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.

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.

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.

But a team of scientists from the universities of Toronto and Guelph, and the Ontario Ministry of Natural Resources, stumbled across the round gobies starting in 2006 while checking on the health of various tributaries in southwestern Ontario.

“We didn’t anticipate finding round gobies. That wasn’t the goal of the work,” said Mark Poos, a PhD student in biology at the University of Toronto.

Poos is lead author of a recent study showing that gobies can potentially harm up to 89 per cent of fish species and 17 per cent of mussel species in the tributaries.

Round gobies push other fish, such as the threatened eastern sand darter, out of their spawning beds and will in some cases eat their eggs, thereby reducing their populations.

Gobies threaten mussels more indirectly, by decreasing the number of fish on which they rely when they’re young.

Young mussels, such as the endangered snuffbox mussel, attach themselves to the gills of at-risk fish. Without the help of their hosts, they couldn’t move from one river system to another, their geographical ranges would shrink, and a single catastrophe could wipe out an entire species of mussel.

Round gobies were first discovered in the St. Clair River in 1990, likely arriving through ballast water from ocean-going ships. But until recently, they hadn’t found their way into the Great Lake’s tributaries.

“It truly is a new invasion,” said Poos.  “The question is why. That’s the one thing I don’t think we have a handle on.”

There are some educated guesses, however.

Perhaps the goby population has now grown large enough to push its way into the tributaries. Or maybe there are two genetic types of gobies – one of which is more invasive than the other – and it’s the hyper-invasive type that has now made its way into the Great Lakes system.

Whatever the cause, scientists such as Poos hope to influence those who fish in the Great Lakes’ tributaries not to transfer bait – which could include gobies – caught in one area to another.

“We’re not entirely sure what’s going to happen,” says Poos. “These fish and mussel species are already getting hit by other things – habitat alteration and turbidity. So when a new species comes in that can compete with them, I think it poses a serious problem.”

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.

Nearly all life forms need calcium, even tiny water fleas. Scientists have discovered that calcium levels are so low in some forest lakes that Daphnia, a species of water flea that is key to the food chain, is experiencing greatly lowered reproductive rates, jeopardizing both its own survival and that of the small fish that feed on it.

In a surprising twist, the dearth of calcium is linked to a decades-old environmental threat many people considered largely solved – acid rain. Scrubbers installed on industrial smokestacks starting in the late 1970s have helped decrease levels of sulphuric and nitric acid, the main ingredients in acid rain, allowing many lakes to regain their normal pH levels.

“This is an environmental story that’s been missed,” says Queen’s biology PhD student Adam Jeziorski, lead author of a study published in the journal Science in November. “Over the last 10, 20 years, acid rain has fallen out of the public eye. The pH level is recovering so lakes are becoming less acidic, but biological recovery, that is, plants and animals in the lakes, has been lagging.”

Because sulphuric and nitric acid are positively charged, as is calcium, the elements compete for negatively charged binding sites in the soil around the lakes. The result is that calcium leaches from the soil and drains into the water. For centuries, the soil slowly released calcium into the lakes. When the acid rain phenomenon was at its peak, an abundance of this element was released, leaving precious little calcium behind in the soil. To compound the problem, calcium is produced largely by mineral-rich rock breaking down over time and is therefore replaced very slowly.

The team looked at 200 years’ worth of sediment in three lakes: Plastic Lake near Dorset, Ontario, in the Muskoka region, Little Wiles Lake in Nova Scotia and Big Moose Lake in New York State. The researchers found that key invertebrate species were disappearing in the lakes with declining calcium levels, often starting in the 1970s. It was around the same time that the effects of acid rain on our ecosystems became apparent.

The researchers also combined existing data on 770 lakes, stretching from the Muskoka-Haliburton region to Kenora, and found a third of the lakes had calcium levels below 1.5 milligrams per litre, the threshold at which Daphnia can effectively reproduce. The levels in almost two-thirds of the lakes were at two milligrams per litre.

“It has really led to a whole slew of questions,” Jeziorski says. “It’s a jumping off point for new research: How is this affecting other species, the lake as a whole? What other changes in the lakes might we have missed?” Those levels, he adds, are much lower than levels were even 20 years ago and are likely to continue to drop.

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.

The traditional way of surveying – peering into treetops where the beetles congregate – is expensive, and spotting them can take days. The longer it takes, the more trees need to be felled, or inoculated, to stop the beetles’ spread – also expensive propositions.

The shiny green beetles, which in 2002 travelled from Asia to North America in packing materials, kill ash trees by destroying the water- and nutrient-conducting tissues under the bark. Two years ago, Steve Marshall, a professor of entomology with the University of Guelph, recruited Master’s student Philip Careless to see if the large, darkwinged wasps might function as an early warning system for an emerald ash borer infestation. The wasps do not kill beetles in sufficient numbers to control an infestation, but Marshall suspected that they might just “provide a natural and very low-cost approach to monitoring for emerald ash borers.”

Marshall’s earlier research at Rondeau Provincial Park confirmed that the wasp feeds on jewel beetles, including emerald ash borers. But no one had ever attempted to move wasp nests to areas at risk of beetle infestations to see whether they could be used as mobile surveillance units.

During the summers of 2007 and 2008, Careless used a backhoe to dig up earthen wasp nests in various parts of Ontario at night, when the females remain inside. He then drove them in a pickup truck to high-risk areas such as Windsor, where the first Ontario sightings of the beetles were confirmed in 2002.

The wasps reoriented themselves the next morning and then ventured out to find jewel beetles to bring back to feed their larvae. Many of those beetles were emerald ash borers.

On the basis of the speed of the fastest wasp observed – which flew 33.4 metres per minute – Careless was able to estimate how far a beetle infestation might have spread in any given area by calculating how long the wasp was gone from its nest. So, for example, a wasp that took 57 minutes to forage travelled just over 1,900 metres to catch the beetle and return to its nest. That meant that the beetle was caught within 950 metres of the nest site. Given that nests are spread out at regular intervals in a given area, estimating the extent of infestation and the trees that need to be cut down or inoculated become possible.

But before the wasps can be used as portable beetle detectives, Careless needs to figure out how to move the delicate nests without disturbing them. “The soil moves around a bit and, as [it] settles, the entrance to the [nest] tunnel can collapse,” says CFIA survey biologist Troy Kimoto. “Sometimes females will go back and dig it out; sometimes they’ll abandon it.” This summer, Careless will work with the CFIA to experiment with different ways to keep the females happy in their nests.

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.

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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.

Population surveys typically are carried out every decade or so, but with northern temperatures rising with each passing year, many people fear that the numbers of these predators will plummet between surveys, and that such a severe diminishment will be discovered too late. B

But an Ontario researcher has come up with a potentially simple, and inexpensive, solution. Queen’s University geneticist Peter De Groot hopes to “footprint” unique polar bear tracks in Canada’s north. Previous population studies of African rhinos and Indian tigers show that paw prints are unique to specific individuals, allowing scientists to get a good idea of how many individual animals inhabit a particular area.

If De Groot can show that the same can be done with polar bears, this method will supplement the time-intensive and expensive system of tranquilizing the animals, taking DNA samples to pinpoint unique individuals and then counting the individuals.

While this method, carried out by government scientists, produces highly reliable population estimates, it come with a roughly two-million-dollar price tag and takes several years to complete. Given that 13 discrete polar bear populations exist in Canada, such expensive population estimates can be conducted only every 10 years at best.

But, as the pace of temperature hikes induced by climate change quickens, population surveys must keep up. Moreover, population size determines hunting quotas. The bears’ habitat is changing so fast that the only way to set responsible quotas, argues De Groot, is to conduct more frequent population surveys. The survey he directs costs about $50,000 and can be undertaken every year. “It’s really easy,” he says. “You get on a Ski-Doo and go.”

De Groot has employed several local Inuit people, who are intimately familiar with the polar bears’ habits and habitat, to scour the landscape from March until May, looking for the animals’ footprints and photographing them for analysis.

Hundreds of the photographs are sent to Portugal-based Wildtracks, which specializes in footprint identification techniques using factors such as the distances between toes, and heel and toe footpads.

In the meantime, De Groot and his team will also collect feces and hair samples left near the prints, an analyze the samples for genetic information that will help determine whether the prints represent unique individuals. If, like the prints belonging to rhinos and tigers, a bear’s paw print is as individual as a person’s fingerprint, then De Groot’s system is viable and would allow bear surveys to be conducted with greater frequency.