A validated bioenergetics model for ruffe Gymnocephalus cernuus and its application to a northern lake

A bioenergetics model was constructed for ruffe Gymnocephalus cernuus , and the model was used to estimate the food consumption of a native G. cernuus stock in Pyhäjärvi, a large mesotrophic lake in south-west Finland. The parameters for the bioenergetics model were determined through laboratory experiments conducted at several temperatures between 5 and 22° C for different sized G. cernuus (from 6 to 27 g). The model was verified and validated with independent laboratory growth experiments. The validated model was applied to field data from Pyhäjärvi to estimate the food consumption of G. cernuus and its effects on the zoobenthos community during the years 2002–2004. The total annual food consumption of the G. cernuus stock ranged from 11·6 to 15·7 g m^?2 (wet mass). Chironomidae was the most abundant prey, 81% of the total consumption. The annual total production of zoobenthos in Pyhäjärvi was 15·2 g m^?2 (wet mass). Therefore, it can be concluded that G. cernuus stock is likely to exert a significant influence on the zoobenthos community in this lake, indicating a potential role of G. cernuus as an influential invasive species in many freshwater ecosystems in Europe and North America.