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Algae

 

More than 300 Species in the River!

Microscopic algae, Merismopedia elegans.

A cluster of Merismopedia elegans algae.

Alga diversity is an excellent indicator of water quality. When a river's water quality is good, the species of algae that live in it will be diverse.

During the Rideau River Biodiversity Project more than 300 species of algae were observed in the Rideau River. Most of these species belonged to the cryptophytes group, which are organisms that resemble diatoms and occasionally sport flagella. The presence of numerous species of cryptophytes, over and above the general diversity of the algae, is a sign that the water quality is basically good.

Algae were particularly diverse in the wetlands around Merrickville and Smiths Falls.

Algae are also able to tell us about the amount of fertilizer (phosphorus and nitrogen) in the water. In effect, the proliferation of certain species of algae indicates an abundance of fertilizers.

For example, during the Project, phosphorus levels and algal density were high within the City of Ottawa. Large floating mats of decaying algae were visible along the shorelines. This is a common site along many urban Ontario rivers.

Algal Masses: A Kind of Pollution?
Masses of algae near shore.

Masses of algae near shore, near Manotick.

Not really. Algae are a normal and essential part of a healthy river ecosystem. However, when there is too much phosphorus in the river, the algae proliferate excessively, and thereby place disproportionate pressure on the ecosystem.

After algae die they decompose while floating on the surface. Even large clusters do not harm plants or animals (humans included), but they return little benefit to the river and interfere with some recreation activities.

In extreme cases, the decomposition of the algae causes anoxia, which is an insufficiency of dissolved oxygen in the water. This phenomenon, which can be fatal to sensitive species (such as those species of fish that happen to be sportfish), occurs in only a few places in the River.

To eliminate the algal masses from the Rideau River, phosphorus levels must decrease. Discover how you can contribute to this reduction.


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 Algae
Arrow.
Arrow.
Bullet.
Bullet.
 Don't Overlook...
Arrow.
Arrow.
Arrow.
Arrow.


Two men in a boat.

Sampling algae in springtime.

A Project of the Canadian Museum of Nature
 Images: Paul Hamilton, Jean Lauriault, Linda Ley