Trophic Ratios as Ecological Status Indicators: Examples from Lake Ontario

Session: Great Lakes Lower Trophic Level Community Dynamics (1)

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

Abstract

In recent years there has been a reinvigorated push for a more holistic food-web approach in surveys of aquatic ecosystems, wherein aspects of all trophic levels, as opposed to only direct linkages (e.g. uptake or predation), are considered.

Trophic ratios (e.g. zooplankton:phytoplankton biomass) can be used as an approach to assess disruptions in the linkages between trophic levels. They demonstrate the efficiency with which energy is transferred up the food chain, with higher ratios indicating more effective linkages between levels. Ratios are reduced when there is inefficient energy transfer as production is left unutilized, indicating disruptions to the food web.

Using a suite of trophic ratios to describe bottom-up and top-down food web processes, we compare and contrast Lake Ontario and its Areas of Concern, specifically Hamilton Harbour, Toronto Harbour, and the Bay of Quinte to determine if energy is efficiently transferred through the food web from phytoplankton to zooplankton to fishes consistent with other freshwater ecosystems of similar trophic status.

Twitter handle of presenter
@rockinrobin03