Climate sensitivity of Oak Mere: a low altitude acid lake

1. Hydrologically open lakes in temperate regions are not considered as sensitive to climate change as closed-basin lakes in semiarid regions. 2. Oak Mere is an acid lake in lowland UK. It has no surface inflow or outflow but is connected to the regional groundwater. It is a high landscape, hydrologically open Lake. 3. This paper describes how Oak Mere responded to drought with rapid and substantial changes in acidity and nutrients. Decreases in pH and catchment-derived nutrients appear to be a response to the relative amount of catchment-derived minerals compared with those received in direct precipitation. 4. The extreme sensitivity of the site appears to be due to negligible groundwater inputs, low buffering capacity and a short retention time. 5. The paper demonstrates that high landscape sites may represent the most sensitive hydrologically open lakes to climate change. This not only has consequences for acidification and eutrophication studies. These sites may also be considered valuable in that they potentially offer an important new archive for palaeoclimate studies, with a sensitivity previously considered unavailable in low altitude temperate regions.