A Novel Reproductive Response of a Planktonic Herbivore to Temperature Stress

Global climate change, natural disasters and anthropogenic modifications of waterways may all lead to changing water temperature patterns in aquatic systems. We assessed the effects of different water temperatures on the reproductive rates of Daphnia pulex, a common primary consumer in aquatic ecosystems. Life table experiments were conducted using animals acclimatized to 10 ¡C and 20 ¡C water temperatures. Our findings at intermediate temperatures support findings from previous studies: Daphnia tend to show high reproductive rates at temperatures around 20 ¡C. (Bottrell, 1975; Lennon et al., 2001). We also observed unexpectedly high reproductive rates for 10 ¡C acclimatized clones in 30 ¡C treatments. These findings suggest the presence of a previously unrecognized coping mechanism present in this species for dealing with rapid, large temperature fluctuations.