LEAF LITTER WITH CONTRASTING CHEMICAL TRAITS AND DECOMPOSITION PROMOTE SIMILAR BENTHIC MACROINVERTEBRATES COMMUNITIES

Abstract

In aquatic ecosystems, allochthonous inputs of leaf litter are common substrates for the invertebrates communities. The quality and physical structure of these substrates are expected to strongly determine benthic invertebrates structure and functioning. Therefore, we carried out an experiment to evaluate the association between these organisms and the chemical traits of leaf litter from 16 restinga plant species in Jurubatiba lagoon, a coastal aquatic ecosystem at Restinga de Jurubatiba National Park. After 123 days, litter mass loss varied from 14 - 30%, indicating that decomposition was in the initial stage for most species. Litter converged to have a similar nutritional quality after this time submerged. Initial K concentration positively affected, whereas initial lignin and C concentration negatively affected species richness and diversity. It indicates that nutrients attract whereas structural compounds limit benthic species colonization. Chemical compounds such as C, nutrients (N, P, K and Na), lignin and cellulose tended to be positively associated with the dominant taxa (Chironominae n.i. and Heleobia australis) and functional feeding groups (scrapers and collector-gatherers). However, no significant associations were detected by the redundancy analyses. We may conclude that litter quality affect benthic structure, but not community composition nor FFG distribution at Jurubatiba lagoon. The benthic composition and FFG may be randomly distributed among litter substrates or may be better explained by some other litter aspect(s) different from those considered in this study. Future studies may also consider the temporal dynamic of litter colonization to better elucidate the relationship between litter traits and invertebrate community.