Colonisation of low- and high-quality detritus by benthic macroinvertebrates during leaf breakdown in a subtropical stream

Abstract

Abstract Leaf litter in streams is exploited by benthic macroinvertebrates, and leaf traits may influence colonisation by this group. This study aimed to compare the leaf decomposition rates, structure, and composition of the macroinvertebrate fauna colonising the litter of plant species with contrasting leaf traits. Litter bags from two native plant species ( Sebastiania brasiliensis and Campomanesia xanthocarpa ) and two non-natives ( Hovenia dulcis and Platanus × acerifolia ) were incubated in a subtropical stream. After 7, 14, 21, and 28 days, four leaf bags for each species were removed, and the leaf decomposition rates, density of organisms and trophic guilds, taxonomic richness, and functional composition of the macroinvertebrates were compared. The decomposition rates and densities of organisms, shredders, and collector–gatherers were higher for the leaves considered to be better quality, with lower C:N and Lignin:N ratios (from S. brasiliensis and H. dulcis ). Additionally, the taxonomic and functional compositions of the macroinvertebrates were different for these leaves. In contrast, the species richness and density of the other guilds showed no significant difference between species. This study shows that detritivorous groups prefer leaves of better quality, and most results may be influenced by the high nutritional content and low amount of compounds that complicate fragmentation, such as tannins, lignin, and cellulose. Therefore, the effects of the replacement of riparian plant species on the local macrofauna depend of the traits of the introduced and replaced plant, regardless of their origin.