Comer, Caitlin, Biology, Bucknell University, 1053 Jewett Road, Skaneateles, NY , 13152, cec039@bucknell.edu; McTammany, Matthew, E, Biology Department, Bucknell University, 1 Dent Drive, Lewisburg, PA, 17837, mmctamma@bucknell.edu.
Rivers and streams exhibit a hierarchical organized system of habitats, ranging across scales from whole river systems to segments or reaches to riffles and pools to microhabitat subsystems. These microhabitat systems, such as patches of distinct substrate types (e.g., detritus, sand-silt, cobbles, fine gravel, and vegetation) within larger habitat units, contribute to natural variability within river ecosystems. While research on the role of nutrients is well documented, especially in lakes, far less research has been conducted on how physical habitat variability shapes algal communities in flowing water systems (ie, streams, rivers). This research targets how substrate complexity and microhabitat conditions influence benthic algal growth, which remains underexplored at fine spatial scales. This study aims to address this gap in the literature by measuring how variation in substrate complexity, and grazer presence influence benthic algal biomass and community composition in Buffalo Creek. Using artificial substrate types designed to mimic natural microhabitats, we measured how varying flow, light and depth conditions influence algal accumulation, as well as how benthic grazers may impact benthic algae abundance. Algal biomass was quantified using chlorophyll a concentrations, and benthic samples were scrubbed from the artificial substrata. Additionally, benthic grazer counts were used to assess potential top-down controls on algal growth. Following this top-down control concept, we expected grazers to reduce algal biomass through top-down interactions. However, we found that increasing microhabitat complexity led to increased algal biomass, as well as increased grazer density. Patterns of algal biomass and benthic grazer density on artificial substrata enhanced our understanding on how algal communities develop and how physical habitat characteristics affect algal dynamics. This research has important implications for how algal community development may be altered by physical habitat structure on the underexplored micro-levels. Findings from this study will contribute to our understanding of algal growth and the role of microhabitats complexity on benthic growth.
Microhabitat Complexity , Benthic Community Structure