BENTHIC MACROINVERTEBRATE COMMUNITIES RESPONSE ON THE FINE SEDIMENT ACCUMULATION IN MOUNTAIN STREAM

Forestry is often associated with an increase rates of soil erosion and sediment transport, and forest roads facilitate the flow of sediment particles to streams. The aim of the study was ecological status assessment of the stream exposed to silting, based on benthic invertebrates responses. The research was carried out in the Tym Stream, which is a mountainous stream with a rather large slope and pebble-gravel bottom. Changes in channel of the stream were associated with the accumulation of fine sediments. Sources of sediments in the stream were mainly forest roads and trails. There were 4 sampling sites: two in the zone of sediments accumulation and two in the sections of the stream that were not silted. Morphological and physico-chemical parameters were measured. The main object of the study was macrozoobenthos. The accumulation of fine sediments worsen the living conditions of natural communities of invertebrate fauna, especially invertebrates associated with stony bottom and quickly flowing water like stoneflies, mayflies and caddisflies. Siltation of the substrate decreased the variety of the habitats. In the community of benthos in silted sites chironomid larvaes and oligochaetes dominated.