Water Ecological Assessment of Lake Sulzkar (National Park Gesäuse)

Ten years after the initial examination, chemical-physical parameters were measured in the Sulzkar Sea, phyto and zooplankton densities were collected, the sediment in the litoral examined and the lake fished with multi-mesh nets and an electric aggregate. The ecological condition has improved slightly. A restoration of the natural situation is only possible if the Elcorices (Phoxinus phoxinus) are removed by draining the lake. The lock-out of the grazing cattle has led to an improvement in the trophic situation in Lake Sulzkar. Total phosphorus and nitrate concentrations had decreased slightly, but repeated studies would be necessary to confirm these findings. By turning off the artificial feed, the predatory salmonids have disappeared from the lake. The Elritzen (Phoxinus phoxinus) could be observed hunting in open water and have caused the 2003 dominant crustacean species Daphnia longispina to disappear. In contrast to the initial study, the standing stock of the plankton, with almost completely altered species spectrum, was this time strongly shifted in favour of the Algerian primary producers (relative phytoplankton: Zooplankton 6:1, decreasing vertically to 2:1). In the autumn of 2003, the mostly algivore primary consumers reached nearly the double biomass of the phytoplankton. The shore zone (aquatic and terrestrial) was present to a small extent in 2013 and only locally fecally contaminated. A restoration of the natural situation appears only possible if the Elritzen are removed from the lake. Only then can large crustacean species and amphibians resurface in the lake. With the help of a pipeline, the Sulzkar Sea could be drained within a few days. It is not possible to eliminate the fish stock with multi-mesh nets or with an electric unit. Ten years after the initial examination, chemical-physical parameters were measured in the Sulzkar Sea, phyto and zooplankton densities were collected, the sediment in the litoral examined and the lake fished with multi-mesh nets and an electric aggregate. The ecological condition has improved slightly. A restoration of the natural situation is only possible if the Elcorices (Phoxinus phoxinus) are removed by draining the lake. The lock-out of the grazing cattle has led to an improvement in the trophic situation in Lake Sulzkar. Total phosphorus and nitrate concentrations had decreased slightly, but repeated studies would be necessary to confirm these findings. By turning off the artificial feed, the predatory salmonids have disappeared from the lake. The Elritzen (Phoxinus phoxinus) could be observed hunting in open water and have caused the 2003 dominant crustacean species Daphnia longispina to disappear. In contrast to the initial study, the standing stock of the plankton, with almost completely altered species spectrum, was this time strongly shifted in favour of the Algerian primary producers (relative phytoplankton: Zooplankton 6:1, decreasing vertically to 2: 1). In the autumn of 2003, the mostly algivore primary consumers reached nearly the double biomass of the phytoplankton. The shore zone (aquatic and terrestrial) was present to a small extent in 2013 and only locally fecally contaminated. A restoration of the natural situation appears only possible if the Elritzen are removed from the lake. Only then can large crustacean species and amphibians resurface in the lake. With the help of a pipeline, the Sulzkar Sea could be drained within a few days. It is not possible to eliminate the fish stock with multi-mesh nets or with an electric unit.