Aquatic Insects as Bioindicators of Trace Element Contamination in Cobble-Bottom Rivers and Streams

Abstract

Trace element bioaccumulation was studied in immature benthic insects from two contaminated river systems to develop these animals as bioindicators. In one river, Cu, Cd, Pb, and Zn were analysed in insects and in fine bed sediments over a 381-km reach downstream of a large copper mining complex. In the other river, As contamination from a gold mine was assessed in insects and bed sediments over a 40-km reach. All insect taxa collected in contaminated river reaches had elevated whole-body trace element concentrations. However, direct comparisons of contamination using a single, common species among stations were limited because few species were distributed throughout the study reaches. Comparisons of contamination at taxomic levels higher than species were complicated by element-specific differences in bioaccumulation among taxa. These differences appeared to be governed by biological and hydrogeochemical factors. The variation in element concentrations among species of the caddisfly Hydropsyche was slightly greater than within individual species. If this genus is representative of others, comparisons of contamination within genera may be a practical alternative for biomonitoring studies when single species are not available.

Bats and Water: Anthropogenic Alterations Threaten Global Bat Populations

“…Other species included in the study had high arsenic levels as well as other contaminants (copper, lead, barium, manganese, and zinc) (King et al 2001). Bats and other terrestrial vertebrates can also be exposed to high levels of contaminants by ingesting aquatic emergent insects living in toxic streams and High levels of bioaccumulated cadmium and zinc are known to occur as far as 381 km downstream from the pollution source, whereas lead was found to be transferred from sediments to chironomids (midges) only as far as 40 km downstream (Cain et al 1992). Thus, large stretches of streams and rivers far from the point source of contamination pose threats to bats and other aquatic and terrestrial wildlife.…”

The Cost of Tolerance: Sensitivity of Stream Benthic Communities to Uv-B and Metals

“…Excluding this group, we identified community characteristics that were likely influenced by metal exposure history. Caddisflies, organisms considered relatively tolerant of heavy metals (Cain et al 1992), made up a larger proportion of the non-dipteran macroinvertebrate community from the metal-polluted site (73%) compared with the reference site (52%; P ¼ 0.008). Likewise, mayflies, organisms considered sensitive to heavy metals , were 13% more abundant at the reference site compared with the metal polluted site (P ¼ 0.04).…”

The effects of bauxite/alumina waste on the composition of the macroinvertebrate community of the Rio Cobre, a major river in Jamaica

“…Because benthic macroinvertebrates are continuously exposed to conditions they serve to integrate the effects of contaminants over time and provide a measure of water quality. Macroinvertebrates are frequently used as bioindicators of pollution in freshwaters for a number of other reasons, (Cain et al 1992). These include the fact that they are largely sedentary organisms whose presence or absence is often a good indication of conditions in the area.…”