Nutrient loading and algal blooms

Nitrogen and phosphorus levels in water bodies

Graphic thumbnail: nitrogen and phosphorus levels in water bodies

This graphic contains two pie charts that summarize nitrogen and phosphorus trends between 1990 and 2006 in Canadian water bodies. Of 83 sites monitored for nitrate-nitrite, 28% had increasing trends, 12% had decreasing trends, and 60% showed no change. Of 76 sites monitored for phosphorus, 21% had increasing trends, 29% had decreasing trends, and 50% showed no change.

Close window

Algal blooms in Lake Winnipeg

Graphic thumbnail: algal blooms in Lake Winnipeg

This bar graph shows the trends in biomass of phytoplankton from late July to early September over the period 1969 to 2003, based on measurements from 1969, 1994, 1999, and 2003. Blue-green algae increased, but other phytoplankton showed no significant trend. In 1969 the biomass of blue-green algae was less than 1,000 milligrams per cubic metre; in 1994 it was less than 2,000 milligrams per cubic metre; in 1999 it was approximately 6,000 milligrams per cubic metre; and in 2003 blue-green algae had a biomass of approximately 10,000 milligrams per cubic metre. Biomass of other phytoplankton fluctuated between approximately 500 milligrams per cubic metre and approximately 1000 milligrams per cubic metre over the four sample years. An inset map shows the location of the Lake Winnipeg drainage basin, spanning the Prairie Ecozone+.

Close window

Harmful algal blooms in Quebec

Graphic thumbnail: harmful algal blooms in Quebec

This bar chart shows the number of water bodies with harmful algal blooms annually from 2004 to 2009 in Quebec. The graph shows an overall increase in harmful algal blooms. In 2004, 21 water bodies experienced harmful blooms. This increased to nearly 160 water bodies in 2007 and remained at about that level through 2009.

Close window

Great Lakes algal blooms

Graphic thumbnail: Great Lakes algal blooms

This map marks the sites where toxic algal blooms have been reported in the Great Lakes. It shows 6 sites in Lake Ontario, 7 in Lake Erie, 1 in the Georgian Bay, 2 in Lake Huron, 2 in Lake Michigan, and none in Lake Superior.

Close window

Species composition of phytoplankton in Lake Erie

Graphic thumbnail: species composition of phytoplankton in Lake Erie

This bar chart displays the relative species composition of phytoplankton in Lake Erie in 2003, 2004, and 2005. Data are shown as a percentage of total species in samples, based on a measure of the amount of each of five types of phytoplankton present in samples. In 2003 chlorophytes (green algae) were the dominant phytoplankton at 53%, while cyanobacteria, bacillariophytes, cryptophytes and crysophytes each made up less than 17% of the phytoplankton. In 2004 the balance was reversed and chlorophytes made up less than 5% of phytoplankton. Cyanobacteria (blue-green algae) increased two-fold from the previous year to 20% of the phytoplankton. In 2005 chlorophytes again made up the smallest part of the phytoplankton; 34% of the total phytoplankton in lake samples consisted of cyanobacteria.

Close window

Reductions in nutrient loading in Skaha Lake, B.C.

Graphic thumbnail: reductions in nutrient loading in Skaha Lake, B.C.

This graph, containing three lines, shows the reduction in nutrient loading in Skaha Lake, B.C., through measurements of phosphorus, chlorophyll a, and dissolved oxygen, from 1968 to 2008. Phosphorus decreased overall, with a peak of 45 micrograms per litre in 1967, followed by fluctuating levels in the 10 to 30 micrograms per litre range; then, starting in the late 1980s, a decline to values that were generally below 10 micrograms per litre. Chlorophyll a measurements started in 1978. Values fluctuated widely from close to 20 micrograms per litre to close to 0 micrograms per litre, with an overall decreasing trend. Dissolved oxygen increased steadily from the start of measurements in 1978, despite wide fluctuations, increasing from approximately 4 milligrams per litre in 1979 to approximately 8 milligrams per litre in 2008.

Close window

Harmful algal blooms in the ocean

Graphic thumbnail: harmful algal blooms in the ocean

This graphic consists of two satellite photos of the west coast of B.C. and Washington, one in natural colour and the other enhanced to reveal ocean chlorophyll concentrations. A bar on the side of the map shows how the colours in the enhanced photo depict chlorophyll concentrations. The bar shows colours that represent ranges from 0.04 to 60 milligrams per cubic metre. Chlorophyll concentrations are generally low in deep water off the coast, ranging from approximately 0.5 milligrams per cubic metre to approximately 1.4 milligrams per cubic metre. Most of the coastal zone has higher concentrations of chlorophyll, with the exception of the deep waters of the central and northern Strait of Georgia. The highest concentrations, between 10 milligrams per cubic metre and 60 milligrams per cubic metre, are found off the west coast of central Vancouver Island and off the coast of Washington State.

Close window