Combined effects of chemical and temperature stress on Chironomus riparius populations with differing genetic variability.

Exposure to pollutants under multiple environmental stressors (e.g., climate change and global warming) and the genetic diversity of populations are suspected to have serious impacts on populations and ecosystems but have only rarely been analysed. In the present study, we investigated the effects of the biocide tributyltin (TBT) within a temperature gradient (17, 20 and 23 degrees C) on life history parameters of a genetically diverse (GEN+) and a highly inbred population (GEN-) of the midge Chironomus riparius. While endpoints, mortality and reproduction parameters were considered, the population growth rate as an integrative endpoint was determined. We found severe effects for GEN-, indicating that populations with lower genetic diversity are more endangered by combined stressors such as increasing temperature and chemical pollution compared to genetically diverse populations.