Trophic relationships of benthic mountain stream organisms based on C and N isotope composition

Samples of benthic organisms (insect larvae, molluscs, crustaceans, etc.), growths from boulders, fine particulate organic matter, algae, mosses and water were taken from mountain streams in areas built by crystalline, Mesozoic carbonates, neovolcanics and flysch. Samples of biological materials were preserved with 96% alcohol p.a. In the area built of crystalline rocks, samples were taken from 16 localities, mostly in the High Tatras, and partly in the Low Tatras. As the whole set of samples has not been processed yet, in this paperthe authors will limit themselves to the presentation of the results obtained from the samples taken in this area. Mountain streams represent a high-energy environment, with dynamic mass exchange. Identifying trophic relationships based on the isotopic composition of benthic organisms and their primary producers in such an environment is a relatively complicated task. From the results so far, it is clear that within one locality we have to deal with trophic chains based on primary producers of different origins, their intermingling. The situation can also be complicated by anthropogenic activity, in this case logging in wooded areas cause the flushing of larger amounts of organic matter of terrestrial origin. (authors)