US EPA

8197951 

Journal Article 

Applicability of the food web manipulation in the restoration programme of a hypertrophic stratified lake: Model studies for Lake Haussee (Feldberg, GDR) 

Kasprzak, P; Benndorf, J; Koschel, R; Recknagel, F 

1988 

1 

Limnologica
ISSN: 0075-9511
EISSN: 1873-5851 

19 

1 

87-95 

English 

BCI:BCI198987025279 

Lake Haussee (Feldberg, GDR) is a highly eutrophic lake due to external nutrient load from a municipal waste-water treatment. In 1980 the effluent was interrupted, but the remained in the state of hypertrophy because of the great amount of accumulated nutrients and high internal load. Investigations about hydrology and chemistry on the one side and the structure of the food-web on the other side showed, that the self-purification potential is rather low. Therefore we investigated the effect of food-web manipulation by means of scenario studies using the ecological lake model SALMO. It was shown that decreased zooplankton mortality leads to drastic reduction of phytoplankton biomass. The second part of the spring maximum is nearly suppressed and also the concentration throughout the rest of the year is 50-75% lower. There are indications for interactions between food-web manipulation and calcite precipitation, another important loss-factor of phytoplankton in hard-water lakes. Pelagic calcite precipitation with its connected decreases of primary production works most efficient in mesotrophic lakes. Because food-web manipulation leads also to limitation of phytoplankton growth a stimulation of calcite precipitation can be assumed.