Caddisfly larvae as bioindicators of metal pollution in aquatic systems
Monitoring of water and sediments by metal analysis is not sufficient because of fluctuating metal concentrations in the water and delayed responses of sediments. It also provides little information about metal bioavailability in aquatic ecosystems. Therefore, aquatic organisms (e.g. aquatic insects) are commonly used for biomonitoring the actual metal load of aquatic biota. Caddisfly larvae satisfy some important criteria established for bioindicators, thus being valuable biomonitoring organisms of metal contamination in freshwater ecosytems:
· wide distribution: The animals are ubiquitous across a broad range of aquatic habitat types.
· high abundance: In many waters caddisfly larvae often occur in large quantities, even at contaminated sites
· easy to collect: Caddisfly larvae can be collected by simple, inexpensive methods.
· low mobility: Caddisfly larvae are benthic animals. Being continously exposed to contaminants, they represent the local conditions of pollution.
· high sensitivity: Caddisfly larvae reflect metal contamination at pollution levels hardly detectable by analysis of sediment samples.
Furthermore, an Austrian-Canadian cooperation between our working group and the Canadian Forest Service (Great Lakes Forestry Centre, Sault Ste. Marie, Ontario, Canada) has been established in 2000. This collaborative project was aimed to study the effects of forest managment activities on the metal remobilization in the Turkey Lakes Watershed by using aquatic insect larvae as a sensitive biomonitoring tool.
The aim of this project coordinated by the Institute of Limnology of the Austrian Academy of Science (Mondsee) was the investigation of the effects of metal-contaminated industrial effluents on the ecosystem of a large lake (Traunsee) in Upper Austria. The team members from the Institute of Zoology and Limnology-Department of Ecophysiology contributed to the project by investigating metal contamination in fish, mussels and benthic invertebrates and various biochemical indicators of stress in the fish.
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