Functions of Ecosystems: Stream Metabolism as an efficient and effective means to gage the health and understand the interworking of urban streams in a watershed of Rock Island, IL

Stream metabolism is a critical functional measure of stream health that integrates physical parameters like slope and discharge, with ecosystem functions like photosynthesis and respiration. Stream metabolism is widely studied; however, urban stream metabolism remains poorly understood. Stream metabolism was measured for five streams ranging from 1st to 5th orders from October 11th to October 18th 2017 and four streams ranging from 1st to 4th order from October 22nd to 25th 2017 located within an approximately 9.3 square kilometer watershed of Rock Island, IL that has an urban to suburban type of development. These measurements were carried out using calibrated HACH water quality multiprobes measuring continuous temperature and oxygen concentrations over five days for the earlier data collection and three days for the later data collection at thirty-minute intervals. Metabolism was estimated using a Monte Carlo Markov Chain approach that took into account irradiance and gas-transfer velocity to estimate the 24 hr average and time stepped community respiration, gross primary production, and the total mass flux of O2 by gas exchange. This data was then compared with previously collected physical and chemical data from each site. All sites were characterized by relatively low rates of gross primary production that were far less than community respiration, a pattern that indicates a reliance on energy input from outside the stream rather than in stream photosynthesis. Variation in respiration and photosynthesis were poorly explained by the existing water quality data for the sites (range of R2 data). However, two of the sites experienced transient drops in dissolved oxygen to at or near 0 mg/l. When those two sites are removed from the analysis, total Phosphate concentration (mg/l) and fecal coliform where both negatively related to integrated community respiration (R2 value of .4965 and .53 respectively). These transient drops in oxygen remain unexplained but show the importance of continuous monitoring for ...