Water Resources Research Act Program

Details for Project ID 2016AR389B

Does macrograzer activity drive seasonal variations in algal biomass in Ozark streams?

Institute: Arkansas
Year Established: 2016 Start Date: 2016-03-01 End Date: 2017-02-28
Total Federal Funds: $5,000 Total Non-Federal Funds: $10,000

Principal Investigators: Michelle Evans-White

Abstract: Elevated nitrogen (N) and phosphorous (P) in streams can cause nutrient pollution leading to instream and downstream problems of excess algal growth which can constrain the recreational use of streams and reduce stream biodiversity. The United States Environmental Protection Agency (USEPA) provided national nutrient criteria standards, but these do not account for regional variations in nutrient concentrations. A dose- or stressor-response relationship between nutrient levels and stream benthic algae is being developed by Arkansas Department of Environmental Quality (ADEQ) in accordance with Arkansas’ Regulation No. 2 narrative. Unfortunately, the sampling method implemented by ADEQ to examine the relationship between nutrient concentrations and algal biomass does not include assessment of grazer presence or abundance at the same sites where benthic algal biomass is measured. Intense grazing pressure by benthic algivores (i.e., grazers) may decrease the slope of the relationship between nutrients and algae, thus dampening the magnitude of the effect of nutrient enrichment in streams. Studying seasonal variations in algal density associated with macrograzer activity is important in understanding the dose-response relationship between nutrients and benthic algal biomass and thus should be important in determining regional nutrient criteria for the Ozark Highland Ecoregion. Stonerollers (Campostoma spp.) are minnows that occur in high abundances in Ozark streams, and possess a sub-terminal mouth that makes them well-equipped grazers. Campostoma spp. grazing can be an important determining factor on algal biomass and community composition and could explain variation in algal biomass across seasons and sites in Ozark streams with varying nutrient concentrations. The proposed study examining the seasonality of the Campostoma spp. grazing effect can help the state understand how and why seasonality may result in variation in the relationship between nutrients and algal biomass.