PW18 Field Biological Monitoring of Ecosystem Impairment
Exhibit Hall
8:00 AM - Wednesday
(PW280) Chironomid community, deformities and locomotory activity affected by acid mine drainage.
Janssens de Bisthoven, L1, Gerhardt, A1, Soares, A1, 1 Dept. of Biology, University of Aveiro, Aveiro, Portugal
ABSTRACT- The insect family of Chironomidae (non biting midges) is known to be useful in biomonitoring and ecotoxicology of all kinds of freshwaters due to its four aquatic larval stages, the easy handling in the laboratory and the high species richness. This was tested on an acid mine drainage (AMD) in southern Portugal, in a dynamic pH/metal gradient spanning a pH range between 3.3 and 6.4, a small reservoir containing arsenic and an unpolluted river in the same ecoregion. Even at the level of subfamily, which can be tackled by the non-specialist, the community differentiated clearly between the sites, with a preponderance of the more tolerant detritus-eating Chironominae and predatory Tanypodinae in the sites affected by AMD. Despite the arsenic, a rich lentic community was found in the reservoir. The community response to AMD involves replacement of sensitive species by tolerant ones, and changes in the food web structure. Deformities of the head capsule were found in a few Tanypodinae species, but were of limited statistical use because of low numbers of larvae. On-line measurement of locomotion of Chironomus larvae with the Multispecies Freshwater Biomonitor to AMD in the laboratory and the field, and to acid-only treatments showed (1) the extreme tolerance of these larvae to AMD, (2) increasing passivity with decreasing AMD-pH and (3) increasing activity at pH 4.4 and 5.5 (in acid-only). This indicates that AMD toxicity is modulated by both the acidity and the metals. Chironomidae were useful at the community, the species and the organism level to assess acid mine drainage
Key words: acid mine drainage, chironomidae, biomonitoring, behaviour