Pulp effluent effect on benthic macroinvertebrates community of central Chile

摘要

The freshwater aquatic ecosystems are increasingly modified by several different human activities, being relevant industrial effluent discharges, which cause physical and chemical changes in the water column and sediment that result in structural changes in biological communities. Macroinvertebrate communities associated with river water bodies are considered bioindicators of environmental conditions, because they respond to different dynamics of natural and anthropogenic origin. Among the responses to such disturbance are movements of organisms into new areas allow drift in the stream (derived active) or are forced into this process (derived differential). The first is a mechanism that enables restoration of natural systems has been operated, because they are vectors of colonization processes. This behavior can be utilized as a tool to assessment a punctual impact, as drift occurs relatively even across the stretch of a river and offering optimal substrate for colonization, the possibility that they could be colonized, would be the same. This study evaluated the effect of a pulp effluent on macroinvertebrate colonization of artificial substrates (natural substrates previously treated). We compared three sampling areas defined as: pre-impact, impact and post impact (two stations at different distances) for two seasons. The registered macrofauna consisted, mainly immature stages of insects that showed significant differences between the impacted areas and non-impacted (ANOSIM R= 0.51, p＜0.001), increasing the abundance of macroinvertebrates in the areas of impact and post-impact resistant for pollution families (e.g. Chironomidae, Lumbriculidae). The physico-chemical variables also showed significant differences (ANOSIM R= 0.96 p ＜0.001) being the conductivity, BOD_5, dissolved oxygen variables that model the behavior of communities in the impacted areas in both seasons.