Windermere is England's largest natural lake and one of the best studied in the world with detailed records extending back over 70 years. A marked deterioration in water quality has been observed in the last 10 to 15 years despite continued removal of a key nutrient, phosphorus, at the two adjacent wastewater treatment works. For example in recent years, summer algal blooms have increased, concentrations of oxygen at depth have decreased and the numbers of the rare and protected fish, the Arctic charr, have declined dramatically. These changes have coincided with the population expansion of a lower-latitude, non-indigenous species, the roach.

See Prof. Stephen Maberly’s background presentation here.
In this project we will use a range of methods to test the hypotheses that the roach expansion is a result of the documented warmer waters in Windermere and that the expansion has triggered a 'trophic cascade' leading to greater predation on the zooplankton, which in turn has reduced the control on algal abundance by their grazer. We will also test whether the decline in Arctic charr numbers results from competition with roach, since both feed on the zooplankton and will also consider trophic-interactions with the top-predator in the lake, the pike.
The results will be highly relevant to the management of lakes since, if our hypotheses are correct, nutrient removal will need to be even more stringent in the face of climate change and disruption of food-chains caused by invasion of non-indigenous species.