Seasonal Variation of Standing Crop and Digestibility of CPOM in a Swiss Jura Stream
1983
Bärlocher, Felix
Coarse particulate organic matter (CPOM, diameter > 1 mm) in a hardwater stream in the Swiss Jura reached a maximum of ≈60 g/m² in October and November. It then declined to a low of 4 g/m² in July. The average protein content of stream—collected leaves decreased by ≈50% between November and April. Sixty to ninety percent more protein was extractable at a pH of 11 than at a pH of 8. Digestibility of stream—controlled leaves (characterized by the release of reducing substance and amino acids from ground—up leaves exposed to gut extracts of Gammarus fossarum) also declined from November to April. Average values were considerably lower than those reported for lab—conditioned leaves; however, variability was great. Leaves generally carried active microbial carbohydrases but only rarely active proteases. In November and October, vascular—plant remains filled up to 85% of the guts of Gammarus fossarum. In spring and summer, this value dropped to 23—46%, and fine organic and inorganic particles as well as algae and mosses became more important.
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