Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität zu Bonn, 1997.

In order to gain better understanding of climate change effects on ecosystems, it is necessary to study the response of different species to predicted climate change. Dragonflies are, due to their ecology, a suitable organism group for conducting such studies. In this pilot study we examined the response in growth- and mortality rate to increased ambient temperatures in an experimental set-up of three temperature levels (20°C, 22°C och 24°C) in larvae of three species from the Aeshnidae family (Aeshna grandis, Aeshna cyanea and Anax imperator). A. imperator were, due to insufficient number of collected specimens, excluded in the 22°C temperature regime. The studied species are reproducing in Sweden, but A. grandis and A. cyanea are native, whereas A. imperator is considered newly established since it was first discovered in Sweden in the early 2000’s. Our results show that A. grandis and A. cyanea reacted positively to an increased ambient temperature, in terms of growth rates. However, the response to increased temperatures differed between the two species as A. grandis showed both higher growth- and mortality rate, compared to A. cyanea. Thus, we assume that both species are likely to benefit from the ongoing climate change, but that interactions between them may change. Further studies are required to elucidate how the two species will be affected in presence of newly established species, such as A. imperator. Although, based on our results, the competitiveness of both native species might increase with rising temperatures - which should be considered in future conservation planning.