Movement and Assemblage Structure of Small Stream Fish in an Urban Environment: How Interconnected Are Streams and Stormwater Drains?

Urban ecology is a discipline that has emerged in response to the unique changes associated with urbanization. Research on ecosystem impacts is still lacking, particularly on fish populations within urban stormwater drains. Our research goal was to study the assemblage and movement of stream fish over a one year period within an urban stream (Watts Creek), an earthen stormwater drain tributary (Kizell), and the area downstream of their confluence (herein termed Main) in Kanata, Ontario. By comparing fish assemblages and using passive integrated transponder technology we found the assemblage structures of Kizell and Watts were relatively distinct throughout most of the year, there was little variation in the directionality of movements between Kizell and Watts, and some species would reside within Kizell for long periods of time. These findings demonstrated the connectivity between Kizell and Watts, and that stream fish are moving into, residing, and utilizing habitat within Kizell throughout the year (including during the winter). We conclude that earthen stormwater drains can provide habitat that supports fish communities across seasons and are a functional component of urban stream systems.