Lake environments are changing

Rousing the Rabble column by Roy Ronaghan, Nov. 25 Grand Forks Gazette.

An article on the Environment 360 Website about the transformation of Earth’s most northern lakes by global warming did not surprise me, what did was the speed and extent of the change to their ecologies with only a couple degrees of atmospheric warming.

Cheryl Katz, author of an article with the title On Thin Ice: Big Northern Lakes Are Being Rapidly Transformed focuses on Lake Baikal in Siberia, a lake the size of Florida and as deep as the Grand Canyon in the United States. It holds one-fifth of the world’s aboveground drinking water supply.

Katz describes the lake as unique. “It’s a Noah’s Ark of biodiversity, home to a myriad of species found nowhere else on earth. It’s also changing fast, due to heat-trapping greenhouse gases that are increasingly disrupting the climate.”

Baikal’s surface waters are warming quickly. Over the past 25 years the increase has been at least 2° C (3.6° F), which is twice the speed of the warming of global air temperatures, according to new research. The time that the lake is ice covered has been shortened by nearly three weeks since the mid 1800s and the ice is thinner by five inches since 1949. Scientists predict that the Baikal could soon be ice-free for a month longer than at present.

The rapidly changing lake climate is having a noticeable impact on its cold-adapted creatures, including a freshwater seal, the nerpa. Warmer winters cause the seal’s fertility rate to drop. The population of omul, a species of whitefish, has also dropped severely.

Green sponge forests in the lake are dying from an unknown pathogen and algae mats are choking wide areas of the lake bottom near shore where the greatest biodiversity is located.

Baikal is not the only lake in the world showing signs of rapid change from rising temperatures. The Great Lakes, shared by Canada and the United States, are also changing.  Like most lakes above the 40th parallel, their temperatures have risen. International research reports that surface temperatures rose by 2.7 degrees Fahrenheit or more between 1985 and 2009 which lessens winter ice and interferes with internal circulation and oxygen levels thus creating fertile breeding grounds for harmful algae.

Stephanie Hampton, an aquatic ecologist at Washington State University in Pullman and a member of the Global Lake Temperature Collaboration that is compiling an international database on lake observations says, “Lakes are very clearly telling us that there’s rapid warming worldwide.”

After reading Katz’s article and a few others I began to think about what the future might hold for Christina Lake. It is not large but it is already known to be one of the warmest freshwater lakes in Canada, a big plus for its tourism industry. It is also a source of potable water for a large part of the population.

Will it undergo extreme change?

The Christina Lake Stewardship Society (CLSS) recently issued an invitation to the annual review of its watershed management plan on Dec. 8. Participants are asked to list their three main environmental concerns pertaining the lake and the watershed. My main concern is with the effects of gradual warming of the water on the lake’s ecology.

Like the large lakes I have been reading about, are small lakes affected in the same way? Could Christina Lake become more acidic as atmospheric carbon dioxide levels rise? How might the ecology change? Will there be an increase in the growth of green algae? Will Eurasian milfoil flourish even more than it is now? Will existing species of fish survive?

These are questions I can ask, but not get answers to until the effects of climate change have been clearly identified and that will be some time in the future. The best I can expect is that the CLSS will continue its important work of  monitoring and reporting regularly on the lake’s health.