Stephen Maberly, Centre for Ecology & Hydrology
Some of the world’s longest and most comprehensive long-term monitoring records exist for the lakes in the English Lake District. This provides an unparalleled record of the responses of lakes and their wildlife to environmental change that extend back for over 65 years at four lake basins. The work was started by the Freshwater Biological Association in the 1940s, but has been undertaken by CEH since the late 1980s. Consistent methods, or closely-validated changes, have been used and new complementary methods to assess biodiversity have been introduced. The monitoring has increased understanding of the functioning of lakes, provided data to validate models and allowed changes in response to natural variation to be detected. Importantly, because a range of physical, chemical and biological variables are measured, the causes of any changes can begin to be attributed and this is supported by other types of study such as laboratory experiments or comparisons across many lakes. This ‘systems approach’ allows responses to multiple stressors to begin to be untangled. The talk will give case-examples of how lakes are affected by single or multiple environmental stressors such as natural variation in the weather, climate change, nutrient enrichment, soil erosion in the catchment and invasion of non-native species. It will emphasise the importance of fundamental knowledge, for example on mechanisms controlling species distribution, and the use of models to test ideas generated by observation and to forecast possible responses in the future.