Zooplankton community, size distribution and production in the Toronto and Region Area of Concern

Session: 05. - Within Reach: The Path to De-listing Toronto and Region as a Great Lakes Area of Concern

Robin Rozon, Fisheries & Oceans Canada, [email protected]
Kelly Bowen, Fisheries and Oceans Canada, [email protected]
Warren Currie, Fisheries and Oceans Canada, [email protected]

Abstract

Toronto Harbour, adjacent to Canada’s largest urban center, has had few plankton studies despite its designation as an Area of Concern. Surveys of plankton and water properties for the Toronto Region were undertaken by Fisheries and Oceans Canada (DFO) in September 2013 and monthly from May to October in 2016 to reinforce earlier sporadic sampling in the area. Sampling covered five distinct areas: the inner harbour, the outer harbour, Humber Bay, Ashbridges Bay and offshore. The inner and outer harbours were significantly elevated in chlorophyll, phytoplankton and bacterial production rates. The inner harbour biomass and production were dominated by Bosmina sp. as compared to the other stations, where biomass and production were dominated by Daphnia sp. and cyclopoid copepods. Daphnia sp. mean length was significantly different within and outside the inner harbour. Additionally, species of Daphnia and calanoid copepods showed distinct habitat preferences, with D. retrocurva virtually absent outside of the inner harbour in 2016. We will outline how these results support a food-web approach to determine disruptions in the pelagic food web in order to assess the Beneficial Use Impairment (BUI) #13: Degradation of phytoplankton and zooplankton populations.

1. Keyword
zooplankton

2. Keyword
monitoring

4. Additional Keyword
Food-web approach