BONETTO Carlos Alberto
Do riparian buffers protect stream invertebrate communities in South American Atlantic Forest agricultural areas?
HUNT, L; MARROCHI, N.; BONETTO, C.; LIESS, M; D. BUSS; VIEIRA DA SILVA, C.; CHIU, M; RESH, V.
Lugar: Berlin; Año: 2017
We investigated the influence and relativeimportance of insecticides and other agricultural stressors indetermining variability in invertebrate communities in smallstreams in intensive soy-production regions of Brazil andParaguay. In Paraguay we sampled 17 sites on tributaries ofthe Pirapó River in the state of Itapúa and in Brazil wesampled 18 sites on tributaries of the San Francisco River inthe state of Paraná. The riparian buffer zones generallycontained native Atlantic forest remnants and/or introducedtree species at various stages of growth. In Brazil the streambuffer width was negatively correlated with sedimentinsecticide concentrations and buffer width was found tohave moderate importance in mitigating effects on somesensitive taxa such as mayflies. However, in both regionsinsecticides had low relative importance in explainingvariability in invertebrate communities, while varioushabitat parameters were more important. In Brazil, thepercent coverage of soft depositional sediment in streamswas the most important agriculture-related explanatoryvariable, and the overall stream-habitat score was the mostimportant variable in Paraguay streams. Paraguay andBrazil both have laws requiring forested riparian buffers.The ample forested riparian buffer zones typical of streamsin these regions are likely to have mitigated the effects ofpesticides on stream invertebrate communities. This studyprovides evidence that riparian buffer regulations in theAtlantic Forest region are protecting stream ecosystemsfrom pesticides and other agricultural stressors. Furtherstudies are needed to determine the minimum buffer widthsnecessary to achieve optimal protection.