Queen's University biologists find new environmental threat in North Amer...( Kingston ON A new and insidious env...)

Kingston, ON A new and insidious environmental threat has been detected in North American lakes by researchers from Queen's and York universities.

Along with scientists from several Canadian government laboratories, the team has documented biological damage caused by declining levels of calcium in many temperate, soft-water lakes.

Calling the phenomenon "aquatic osteoporosis," Queen's PhD candidate Adam Jeziorski, lead author of the study, notes that calcium is an essential nutrient for many lake-dwelling organisms. "Once calcium declines below a certain threshold, some keystone species can no longer reproduce," he says. "These species and other organisms that feed on them are endangered."

The study is published today in the prestigious journal Science.

The researchers examined a water flea, Daphnia, known to be a key component of many aquatic foodwebs. Having identified the calcium levels that would damage Daphnia in a laboratory setting, they worked with government scientists to assemble hundreds of "water quality time series" from across the province, explains Biology professor Norman Yan from York University, the Canadian research lead on the threat to aquatic life of calcium decline. "Our hope was to determine if damage was already occurring at key sites, and then see how common these conditions were across the province," he says.

However, calcium decline occurred in many lakes before people knew about the problem and monitoring programs had been put in place. By studying tiny fossils and other indicators in sediment accumulated at the bottom of each lake, Queen's paleoecologist professor John Smol, Canada Research Chair in Environmental Change, and his colleagues were able to reconstruct environmental trends over the past 200 years. The researchers found that key invertebrate species were disappearing in the lakes with declining calcium levels, often starting in the 1970s.

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