Canada's boreal landscape contains an estimated 1.5 million lakes and rivers – more than any equivalent land mass on Earth. As water flows through Ontario’s rivers, lakes and tributaries, calcium content in soft water lakes has been quietly and significantly declining, threatening aquatic life, the food chain and the ecosystem.
Biologist and York Professor Norman Yan (left) and his colleagues have been keeping watch on the environmental stressors on Ontario’s 250,000 lakes. Yan is the co-author of a recent study published in Science, which revealed that the calcium levels are significantly declining in hundreds of Ontario lakes. In 40 of these lakes, the researchers have identified the critical threshold of “aquatic osteoporosis” on one particular organism: Daphnia, a tiny water flea. The data was collected by the study’s lead author Adam Jeziorski (MSc ’05), a Queen’s doctoral student working with Yan in York’s Field Laboratory for the Assessment of Multiple Ecological Stressors (FLAMES) at the Ontario Ministry of the Environment’s Dorset Environmental Science Centre in the Muskoka Region (see YFile, Nov. 28, 2008).
Yan, a limnologist whose research expands from restorative ecology to biological invasions, is dubbed the “Lake Doctor” because of his dedicated research on saving Ontario’s lakes. He recalls a spring day when he sat looking at the data sets that formed the publication’s basis. “The effects of calcium decline were on the horizon and we had not realized what was happening,” he says. “I was stunned.”
What surprised Yan was that the level of calcium concentration in many of the lakes had approached or was below the threshold at which Daphnia can no longer survive. In 1989 when Yan wrote his doctoral thesis at the University of Guelph based on a study of the cadmium levels, he also investigated calcium levels in five species in Ontario’s soft water lakes. He knew that his study would have impact but he did not know that it would be so pronounced and widespread. It would take almost 20 years and studies of more than 20 species, when data from his earlier work would re-emerge to determine the critical threshold of calcium on aquatic organisms.
While there are many environmental stressors that can reduce calcium in lakes, known threats include acid rain, logging and forest regrowth. “Roughly half of an ecosystem’s re-usable calcium is in the trees,” says Yan. “The remaining amount must be obtained from the soil. When acid rain falls, it removes the calcium and carries it into the lake where it can’t be used by trees, which need calcium to regrow after an area is logged. That’s why knowing the capacity of soil is so important – it may never grow back.” The damage to the fragile ecosystem is non-reversible. “Calcium is not replaceable,” Yan iterates. “The mollusks, crayfish and snails cannot build their shells without it.”
To control further calcium decline, Yan says there must be a reduction in acid and sulphur dioxide emissions from the environment. Although policies have been put in place to control acidification over the past 30 years, he asserts that the ecosystem must be continually protected from these known stressors since scientists do not yet know how the stressors interact with each other.
Over the last three decades, Yan has widened his research on restorative ecology to examine ecology, plankton population biology and biological invasions. In 2003, Yan identified a spiny water flea whose invasion threatened aquatic life. While the study shows the impact of biological invasions on the ecosystem, the benefits of Yan’s research continue to expand to assist industries from mining to energy.
Collaboration: Central to research success
Yan’s research is one example of collaboration that is central to York’s research excellence. He believes in using multiple methodologies to allow for collaboration with other ecologists and biologists at York and global institutions, and regularly shares ideas and exchanges technical information with scientific colleagues. “I appreciate the role of chocolate in the cosmos,” he chuckles, suggesting that it is in the company and collaboration with his colleagues that is remarkable in the success of his research.
Of course, not all of Yan’s research has revealed such immediately exciting results. One study, in which Yan and his team believed that they could measure calcium levels through species eggs that are easy to extract and identify from sediments, revealed that there was actually no calcium in the eggs. The team then communicated the results of the study so that animal fragments could be used for subsequent tests.
“I spend half my time at York and half my time in the FLAMES lab,” Yan explains, “this is why my work is so collaborative – working with other scientists allows us to receive research funding as well as phenomenal data sets. It’s when you analyze long-term data sets collected by many researchers that new hypotheses emerge, such as this one regarding calcium decline.”
The proof is in Yan’s list of collaborators. Besides Jeziorski, the Science study included contributions from York PhD candidate Michelle Palmer and researchers at Queen’s University, Fisheries & Oceans Canada, Environment Canada's National Water Research Institute, Ontario’s Ministry of the Environment and Environment Canada.
Partnerships and support for Yan and his research colleagues’ fieldwork have come through the National Sciences & Engineering research Council of Canada, Ontario’s Ministry of the Environment, Environment Canada and Fisheries & Oceans Canada.
Submitted to YFile by Sana Mulji Dutt, research communications officer