It is generally expected that climatic signals will be recorded in varved sediments. For example, climatic conditions are linked to the different processes controlling varve thickness (Hardy et al., 1996). However, the climate signal may also be recorded in the diatom assemblages preserved in lake sediments as climatic conditions control the different habitats available for algal growth within the lake and its catchment. Hence, shifts in diatom community composition may reflect changes in microhabitat availability and provide an indirect signal of climate change. Changes in stream and river inflows may also track climatic shifts, and since many diatom taxa are characteristic of different types of flowing waters (for example, running waters are dominated by lotic or rheophilous diatoms) and their deposition in a lake's sedimentary record may provide additional paleoclimatic information (Ludlam et al. 1996).