Distribution and production of submerged macrophytes in Tipper Grund (Ringkoebing Fjord, Denmark), and the impact of waterfowl grazing.
The aquatic plants in this study were Ruppia spp. which occur at shallow depths, Chara spp. at intermediate depths and Potamogeton pectinatus, Myriophyllum spicatum and Ranunculus baudauti at the greatest depth. Annual waterfowl consumption was estimated to be about 30% of the annual macrophyte production on a dry wt. basis or nearly half the maximum biomass. However, the direct effect of grazing on aquatic vegetation could not be detected in the comparison with ungrazed controls. Most grazing occurred during autumn when the plants were dying off. From summary.