A class exercise for Systems Ecology: Synthesis of stream energetics and testing Allen’s paradox

We report energy stocks and flows, as well as other ecosystem properties, measured in Little Sandy Creek in Upstate New York as part of an intensive class project in a graduate-level Systems Ecology course at the SUNY College of Environmental Science and Forestry. Our study synthesizes information on Little Sandy Creek both as a whole system and through examination of key individual trophic components. We also test Allen’s paradox in Little Sandy Creek – whether there is enough biomass produced by the invertebrate community to support the energetic needs of the fish community. Students collected data in the field over the course of a weekend in September 2012. During the ensuing semester, we synthesized all of these data (often utilizing relatively simple quantitative models) to generate a spatial synthesis populated with trophic levels for a one kilometer reach of stream. We utilized two synthesizing procedures during our trophic flow analysis: first, we sampled organisms along a depth gradient, and modeled trophic levels and size class with depth to give more precise estimates of biomass. Second, we used models for the relation between production and also respiration (energy requirements) and organism size to estimate production and energy use of trophic levels and functional feeding groups. We synthesized and extrapolated upon our data with a numerical model that simulated the stocks and flows in Little Sandy Creek using abiotic forcing functions and functional responses derived from our field measurements. The mean values indicate the benthic macroinvertebrate production (11 kJ m−2 day−1) is insufficient to support the fish energy requirements (13 kJ m−2 day−1) within our uncertainty estimates; given an 80% assimilation efficiency for fish, the macroinvertebrate production is enough to supply only 68% of the fish needs. Our primary hypothesis was supported: students were able to thoroughly collect and organize data from Little Sandy Creek in a single weekend. Further, over the course of a semester, students successfully analyzed their data. We were then able to take that data and build a realistic model of the Little Sandy Creek system. Based on our model outputs, we fail to reject our secondary hypothesis that Allen’s paradox is present in Little Sandy Creek.