The impacts of climate change will only add to the challenges already being faced by Lake Winnipeg. As Manitobans noticed last summer, the blue-green algae blooms in the lake's north basin are already a concern. However, the blooms are not just unsightly for cottagers and sailors on the lake. They are a real threat to the lake's inhabitants. After the algae blooms, it dies, absorbing precious oxygen needed by the fish in the lake as it decays. These blooms are only expected to increase in frequency and extent as the lake water warms. This very visible sign of the lake's distress is only one of the problems facing our favourite nature areas in Manitoba due to climate change and increasing pollution.
For over 100 years, Lake Winnipeg and Lake Manitoba have been home to Manitoba's commercial fishery. The majority of the fishery's production is sold out of the country and represents over $30 million annually for Manitoba's economy -- a significant contribution. About two-thirds of this amount is generated by the commercial fishery on Lake Winnipeg. Over 1,000 licensed fishers are employed on this lake, harvesting a variety of species including pickerel, goldeye, sauger and whitefish. Several smaller lakes in southern and northern Manitoba are also fished commercially, including Southern Indian Lake.
Climate is the single most important factor controlling biodiversity and the distribution of aquatic organisms in Canadian Lakes. This finding is true for Lake Winnipeg, which is more vulnerable than other lakes to a warming climate because of its relative shallowness and a lack of thermal refuge for cold water fish. As climate change proceeds, the lake's temperature, pH, and oxygen levels are expected to be altered. These changes, either individually or collectively, will impact the health, composition and availability of fish. Research already shows significant temperature increases in the south and north basin of Lake Winnipeg since 1909 to 2004, with 1C increase in average water temperatures in September in the north basin and a 1.9C increase in average temperatures in August in the south basin. Ice break up has also occurred earlier during this same time period.
Rising temperatures could benefit warm-water species such as walleye, yellow perch and white bass by creating conditions that promote the growth of offspring better able to survive through shorter winters. As most Lake Winnipeg fish species are nearer to their northern rather than their southern limit, climate change might not cause a large change in the overall fish community. However, warming waters could cause cold-water species like whitefish to die out or become less productive. Of the 56 fish species found in the northern and southern basins of Lake Winnipeg, the thermal tolerance of five to 17 species in the north basin might be exceeded by the maximum surface water temperatures predicted by current climate scenarios. In the south basic 16 to 31 species, or over half of the fish species, could be impacted.
Invasive species might pose an additional challenge for Lake Winnipeg. These species might thrive due to the warmer lake temperatures and could appropriate or destroy the habitat of native species. For commercial fishers, the arrival of invasive species could be negative if they displace current economic species, or beneficial if there is a market and ability to harvest the new arrivals. Exotic zooplankton, such as the E. coregoni might also become more common and compete with other native species.
In many ways forewarned is forearmed. A clearer understanding of the likely effects of climate change will help fishers, First Nations and the general public to adapt to the changes we are already seeing in the lake. But there are things we can do now to help the lake in its battle against the elements.
The catch basin of Lake Winnipeg represents only a small portion of the entire watershed region. Each action upstream affects Lake Winnipeg and every attempt to limit nutrient loading or pollution of the rivers and streams leading into Lake Winnipeg will help the lake heal and adapt to climate change concerns in the future.
One unique approach to upstream watershed management is a system that was successfully implemented in the New York City watershed. In 1989 the city received an order from the Environmental Protection Agency to install a new filtration system costing an estimated six to eight billion dollars for the population's drinking water. Balking at the high cost, the city looked for an alternative approach and found one upstream in the Catskills region. Instead of building a treatment facility to clean the water after it's been polluted, New York decided to try to pay people to keep the upstream water clean. Called Payment for Ecosystem Services (PES) the plan ended up costing roughly one quarter of the original estimate for the treatment plant.
Manitoba is already experimenting with this form of local watershed protection in the Alternative Land Use Services (ALUS) research project in the rural municipality of Blanshard. The first of its kind of Canada, farmers and landowners will be paid to maintain and enhance four different landscape types that have public environmental benefits associated with them: wetlands, ecologically sensitive lands, riparian areas and naturals areas.
Watershed management is only one of the many issues related to climate change that will need to be addressed and PES is only one of the many tools at our disposal for adaptation.
David Runnalls is president and CEO of the International Institute for Sustainable Development.