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Effects of agricultural landscapes and land uses in highly biodiverse tropical streams of the Ecuadorian Choco

Abstract:

The ecosystem-level consequences of agricultural land use in Neotropical forests have not been fully studied. In areas like the Choco-Darien, conflict exists between the conservation of highly diverse ecosystems and the use of economically important production areas. Current agricultural practices involve complete deforestation, with consequent multiple effects on stream ecosystems. To address the issue of land use change in tropical rivers of Ecuador, we studied streams draining 3 different land use types in the Mashpi River drainage (Ecuadorian Choco): (1) pristine montane cloud forest, (2) organic farms that included forest patches, and (3) palmito (Bactris gasipaes) production land with extensive use of the insecticide endosulfan and the herbicide glyphosate. We sampled macroinvertebrates (quantitative and qualitative samples) and periphyton, and measured environmental variables during dry and wet seasons, and found a direct relationship between the decline of certain macroinvertebrate groups (e.g., Anacroneuria, Hyallela) and the type of land use. Furthermore, we found that species loss in streams draining organic farms was negligible. Species richness of macroinvertebrates was considerably lower in palmito monoculture farmlands than in the other 2 types of land use. Stream communities of the Mashpi drainage area have been transformed by human agricultural disturbances, and urgent changes to land management practices are necessary.