Microbial effects in leaf breakdown in tropical reservoirs of different trophic status

Abstract

AbstractThe objective of our study was to compare leaf breakdown rates (k) and the influence of microorganisms and aquatic invertebrates on mass loss of Eichhornia crassipes (Mart.) Solms and Typha domingensis Pers in 2 reservoirs (eutrophic and oligotrophic). We hypothesized that k would be higher in eutrophic than in oligotrophic conditions because of increased microbial activity in eutrophic conditions. We collected green leaves, which we air-dried, weighed, placed in litter bags, and incubated in each reservoir. We calculated k (negative exponential model) for each species in each reservoir. We characterized initial leaf chemistry, estimated total microbial biomass (as adenosine triphosphate [ATP]) and fungal biomass (as ergosterol), and evaluated invertebrate community composition and structure. Both species decomposed faster in the eutrophic reservoir. During leaf breakdown, bacteria were more important in the eutrophic reservoir, whereas fungi were more important in the oligotrophic reservoir. Inve...