Food webs in lakes : seasonal dynamics and the impact of climate variability

Abstract

As a result of increased green-house gases, global surface temperatures increased strongly during the twentieth century and will most likely increase between 1.4 5.8°C within the twenty-first century(Houghton et al. 2001). Early signs of climaterelated gradual changes in lake ecosystems have been reported (Schindler et al. 1990; Magnuson et al. 2000; Straile 2002; Livingstone 2003; Straile et al. 2003) and further changes are expected to come. Besides the increase in temperature, the increase in greenhouse gases per se (e.g. Urabe et al. 2003; Beardall and Raven 2004) as well as other associated phenomena, for example, increase in UV-B radiation (e.g. Schindler et al. 1996; Williamson et al. 2002), and their interactions will affect organisms in lake ecosystems (Williamson et al. 2002; Beardall and Raven 2004). This chapter can obviously not cover in detail these issues in global change research; instead the emphasis will be on possible food-web effects of temperature increase and variability. For recent reviews on various effects of climate forcing on lakes see (Carpenter et al. 1992; Schindler 1997; Gerten and Adrian 2002a; Straile et al. 2003).