DETRITUS AND NUTRIENT DYNAMICS IN THE SHORE ZONE OF LAKES - A REVIEW

The importance of detritus varies greatly among shore zones of lakes, but in a large majority of these regions detrital pathways prevail. As ide from a great spatial and seasonal variability, macrophytes and bot tom sediments appear to be dominant stores of nutrients in these habit ats. Macrophytes hold a central position in nutrient cycling in the sh ore-littoral lake zones. They are the main source of autochthonous det ritus as they prevail in the total biomass of littoral organisms, and they are only rarely available as direct food of consumers. Various pr ocesses and interactions determine the role of macrophytes in nutrient s dynamics. These are: the intensity of nutrient uptake and translocat ion, release of nutrients by healthy plants and from decomposing plant s, exchange of elements between macrophytes and their periphyton, as w ell as interception of seston by macrophyte stands. Particular plant s pecies differ in their time of dying and susceptibility to decompositi on. The changes in decomposing material (size structure of particles a nd nutrient content) mean that detritus in various stages of decomposi tion differs in its role in trophic dynamics of shore-littoral lake zo nes. Several types of shore regions as regards detritus sources and re tention level are discussed.