Sharon Writes

ON Nature, Summer 2010

by Sharon Oosthoek

Go outside and play. It’s a rare child who hasn’t heard those words, and now there’s another reason to heed them – better eyesight. Australian and Singaporean researchers have found the more time kids spend outdoors, the less likely they are to be nearsighted.

 From 2003 to 2005, researchers with Australia’s University of Sydney gave more than 2,000 12-year-olds eye exams, and then asked them and their parents how much time they spent outside.

 The average was 2.39 hours a day, but the children who exceeded that were less likely to be myopic compared to those who didn’t, regardless of confounding factors such as their parents’ myopia. Researchers at the National University of Singapore, who conducted a similar study of more than 1,200 teens in 2006, came to the same conclusion.

 So what’s going on? Do kids who spend more time outside spend less time straining their eyes reading or playing video games? No, say researchers. In fact, “close work” had little effect on eyesight.

 Light may be the answer.  According to the Australian researchers, “Light intensities are typically higher outdoors than indoors, and pupils will be more constricted outdoors. This would result in a greater depth of field and less image blur.”

 The findings come at a time when myopia among children appears to be on the rise: in the West, one in three kids is nearsighted and in some highly urbanized East Asian regions, it exceeds 80 per cent.

ON Nature, Spring 2010

by Sharon Oosthoek

Invasive earthworms alter nutrients on which northern hardwood trees and plants depend.

It sounds like a bad Hollywood film, but truth can be stranger than fiction.

While gardeners love to see earthworms in their soil and eco-conscious apartment dwellers rely on them to compost food waste, what most people don’t know is that the vast majority of worms in Ontario are in fact invasive.  Furthermore, scientists recently discovered that the earthworms’ ability to decompose organic matter makes them a growing threat to our hardwood forests, including Canada’s iconic maple trees.

The vast majority of the approximately two dozen species of worms we see today arrived with European settlers more than two centuries ago in ships’ ballast and agricultural products.  (Before that, only two species of worms were in Ontario.)

But the very trait that makes them the darling of gardeners everywhere also makes them a menace in Ontario’s hardwood forests. European worms are much better than native species at munching through leaf litter.  In doing so, they alter the structure of phosphorous and nitrogen – nutrients on which northern hardwood trees and plants depend – such that they are no longer bound up with organic matter and they leach away with the rain.

A 2008 study of northern Minnesota hardwood forests found significantly smaller growth rings in maple trees from forests with European earthworms compared to worm-free forests. “Our research would apply to the hardwoods of southern Quebec and Ontario’s maple forests,” said University of Minnesota forest ecologist Lee Frelich, who worked on the study.

While European worms have been here for more than two centuries,  according to Frelich it takes roughly 1,000 years for a hardwood forest to adapt to such drastic change.  And as the climate warms, these worms are thriving farther and farther north.

While worms move five to 10 metres a year on their own, their wide dispersal is believed to be mostly due to fishermen transferring bait from one lake to another. In 2008, Trent University graduate student Stacy Gan found European earthworms on Akimiski Island in James Bay; their eggs probably arrived  in soil on the runners of float planes carrying goose hunters. Before that, worms had not been found farther north than Moosonee.

ON Nature, Winter 2009/2010

by Sharon Oosthoek

Round gobies were first discovered in the St. Clair River in 1990, likely arriving through ballast water from ocean-going ships.

Fisheries biologists have unexpectedly discovered round gobies in the Thames, Sydenham, Ausable and Grand rivers and are now sounding the alarm over how this invasive fish may affect endangered species.

The Great Lakes tributaries were long thought to be immune to such an invasion thanks to their status as Canada’s most diverse aquatic ecosystem. It was thought that since each ecological niche was taken up, invaders could not gain a foothold.

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ON Nature, Spring 2009

by Sharon Oosthoek

Two dominant and much discussed threats to the boreal forest are industrial interests and logging. Now another threat has surfaced. According to researchers from Queen’s and York universities, lakes in the forest are suffering from “aquatic osteoporosis” due to declining calcium levels.

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ON Nature, Spring 2009

by Sharon Oosthoek

Cerceris fumipennis wasp with its beetle prey. This native wasp can determine in as little as 30 minutes if emerald ash borers are in the area. (Mike Bohne/U.S. Department of Agriculture Forest Service)

A wasp native to Ontario may soon be pressed into service as a lead investigator into potential infestations by emerald ash borers.

Trials that University of Guelph researchers conducted and the Canadian Food Inspection Agency (CFIA) partially funded show that Cerceris fumipennis can determine, in as little as half an hour after leaving its nest in search of prey, whether invasive beetles are in the area.

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ON Nature, Winter 2007/2008

by Sharon Oosthoek

Oliver Haddrath stretches out his hand, palm up. He is holding what little remains of an ancient predator that once dominated the waters of Lake Ontario. Seated in a tiny, well-ordered office on the third floor of Toronto’s Royal Ontario Museum (ROM), surrounded by flow charts showing genetic links among long-dead creatures, the scientist’s attention is focused solely on the thumbnail-sized object resting in his hand. Despite his six-foot-one frame and broad shoulders, Haddrath has the air of a child trying to contain his excitement. He gazes at the yellowed, pockmarked vertebra sealed in a plastic bag. “Six-hundred-year-old fish bone,” he says, striving unsuccessfully for an even tone.

Haddrath places the vertebra in a small cardboard box atop two fistfuls of Atlantic salmon bones that also date back to the 15th century. The bones are among the last relics of physical evidence that Lake Ontario was once home to these huge freshwater fish, a species that could weigh as much as 20 kilograms – more than any other freshwater salmon in North America.

Full article

ON Nature, Spring 2008

by Sharon Oosthoek

Getting a handle on polar bear populations can be tricky.

How many polar bears live in the north? Counting animals in the wild has never been a straightforward or easy task, but because climate change has altered polar bear habitat so markedly, scientists are finding that deriving an accurate count is proving especially difficult.

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