(1) The submerged macrophytes of the shallow, oligohaline Tipper Grund were mapped. Total biomass increased with depth and with the content of organic matter, N, C, silt and clay in the sediment. The different species separate along the depth gradient. Ruppia spp. occur at shallow depth. Chara spp. at intermediate depth and Potamogeton pectinatus, Myriophyllum spicatum and Ranunculus baudauti at greater depth. (2) All macrophyte species showed a unimodal peak of biomass during the summer. Angiosperms with heavy epiphytic load withered 1-2 months earlier than did angiosperms without epiphytes. (3) Annual waterfowl plant consumption in the entire area (1400 ha) was estimated as 283 t ash-free dry wt, representing about 30% (15-60%) of the annual macrophyte production (968 t ash-free dry wt), or nearly half the maximum biomass. In spite of this high percentage, the direct effect of grazing could not be detected by comparison between a normal sampling plot and a plot protected against waterfowl grazing. Most grazing occurred during autumn, when the plants were dying off, and little occurred during the growing season.
|Journal||Journal of Applied Ecology|
|Publication status||Published - 1980|