Assessing the influence of water and substratum quality on benthic macroinvertebrate communities in a metal‐polluted stream: an experimental approach

Abstract

SUMMARY 1. Field and laboratory experiments were conducted to assess the relative influence of water quality and substratum quality on benthic macroinvertebrate communities in the Animas River, a metal‐polluted stream in south‐western Colorado (U.S.A.). 2. A community‐level in situ toxicity test measured direct effects of Animas River water on benthic invertebrates collected from a reference stream (Elk Creek). The effects of metal‐contaminated biofilm were examined by comparing macroinvertebrate colonisation of clean and contaminated substrata placed in Elk Creek. A feeding experiment with the mayfly Baetis tricaudatus Dodds (Ephemeroptera: Baetidae) examined metal bioaccumulation and effects of metal‐contaminated biofilm on growth and survival. 3. Animas River water was acutely toxic to most taxa, with greatest effects observed on mayflies (Heptageniidae, Ephemerellidae) and stoneflies (Taeniopterygidae and Capniidae). 4. Although Animas River biofilm was characterised by high concentrations of metals and low algal biomass, most taxa colonised substratum from the reference stream and the Animas River equally. The exceptions were Ephemerellidae, Taeniopterygidae and Simuliidae, which were less abundant on Animas River substratum. Mayflies grazing Animas River biofilm accumulated significantly more metals and showed reduced growth compared with organisms feeding on Elk Creek biofilm. 5. Results of our experiments demonstrated that effects of heavy metals on benthic community structure in the Animas River were complex, and that responses to metals in water and contaminated substratum were species‐specific. Predicting recovery of benthic communities following remediation requires an understanding of these species‐specific responses.

Seasonal Dynamics of Shallow-Hyporheic-Zone Microbial Community Structure along a Heavy-Metal Contamination Gradient

“…Indeed, only the two most highly contaminated sites (SB and GC) had detectable soluble concentrations of As, Cd, Cu, and Zn, and none of the sites had detectable levels of soluble Pb in the pore water. Sediment-associated metals appear to be bioavailable (17), and previous work has described diurnal variations in dissolvedmetal levels in the upper Clark Fork River (9), indicating an equilibrium between sorbed and aqueous-phase metals in this system. Thus, the use of a contamination index based on total metals associated with sediments should be a valid estimate of the magnitude of contamination to which hyporheic microbial communities are exposed.…”

Metal‐induced shifts in benthic macroinvertebrate community composition in Andean high altitude streams

“…Indirect effects include smothering of the streambed substrate by metal precipitates, reducing the habitat availability for stream fauna, decreasing food quality, and modifying interactions between functional feeding groups [11][12][13]. In addition, it has been reported that related species from elevated temperate streams (2,500 meters above sea level [masl]) are more sensitive to metals than those from lowland streams [10,14].…”

Eukaryotic Community Distribution and Its Relationship to Water Physicochemical Parameters in an Extreme Acidic Environment, Río Tinto (Southwestern Spain)

“…It has been also proposed that metal hydroxide deposition could change the physicochemical conditions of surfaces, resulting in a reduction of epiphytic growth on rocks (8). However, what makes Río Tinto a unique acidic extreme environment is that eukaryotic organisms are the principal contributors of biomass in the river, over 65% of the total biomass, as well as the unexpected degree of eukaryotic diversity found in its waters (1,21,28).…”