STREAM BIOFILM FUNCTION IMPACTED BY NUTRIENTS, BUT NOT VELOCITY, ASSOCIATED WITH SIMULATED STORM EVENTS
Storm events temporarily alter stream physiochemistry, including simultaneous altering nutrient concentrations and velocity. We assessed effects of short-term increases in nutrient and velocity on biofilm function by simulating a storm event in artificial streams. A 31-day experiment was conducted in nine outdoor mesocosms in London, Ontario, Canada. Mesocosms were seeded with local biofilm, then received low velocity (0.06m/s) and low phosphorus concentrations (10µg/L) for 17 days, before being assigned to one of three 48-hour treatment levels (1. increased phosphorus (97.3µg/L); 2. increased velocity (0.20m/s); 3. increased phosphorus (97.3 ug/l) and velocity (0.20 m/s)), each replicated in three mesocosms. Benthic metabolism, soluble reactive phosphorus uptake and algal growth (chlorophyll-a) were measured several times before and after the storm event. Decomposition was estimated by measuring the loss of tensile strength in cotton strips over the 31-day experiment. Preliminary results indicate that by the end of the experiment, metabolism and chlorophyll-a were greater in streams that received increased nutrients, compared to just increased velocity. Understanding from our study will help inform river management strategies needed to cope with the effects of increasing storm event severity under predicted land use and climate change scenarios.
Chris Lucas (Primary Presenter/Author,Co-Presenter/Co-Author), Western University & Canadian Rivers Institute, firstname.lastname@example.org;
Nolan J.T. Pearce (Co-Presenter/Co-Author), Western University & Canadian Rivers Institute, email@example.com;
Adam G. Yates (Co-Presenter/Co-Author), Western University & Canadian Rivers Institute, firstname.lastname@example.org;