How oil palm cultivation is affecting mayfly assemblages in Amazon streams

Abstract

The effects of the implantation of oil palm plantations on a series of environmental variables and the diversity and distribution of mayfly nymphs was investigated through a survey of 23 streams located in areas of plantation and natural forest in the eastern Amazon basin. Composition and richness of mayfly genera were compared among streams in order to verify which genera respond to the habitat disturbance gradient and determine thresholds for each variable. The genera number was higher in forest streams, although genus composition was similar between treatments. Only 9 of the 114 physical variables measured differed significantly between plantation and forest, and only three limnological variables were significantly different. Threshold Indicator Taxa ANalysis indicated that four genera were significantly associated with these variables. Of these, Miroculis and Ulmeritoides were associated with the largest number of variables. Given the different options available for use of soil in the Amazon basin, oil palm plantations appear to be one of the least deleterious for native fauna. In the Brazilian Amazon basin, government-sponsored zoning for the establishment of oil palm plantations as a strategy for the recuperation of degraded land thus appears to be a viable option for the reintegration of areas left damaged by agricultural activities, as long as the process is implemented adequately and monitored systematically. Also, legislation must be respected, in particular the permanent preservation of riparian zones, which may function as effective buffer zones to the runoff of pesticides and sediments.