Impact of biofilms on dissolved oxygen sensor accuracy drift

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Availability of dissolved oxygen (DO) is a key component of aquatic ecosystem health that is indicative of several key ecosystem services such as fisheries and nutrient retention. Accurate measurement of DO is thus a critical task for aquatic monitoring and research activities that drive management of these vital ecosystems. Amirix Systems Inc., a Canadian company with a 30 year history of innovation in monitoring of aquatic systems, is currently developing a technology for a miniature, in situ, DO logger. This logger will revolutionize continuous DO monitoring by enabling unique applications not currently supported by the much larger, foreign made loggers currently available. New applications will include continuous measurement of DO in mesocosm and microcosms and in sediments as well as enhancing monitoring efficiency and effectiveness in very small streams and remote locations. A key limitation with in situ, continuous monitoring of DO in aquatic ecosystems is the loss of accuracy/drift as a result of biofilm development on the logger sensor. Amirix thus needs validation of the accuracy of their product through in-situ testing in environments with varying but controlled levels of nutrients and hence biofouling rates. The purpose of the proposed research project is evaluate the effect of biofilm development on the new DO sensor through a controlled mesocosm study to be conducted at Western's TRESSES (Thames River Experimental Stream Systems for Ecosystem Studies) research facility located in London, Ontario. This study will expose the Amirix developed sensor to realistic stream environments comprised of local stream ecological under controlled nutrient concentrations (enriched vs background) and measure the rate and magnitude of sensor drift associated with biofilm development. Results of this experiment will provide the performance validation data Amirix requires to improve and market their product. Marketing of this product will enhance Amirix's profile and competitiveness in the international market and will provide a much needed tool for improving aquatic research and monitoring leading to more effective management of aquatic ecosystems.