During the month of February I got the opportunity to once again present my stream ecology research at the ERN Conference in Washington, D.C. This was another great conference where I got the chance to share my research with others, while also visiting the impressive and massive museums and monuments. Title: Stressed Out Streams: The Effects of Agriculture on Stream Nutrient Cycling Abstract: The conversion of forest into agricultural land is known to dramatically affect stream characteristics, including increased water temperature and reductions in organic matter inputs (e.g., woody debris). This study sought to assess the effects of reduced organic matter input on nutrient cycling in streams as mediated by microbial activity. We hypothesized that reductions in woody debris inputs associated with agricultural activity would decrease the cycling of nutrients, such as oxygen and nitrogen. Specifically, we predicted that decreases in organic matter inputs would decrease microbial activity. To test this prediction, we conducted a controlled experiment using streamside flow-through mesocosms within the secondary forest of the Las Cruces Biological Station in Coto Brus, Costa Rica. Treatments consisted of rock substrate or rock substrate with organic material including leaf litter and woody debris, which simulated agricultural and forested stream substrates, respectively. We estimated microbial activity by measuring the amounts of dissolved oxygen (DO) in each stream channel. Our results show that decreases in organic matter decreased microbial activity, but only when microbial activity on both rock and organic substrate is considered. Our findings may also indicate that microbial communities may acclimate to disturbances in a short amount of time and this may be of interest to further work in agriculture and even urbanized streams.
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