae) were dominant during the first time and filterers-collector (Limnoperna fortunei) increasing at the end of colonization experiment. The shredders (Polypedilum spp.) were more abundant in the first and media colonization phases.