Relationships between algal biomass and diversity with stream size and adjacent land use

Abstract

Land use adjacent to waterways, such as development or agriculture, alters hydrological patterns leading to increases in runoff and nutrient input. Forests and wetlands, as natural land cover types, reduce water movement and allow infiltration into soil. We measured algal biomass and diversity in order to quantify the influence neighboring land cover types have on streams in Northeastern Indiana. In the study area, cultivated crops were the dominant land cover type, with open development and deciduous forest following. Emergent wetland area had the greatest influence on algal biomass, with increases in wetland area decreasing biomass. However, open development, low intensity development, grassland, shrub, and forested wetlands added to increases in biomass. Conversely, forested wetlands reduced algal richness, while open development and pastures increased richness. Because open development (i.e. dominated by turf grass, lawns, parks, golf courses) was the second most common land cover type and positively influenced both algal biomass and richness, management of those properties will likely have direct impact on nutrient flow into streams. Additionally, adding functional wetlands dominated by emergent herbaceous plants will directly impact future algal biomass.