Linking nutrient limitation and water chemistry in upland lakes to catchment characteristics

The relationship between catchment characteristics and lake water chemistry, phytoplankton and periphyton biomass, and phytoplankton and periphyton nutrient limitation was investigated for 30 upland lakes in the U.K. These catchment characteristics included the proportion of different land cover categories in the catchment and some hydrological information. Multiple regression models could predict alkalinity, pH, total dissolved phosphorus, dissolved inorganic nitrogen, dissolved organic nitrogen, dissolved organic carbon and phytoplankton chlorophyll a from the proportional contribution of between two and six land cover categories within the catchment and explain between 42 and 73% of the variance. Phosphorus limitation was positively linked to the proportion of shrub-heath and bracken in the catchment, and negatively linked to the proportion of pasture. Nitrogen limitation was positively linked to the proportion of marsh and rough grass, deciduous and mixed woodland, and negatively linked to the proportion of rough pasture, shrub heath and bare ground in the catchment. Nitrogen limitation decreased and phosphorus limitation increased with catchment slope, although the correlation between land cover classes and slope was not significant. The results suggest that map-based data can be used to predict water chemistry and nutrient limitation in upland lakes.