Interannual synchronous dynamics in north temperate lakes in Wisconsin, USA
One way of assessing the potential influence of climate change on lakes is to take advantage of the fact that neighbouring lakes are exposed to nearly identical climatic variations. Limnological features most directly influenced by climatic processes would be expected to vary synchronously across neighbouring lakes. By examining patterns of synchronous behaviour, i.e. temporal coherence, across lakes, we can identify the extent to which we would expect various features oflakes to shift regionally in response to climatic change. We assessed the degree to which 6llimnological parameters varied synchronously across eleven north temperate lakes, seven in northern Wisconsin USA and four in southern Wisconsin, over a 13-year period. Physical variables such as dates of ice-on and ice-off, water level, and water temperature, varied synchronously across years. Chemical variables were in general less coherent than physical variables; however, selected chemical variables, such as major ions, were highly coherent. The coherence of major ion data is likely due to similar responses to a several-year drought that occurred midway through the period. Biological data exhibited little or no coherence. Lake pairs containing at least one dystrophic lake did not vary synchronously, whereas lake pairs containing two clearwater lakes showed moderate levels of coherence. Our results suggest that regional generalizations for effects of climate change on lakes should be possible for many physical and some chemical features of clearwater lakes, but regional generalizations for dystrophic lakes or biological features will be difficult.
Kluwer Academic Publishers