Spatial patterns of productivity and stable isotope ratios of C and N in Great Lakes tributaries

Session: 34. - Aquatic Habitat Evaluation and Assessment

Michael McKenzie, Trent University, [email protected]
Nicholas Jones, Trent University, OMNRF, [email protected]

Abstract

Thousands of sport fish migrate yearly out of the Great Lakes and into the surrounding rivers to spawn transporting large quantities of nutrients in the form of eggs and excrement. Such resource subsidies have been associated with increases in algae and invertebrate abundance, and recruitment in juvenile lake fish.  Research is required to understand how subsidies influence stream productivity and how this process varies across the landscape including fragmentised streams where fish passage is prevented. Comparisons of stable isotopes in stream fish and benthic invertebrates taken from either side of barriers across 37 Great Lake tributaries can identify organisms that have consumed and benefitted from a subsidy. This information will be partnered with stream productivity estimates and stream characteristics, such as water quality, streambed composition and annual rainfall, to assess where and under which conditions a subsidy is most impactful. This will also allow for the comparison of the relative effects of permeable and semi-permeable barriers, such as lamprey weirs, on resource subsidies. This research seeks to gain further knowledge into a process that may play a significant role in maintaining healthy populations of lake fish and can be used to direct the removal of barriers that fragment the riverscape.

1. Keyword
stable isotopes

2. Keyword
productivity

3. Keyword
tributaries

4. Additional Keyword
Resource Subsidies

5. Additional Keyword
Fragmentation