Natural versus anthropogenic charge in lakes: The role of the sediment record.

Recent methodological developments permit the quantitative reconstruction of water chemistry variables from microfossil assemblages preserved in lake sediments. These reconstructions can be used to identify the extent and timing of disturbance to lake ecosystems. Combined with appropriate sampling strategies, lake sediments permit water chemistry variables and community rates of change to be estimated at a variety of timescales. Sediments predating major cultural impacts offer the possibility of inferring lake history before anthropogenic interference, and can, therefore, contribute to current debates about timescales of natural variance in lakes, as well as the response of lake communities to natural environmental perturbations. Such an approach has relevance to many contemporary environmental problems, e.g. acidification, eutrophication and climate change.