Research Shows Healthy Plankton Populations – What Do You Think?
Posted on: November 1, 2017

Phytoplankton? Zooplankton? What are they? Why are they so important to aquatic ecosystems? (2’23” video clip)

What’s Your Take?

Organizations involved in Thunder Bay harbour cleanup would like to know what you think. Here’s a bit of background:

Plankton are important microscopic organisms that live suspended in water, forming the base of the food chain. In the late eighties, at the outset of the Remedial Action Plan, or harbour cleanup plan, plankton populations were classified as “impaired.”  This decision was made in the absence of sound data or assessments to make such a determination. Take a look at the following information, then let us know what you think. Do we have enough information in-hand to change plankton’s status to “unimpaired?”

Status Linked to Improved Harbour Water Quality

When harbour cleanup began in the late eighties Thunder Bay was a highly industrialized harbour. Municipal and industrial effluent from multiple sources impacted water quality. Additionally, environmental regulations were less stringent than they are today. Based on these degraded environmental conditions and poor water quality, plankton populations were assumed to be impaired, even while no formal assessment had been carried out.

Since that time, harbour water quality has seen substantial improvement. Factors like the following have played an important role in this improvement:

  • industrial and municipal effluent treatment upgrades
  • industrial closures
  • improved stormwater management.

Research Supports “Unimpaired” Status

Studies document this improved harbour water quality and decline in contaminant and nutrient loading. As a result, agencies involved in the Thunder Bay Remedial Action Plan, such as Environment and Climate Change Canada and the Ontario Ministry of the Environment and Climate Change, are confident that there is no reason to be concerned about the health of plankton populations, and no action necessary. These agencies are recommending that the status of phytoplankton and zooplankton populations be changed to “unimpaired.”  They’d like to know if you agree. The following document provides more detailed information:

Key Findings 

  • Despite the elevated levels of Total Phosporous (TP), primarily in the Kaministiquia River delta area, nuisance algae has not been reported during the monitoring surveys, which is likely due to the capacity of the lake to dilute concentrations of TP below the level that would cause algal blooms
  • The industrial landscape of the Thunder Bay Area of Concern has changed substantially in the past decades in that several industries that contributed high loadings of nutrients, Five-Day Biochemical Oxygen Demand (BOD5), and other contaminants, have closed and thereby lessened the load to the receiving environment
  • In terms of the three remaining point sources of nutrients and contaminants, treatment upgrades and/or process changes at these facilities have significantly improved effluent quality which is routinely monitored for various contaminants and acute and chronic toxicity tests.
  • The study area is not phosphorus limited, and chlorophyll-a concentrations did not likely result in undesirable levels of algae. Moreover, the AOC supports a more diverse fish community than adjacent areas.

Get in Touch

Here’s how to let us know whether you think this item should be removed from the list of local concerns:

Call – 807-343-8514 – you’ll get a real person – Jim Bailey – Remedial Action Plan (RAP) Coordinator

Email – jfbailey at lakeheadu dot ca

Write  –  Our address is listed at the bottom of this page.

Comment – Using the brief comment form below.


Ongoing Monitoring

Monitoring of water quality and plankton populations in the Thunder Bay Area of Concern will continue every six years through the Great Lakes Nearshore Index Station Network. Monitoring was previously carried out in 2005 and 2011 with monitoring planned for the summer of 2017 and again in 2023.

A Plankton Overview from Biology Online

Biology Online provides the following information about plankton:

Plankton are microscopic organisms that live suspended in the water environment, and form a very important part of the freshwater community. They move via convection or wind induced currents. In almost every habitat of a freshwater ecosystem, thousands of these organisms can be found, and due to their small size and simplicity, they are capable of occupying large expanses of water and multiplying at an exponential rate. 

Plankton can be subdivided into two categories.

  • Phytoplankton – Phytoplankton are microscopic plants which obtain their energy via photosynthesis. However, some species of bacteria are also capable of photosynthesis and also fall under this taxonomic category. They are important to the ecosystem because they are part of the primary producing community and assist in recycling elements such as carbon and sulphur which are required elsewhere in the community.
  • Zooplankton – Zooplankton consist mainly of crustaceans and rotifers, and on the whole are relatively larger than their phytoplankton counterparts.

RAP Background

Thunder Bay’s harbour was listed in 1987 under the Canada – U.S. Great Lakes Water Quality Agreement, as one of over forty environmental “Areas of Concern” around the Great Lakes. Urbanization, industrial and municipal wastewater discharges and habitat degradation were contributing factors. Contaminated harbour sediment, water quality issues and also concerns about the health of fish and wildlife populations were cited as problems requiring remedial action.

The Thunder Bay Remedial Action Plan, or RAP, supported by Environment and Climate Change Canada, the Ontario Ministry of the Environment and Climate Change, the Ontario Ministry of Natural Resources and Forestry and Lakehead University.


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