Assessing Microbial-Planktonic Food Web Dynamics in Nearshore and Offshore Habitats of Lake Ontario

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

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

Abstract

Offshore pelagic food webs are dependent on the transfer of autochthonous production from lower to higher trophic levels while nearshore food webs may be more heavily influenced by allocthonous matter. These differences will likely affect the transfer of organic matter through the microbial-planktonic food web (phytoplankton, picoplankton, bacteria, heterotrophic nanoflagellates, ciliates) in both nearshore and offshore environments.  Lake Ontario is known to have strong nearshore to offshore gradients in terms of both autotrophic and heterotrophic production. For example, primary productivity was observed to be as high as 26.8 mg C m^-3 h^-1 in coastal Lake Ontario (Toronto Harbour) during the late summer of 2013 compared to 2.5 mg C m^-3 h^-1 offshore.  Likewise, bacterial productivity was as high as 5.9 mg C m^-3 h^-1 nearshore compared to <0.1 mg C m^-3 h^-1 offshore. The current paper will investigate the structure and function of the microbial planktonic food web in various nearshore (Hamilton Harbour, Toronto Harbour, Bay of Quinte) and offshore habitats around Lake Ontario in order to assess the relative impact of allocthonous and autochthonous matter in different ecosystems.

1. Keyword
carbon

2. Keyword
phytoplankton

3. Keyword
photosynthesis

4. Additional Keyword
heterotrophs

5. Additional Keyword
autotrophs

6. Additional Keyword
microbes