The Influence of Land Use Changes on Aquatic Ecosystem Health and Water Quality

Abstract

Land-use change resulting from human activities has been identified as one of the leading causes of hydrological disturbance and ecological degradation to aquatic ecosystems within riverine catchments throughout the world. The research has tested structural relationships between upstream landscape characteristics and downstream aquatic ecosystem integrity at the catchment-scale using a dataset compiled from forty-five sample sub-basins over a three-year time frame. The study constructed physicochemical water quality indices, macroinvertebrate multi-metric scores, and high-resolution land-cover data based on satellite imagery and used this data to test spatial and temporal response curves. Empirical data found strong tipping point responses, indicating macroinvertebrate community structure undergoes a steep decline in structural diversity (indicated by a sharp decline in EPT taxa richness) at catchment-scale sub-basin urbanization rates of 12.5%. In contrast, agricultural expansion had a strong negative correlation with persistently elevated levels of total dissolved solids and reactive macronutrients. Predictive linear mixed-effects models have suggested that riparian vegetated buffers, through their physical configuration across the landscape, appear to provide an especially important spatial filter preventing catchment-scale agricultural intensification from being translated into physical degradation in-stream. Our study provides concrete quantitative measures of these relationships that can aid landscape planners interested in a landscape pattern approach to maintaining ecological health even within heavily disturbed landscapes.