BACTERIAL AND PHYTOPLANKTON PRODUCTIVITY IN THREE EUTROPHIC ENVIRONMENTS WITH CONTRASTING NUTRIENT REGIMES

Heterotrophic microbial activity in nutrient enriched environments is often masked by excess autotrophic activity. The present study will examine direct measurements of both bacterial and phytoplankton productivity using radioisotope tracers in three eutrophic habitats within the Lake Ontario basin. While the study sites, Hamilton Harbour, Toronto Harbour and the Bay of Quinte, all experience phosphorus enrichment to some degree, the underlying nutrient regimes are different in terms of P, N and Si resulting in fundamentally different food web processes. In the highly urbanized Toronto Harbour watershed for example, bacterial productivity averaged 2.0 mg C m^-3 h^-1 over the May – Oct (2019) period and was about double what observed in the more rural Bay of Quinte (May – Oct, 2018). By contrast, primary productivity in the Bay of Quinte averaged 44 mg C m^-3 h^-1 compared to about 17 mg C m^-3 h^-1 in Toronto Harbour over the same time frame. The goal of the current work is to explore how heterotrophic and autotrophic processes within the microbial and planktonic food web are affected by differing nutrient regimes.

Primary Presenter: Mark Fitzpatrick, Fisheries and Oceans Canada (mark.fitzpatrick@dfo-mpo.gc.ca)

Authors:

Mark Fitzpatrick, Fisheries and Oceans Canada  (mark.fitzpatrick@dfo-mpo.gc.ca)

Heather Niblock, Fisheries and Oceans Canada  (heather.niblock@dfo-mpo.gc.ca)

Mohiuddin Munawar, Fisheries and Oceans Canada  (mohiuddin.munawar@dfo.mpo.gc.ca)

Warren Currie, Fisheries and Oceans Canada  (warren.currie@dfo-mpo.gc.ca)