Periphyton Response Across a Land-Use Gradient in the Lake Simcoe Watershed

Session: 56. - Science for a Healthy Lake Simcoe

Sarah MacKay, UOIT, [email protected]
Andrea Kirkwood, University of Ontario Institute of Technology, [email protected]

Abstract

It has been estimated that 31% of phosphorus loading in the Lake Simcoe watershed (LSW) originates from urban stormwater runoff. Cosmetic fertilizer use on lawns and gardens may be a potential contributor. As part of a larger study investigating the non-agricultural sources of nutrients in the LSW, we conducted substrate-colonization experiments to assess periphyton response to nutrients and water quality conditions in tributaries of the LSW. Using GIS and Human Activity Gradients, 14 tributary sites were selected representing a land-use gradient of reference-agriculture-urban. Five landscape pavers were deployed at each site and collected after 21 days to measure periphyton growth and community structure during spring, summer, and fall. Chloride was significantly higher at urban sites in all seasons. Phosphorus (TP and TDP) and nitrogen (TN) concentrations were variable across sites and seasons. Chlorophyll a showed variability at agriculture and urban sites in all seasons. Interestingly, a high proportion (75-84%) of colonial blue-green algae were present on pavers from all sites during what was deemed a drought summer. Periphyton from spring and fall are currently being analyzed to determine seasonal community shifts as they relate to site conditions.

1. Keyword
algae

2. Keyword
Lake Simcoe

3. Keyword
nutrients

4. Additional Keyword
land-use

5. Additional Keyword
periphyton