Effects of extreme water levels on fish communities of the Upper St. Lawrence River

Session: 30. - Ecosystem Impacts of the Lake Ontario-St Lawrence River Flood of 2017

Matthew Windle, St. Lawrence River Inst., [email protected]
Kate Schwartz, St. Lawrence River Institute, [email protected]
Tyler Sunday, Mohawk Council of Akwesasne, [email protected]
F. Lickers, Mohawk Council of Akwesasne, [email protected]
El-Amine Mimouni, St. Lawrence River Institute for Environmental Sciences, [email protected]

Abstract

The effects of record-high water levels on the structure and habitat quality of nearshore aquatic communities of the Upper St. Lawrence River were investigated.  We compared fish assemblages and habitat characteristics at shoreline sites from Cornwall to Brockville that were sampled from May to August in 2017 and 2016.  Water quality analysis found that nutrients (total phosphorous and nitrates) were not significantly different between years, but were consistently higher early in the survey period and at specific sites, likely as a result of proximity to nearby tributaries.  Macrophyte abundance and cover was significantly greater in 2017 at the majority of sites.  Overall fish abundance was significantly higher in 2017 for some sites, with some exceptions.  Fish diversity did not differ significantly between years.  The implications for management, remedial activities, and predictive modelling are discussed.  

1. Keyword
St. Lawrence River

2. Keyword
fish populations

3. Keyword
water level fluctuations