ABOARD THE CCGS LOUIS S. ST-LAURENT–Without a microscope, most plankton are easy to miss. And when the tiny marine creatures do come into focus, they aren't much to look at.

Until you peer closer, and listen to what they have to say.

Way down near the bottom of the oceans' food chain, animals known as zooplankton drift on the currents, feeding on each other, eating still lower life forms such as bacteria and viruses, or in most cases, grazing on microscopic plant life, called phytoplankton.

As tiny, and as hard to love, as plankton are, scientists studying them say that if global warming makes things go bad for these organisms, the pain will run all the way up the food chain to humans.

"So in one way, the plankton are a type of canary in a coal mine," says John Nelson, a Department of Fisheries and Oceans scientist examining plankton at the Institute of Ocean Sciences in Sidney, B.C. "They will be affected by, and respond to, environmental change and we can detect this by studying them."

At first glance, zooplankton seem more likely to model for horror movie special effects than a "Save the World" poster.

The Arrow worm, known as the tiger of the zooplankton, is shaped like a torpedo. Its minuscule head has a halo of spines that the creature uses to swallow its prey whole.

Copepods, usually less than 8 millimetres long, are parasites with long antenna and a pair of leg-like limbs that the animal uses to push its hard-shelled body through the water in quick, jerking bursts of speed. Fish larvae love to eat them.

Other species of zooplankton look like microscopic shrimps, or jellyfish with sticky tentacles to trap food and cram it into their mouths. Some glow green – bright green – when bothered.

Kelly Young, 28, is a seagoing technician collecting millions of plankton in sample jars for study later in Nelson's lab, as CCGS Louis S. St-Laurent, pride of Canada's icebreaker fleet, steams through the Northwest Passage.

She has a soft spot for plankton.

"They're actually very pretty to look at," she said, after filling more jars with mushy sludges of sea life that looked like frozen margaritas.

Young is on a team of six Canadian scientists and students aboard the ship they affectionately call The Louis, which set sail for the Arctic's Northwest Passage from St. John's, Nfld., on July 20.

Twice each day, in the morning and evening, The Louis's crew slows the 5,300-tonne ship to a stop in the ocean so the scientists can go to work on the rolling deck. Young runs a piece of equipment called bongo nets because they look like two pairs of drums lashed together.

Little propellers mounted at the top measure the flow of water through long, fine-meshed conical nets. They dance in the frigid wind like Japanese kites when the equipment is winched over the side of the ship to be lowered 100 metres into the ocean.

The nets are quickly hauled back in, at 1 metre per second, so that fish and most other sea animals bigger than plankton escape. Young then washes her catch into small buckets, called cod ends, on each end of the four nets.

She bottles some of the concentrated samples in ethanol to preserve the plankton for DNA analysis. Others end up in formalin, a kind of embalming fluid, so different species of zooplankton can be catalogued, and the number in each group counted.

She kept one of her captives alive long enough to explain the attraction of animals few people ever see, let alone care about.

The pteropod, or "winged snail," was shaped like a manatee, but was as small and delicate as a fly fishing lure, an opaque organism with an orange tail, beating its appendages like wings against the swirling currents in a gently tilted sample jar.

So far, scientists haven't seen any plankton species go extinct, Nelson said from Barrow, Alaska, after a separate, two-week research voyage. But they are closely watching Pacific Ocean plankton found in the Arctic to see if they begin reproducing as sea temperatures rise.

"If a Pacific species was established in the Arctic, this would really be news," he says. "But we have not detected this yet. What could happen in this scenario is that, if the invader out-competes the native species, this could lead to fundamental changes in ecosystem function."

For instance, a smaller, invading species of plankton might replace a larger one, denying fish that used to eat the bigger plankton a key source of food, Nelson says.

Another instrument scientists use aboard the icebreaker is known as a rosette, from the circle of 24 tubes that capture water samples. They are analyzed for their salt content, various chemicals and nutrients, including oxygen content, all to assess the effects of global warming on the northern oceans.

The Arctic is one of the most unforgiving places to learn about Earth and the state of her health. It is also a very expensive place for scientists to work, so it has long been neglected by field researchers.

As concern builds over rising temperatures, the once ice-bound Northwest Passage is opening up to scientists eager to get a better look at what is happening to a region thought to be most vulnerable to early damage from climate change.

Vast areas of the Arctic are still scientific black holes, where researchers have yet to gather hard data, says Jane Eert, science coordinator of the Three Oceans Project, a federal study of Canada's Arctic, Atlantic and Pacific oceans.

For years, scientists trying to figure out what is happening to Arctic ice have relied on measurements recorded by pings from U.S. navy nuclear submarines cruising stealthily under the ice cap from Alaska to the North Pole, during the Cold War, says Eert, 49.

When the Soviet Union collapsed, and relations between Washington and Moscow warmed, the U.S. military was less worried about potential enemies knowing where its subs had been and declassified the ice data. It seemed to show the ice was thinning dramatically.

"Nobody really quite noticed the submarines were running across the outside edges of the Canadian archipelago," the islands scattered across Canada's Far North, "where for all we know, the ice was getting thicker," Eert says.

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"The ice doesn't stay constantly thick over the whole area. It moves around. So if you take measurements only in one spot, and make global conclusions from that, you might be going wrong."

A physical oceanographer, Eert leads the scientific team aboard The Louis. It's her 10th voyage on the ship since 1999. Between 10 and 15 per cent of the Arctic Ocean is what Eert calls a data hole. It will take years' more research to fill it in with solid information, she adds.

After years of reports that vast areas of Arctic ice are melting as the seawater below, and air above, warm up, scientists have discovered that dramatic changes in the past three years are the result of shifting winds, perhaps caused by climate change.

Enormous amounts of ice have "been exported from the Arctic," driven by winds that are shifting as the climate changes, which pushed the ice into ocean currents that delivered it to the North Atlantic, Eert says.

"The multi-year ice in the polar pack didn't melt in the Arctic Ocean,'' she says. "It moved out and what's left in the Arctic is thinner than it was."

That doesn't mean some Arctic ice isn't disappearing altogether, just that the process is not as simple as some reports suggest, Eert says.

Old ice that has shifted south from Greenland may have a counter-effect on the climate, which is just one of the many pieces of a very complex jigsaw puzzle that scientists are trying to piece together as they attempt to predict the effects of global warming.

"The guys who are running the long-term climate models have a tough problem," Eert says. "They're looking at really long time scales, and as result they can't look at a lot of details for each year.

"In order to get the results before you die, you have to fudge some things. And what they fudge is the small-scale stuff. But it turns out that probably the small-scale stuff is important and fudging it gives you wrong answers."

Ordinary people may help answer some of the Arctic scientists' most vexing questions. Eert's team brought along 200 new beer bottles, donated by Sleeman and Molson, which they are tossing overboard in the Davis Strait, Baffin Bay and other parts of the Arctic.

Inside each sealed beer bottle is a printed message asking anyone who finds it to contact the research team. Most have extra messages written by schoolchildren, with their own appeals for help for a project that's a cheap way to map ocean currents.

Up on the ship's bridge, Andre Pelland uses binoculars and his long experience to read icebergs birthed in Greenland, pack ice that the ship breaks through in the Arctic, and other ice conditions.

Pelland works aboard The Louis for the Canadian Ice Service, a federal agency that uses observations from radar satellites that can see through clouds, along with reports from monitors in aircraft and on ships, to produce detailed reports.

The shipping industry relies on them to steer vessels clear of icebergs and other hazards.

Pelland, 49, is The Louis's Ice Man. He started out as a weather observer in Resolute Bay 25 years ago, when he filed reports by a clunky Teletype machine.

Now he uses a digital tablet to log the ice, and files updates to headquarters by satellite Internet link.

The latest maps show above-normal concentrations of ice across a huge region in western Hudson Bay and James Bay, while some areas farther north have less ice than usual. Deciding what that all means is above Pelland's pay grade.

But he knows this for sure: the frozen North that captivates him is far too precious to lose.

"It's the last frontier," he says wistfully, the ship's rumbling diesel engines propelling her steadily north.