Litter Decomposition can be Reduced by Pesticide Effects on Detritivores and Decomposers: Implications for Tropical Stream Functioning
View/ Open
Date
2021-04-28Author
Cornejo, Aydeé
López Rojo, Naiara
García, Gabriela
Pérez, Edgar
Guerra, Alisson
Nieto, Carlos
Metadata
Show full item record
Environmental Pollution 285 : (2021) // Article ID 117243
Abstract
Understanding which factors affect the process of leaf litter decomposition is crucial if we are to predict
changes in the functioning of stream ecosystems as a result of human activities. One major activity with
known consequences on streams is agriculture, which is of particular concern in tropical regions, where
forests are being rapidly replaced by crops. While pesticides are potential drivers of reduced decomposition rates observed in agricultural tropical streams, their specific effects on the performance of
decomposers and detritivores are mostly unknown. We used a microcosm experiment to examine the
individual and joint effects of an insecticide (chlorpyrifos) and a fungicide (chlorothalonil) on survival
and growth of detritivores (Anchytarsus, Hyalella and Lepidostoma), aquatic hyphomycetes (AH) sporulation rate, taxon richness, assemblage structure, and leaf litter decomposition rates. Our results revealed
detrimental effects on detritivore survival (which were mostly due to the insecticide and strongest for
Hyalella), changes in AH assemblage structure, and reduced sporulation rate, taxon richness and microbial decomposition (mostly in response to the fungicide). Total decomposition was reduced especially
when the pesticides were combined, suggesting that they operated differently and their effects were
additive. Importantly, effects on decomposition were greater for single-species detritivore treatments
than for the 3-species mixture, indicating that detritivore species loss may exacerbate the consequences
of pesticides of stream ecosystem functioning.