Fraser Lake, BC, Canada
There is unusual abundances of blue-green algae on West end of Fraser Lake.
Observation by Juanita Heron
There is unusual abundances of blue-green algae on West end of Fraser Lake. I have included photographs in this post.
Comments by Tom Okey
Fraser Lake, at 700 m above sea level in the Interior Plateau of British Columbia, is naturally a relatively low-nutrient (oligotrophic) lake, but various human activities have increased the nutrients such as Phosphorous. This has led to the presence of blue-green algae (cyanobacteria), decreased water clarity, and decreased oxygen. An examination of the Fraser Lake watershed (Figure 1) shows that the west end of Fraser Lake receives runoff and nutrients from agriculture, forestry, and urban areas surrounding that part of Fraser Lake including the village sewage treatment system, and from the inflowing Stellako-Endako River system which also drains some agricultural and forestry areas and Burns Lake further upstream. Visible blue-green algae in the western Fraser Lake is an indicator of this nutrient enrichment, or cultural eutrophication.
Climate change is known to increase algal blooms, particularly blue-green algae (cyanobacteria), in the following ways. Warming water temperatures, intensification of the hydrological cycle (e.g. rainfall patterns), and increased carbon dioxide all enhance harmful algal blooms either directly and indirectly (USEPA page). Subsequent blooms of algae in turn increase water temperatures further by absorbing more solar radiation, and they can ultimately decrease overall oxygen in a lake through microbial decomposition. Such algal blooms can thus create a feedback that reinforces a shift to a degraded state.