Relationships Between Land Use and Stream Macroinvertebrate Biotic Integrity in Central Ohio, USA

Land use is known to be an important factor in the composition and function of adjacent freshwater lotic ecosystems. However, the relative effects of land use type, extent, intensity, and proximity on aquatic ecosystem quality are not fully understood. We evaluate these questions in low-order streams within 30 watersheds in developed, agricultural, and less developed landscapes of central Ohio, USA. We assess the relationships of land use cover percentage and spatial scale with stream macroinvertebrate community diversity and biotic integrity. We also investigate the importance of impervious cover and subsurface tile drainage within each watershed and Active River Area (ARA). We find that the percentage of coverage of developed land at the watershed scale is the strongest predictor of stream macroinvertebrate community diversity and integrity. High-intensity development is a stronger negative correlate than low-intensity development or agriculture. There is a significant decline in stream macroinvertebrate diversity and biotic integrity at the watershed and ARA scales when undeveloped land coverage falls below 20–30%. We do not find a significant relationship between stream macroinvertebrate metrics and land use at the 1 km2 scale or in comparison with any instream habitat attributes except sinuosity. Impervious cover has a significant negative relationship with both macroinvertebrate taxon richness and biotic integrity at the watershed and ARA scales. However, subsurface tile-drained land does not have a significant relationship with the stream macroinvertebrate community at any scale. We conclude that impervious land cover at the watershed and ARA scales is a critical factor for the biotic integrity of small streams in this region. Collectively, our conclusions provide evidence to support practices of ecologically sensitive land use planning.