Rising temperatures put at least a quarter of marine life around P.E.I. at risk, paper estimates

The giant Irish sea moss that is found only in Basin Head, P.E.I., is among the marine organisms that will feel the impact of warming ocean temperatures in the decades ahead.

This strain of moss can itself tolerate warmer water, said Irené Novaczek, a former marine biologist with the federal Department of Fisheries and Oceans who now works alongside the Souris and Area Branch of the P.E.I. Wildlife Federation in the Basin Head area.

The problem is that it relies on the help of mussels to hold it to the bottom.

"The older mussels are, the less tolerant they are of heat," she said. "Those high, high summer water temperatures are getting to the point where all the mussels will die and then the moss will be gone." 

This is the kind of scenario that led a group of researchers based at Dalhousie University to publish a paper in the journal Nature Climate Change estimating that 90 per cent of the world's marine life is at either high or critical risk due to ocean warming trends.

The Aug. 22 article warns that those species will stay in danger if nations around the world continue to develop and use fossil fuels and maintain their current emissions levels through to 2100.

"Climate change poses a significant risk to marine life for the same reasons it poses a risk for species [on] land, including our own," said Boris Worm, a co-author and a marine ecologist with Dalhousie University. 

This is the effects of ocean warming by itself, but also its effects on oxygen and nutrient supply that affects the productivity of the ocean and the ability of its creatures to breathe.— Boris Worm

"So this is the effects of ocean warming by itself, but also its effects on oxygen and nutrient supply that affects the productivity of the ocean and the ability of its creatures to breathe."

The Dalhousie research suggests marine life closest to the equator will feel the impact first — but still, at least a quarter of species around P.E.I. are classified as being at either high or critical risk.

Higher temperatures recorded

Novaczek is seeing that first-hand. Sea water temperatures in the Basin Head estuaries of northeastern P.E.I. have been gradually increasing in the past decade, and researchers are now recording highs of up to 30 degrees.

The rising temperatures are forcing some marine plants and animals north in search of cooler water, Novaczek said — but they don't always find what they need.

"Those species are going to have to move north out of this southern Gulf [of St. Lawrence]. They're going to head up the Labrador coast. And some of them will do well, but others won't find the kind of habitat they need, either for nesting or reproducing or feeding," she said. 

She gave the example of herring, a fish stock that has seen declining numbers in the Gulf of St. Lawrence. 

Researchers have linked that to changes affecting microscopic animals in the water called zooplankton. Zooplankton serve as food for young herring and are critical to their survival.

Without enough zooplankton, "most of [the herring] die within two years, before they get big enough for anybody to fish them," said Novaczek.

Changing current practices

The Nature Climate Change article describes a scenario in which the risk to marine life is lessened through an "increase in sustainable development."

Novaczek said changing the outlook for marine plants and creatures will require a collective effort.

"We'll have to adapt to a radically different way of living to protect the ocean — which, you know, is our mother and feeds and protects us in many ways. She's gonna turn on us with climate change."

As ways of mitigating what that could look like, Novaczek pointed to reducing our emissions, planting more trees, stopping the use of fossil fuels, and supporting agricultural reform.

Or else, she said, "P.E.I. will eventually become unlivable altogether."