Aerial shot of a lake with two different shades of green

Exploring Harmful Algal Blooms

The longest-running experiment at IISD Experimental Lakes Area has involved adding phosphorus and nitrogen to a lake since 1968 to study nutrient contributions to algal blooms.

Researching the effects of nutrients on algal blooms and phytoplankton in lakes was the reason that the research site was founded back in 1968. It found that phosphorus is the main factor in algal growth.

Since 1990, no nitrogen has been added to this lake (Lake 227), but we have continued to add phosphorus. Despite the absence of artificial nitrogen inputs, algal blooms have not diminished. This and other studies have demonstrated that phosphorus control is highly important to limit algal blooms.

This research project has also supported multiple studies on nutrient and contaminant cycling. For example, in 2017 we started a research project to explore the potential role of iron in affecting harmful algal blooms.

In 2019, we also started intentionally eutrophying two lakes (a process that will take about two years) so we can determine the necessary preconditions for harmful algal blooms—all with the ultimate goal of targeting one factor per lake to reduce and prevent these blooms from occurring.

This research has been developed and carried out in collaboration with multiple researchers across Canada including the universities of Waterloo, York, Wilfrid Laurier, Toronto, and New Brunswick.

Project details