The study of lakes has attracted many scientists over the years and those who specialise in attempting to understand the complex workings of the entire lake ecosystem are now known as limnologists (Wetzel 1983). Most of them deal specifically with what is happening in lakes today, but in recent years some have begun to appreciate that the present character of the lakes they study is the result of a Jong history. It is now realised that to fully understand the functioning of lakes and how to manage them for the future we have to understand their past.