Seasonal Variation in Phytoplankton Communities of Western and Eastern Lake Ontario

Session: 54. - Food Web Ecology and Dynamics of Lake Ontario: Nearshore ? Pelagic Linkages

Mohiuddin Munawar, Fisheries & Oceans Canada, [email protected]
Heather Niblock, GLLFAS, DFO, [email protected]
Mark Fitzpatrick, Fisheries & Oceans Canada, [email protected]

Abstract

To determine the role of seasonal succession of phytoplankton in Lake Ontario, its abundance, composition and primary productivity were measured approximately monthly from May to November in 2013 and 2017. One nearshore station in the west end and two offshore stations (one each in the east and west) were sampled. Average biomass was highest at the nearshore station (0.9 g m^-3) and lowest at the offshore eastern station (0.4 g m^-3).  Patterns of total biomass were not similar between stations and years, except that maxima were observed in mid-summer. Phytoplankton was composed of a mixture of Diatoms, Cryptophyceae and Chrysophyceae in both years but diatoms more prevalent in 2013. Average primary productivity in 2017 was highest nearshore (8.6 mg C m^-3 hr^-1) and lowest in the eastern basin (3.9 mg C m^-3 hr^-1).  Primary productivity was typically dominated by nanoplankton (2-20 ?m) with 38-50%, followed by picoplankton (<2 ?m) with net plankton (>20 ?m) contributing the least. Taxonomic composition, species diversity and primary productivity will be explored in order to relate the importance of seasonal succession of phytoplankton in understanding the changing ecology of Lake Ontario.

1. Keyword
phytoplankton

2. Keyword
productivity

3. Keyword
Lake Ontario

4. Additional Keyword
seasonality