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Scientists study inlet's low oxygen

May 29 2012

International scientists are looking to Saanich Inlet research to help shape a global response to the rapidly growing problem of low oxygen in large areas of ocean.

As ocean chemistry shifts because of climate change or fertilizer leaching, the food web changes, with species that can survive in low oxygen conditions pushing out commercial species.

Research in Saanich Inlet shows species such as tiny shrimp, squat lobsters and small flat fish can live with remarkably little oxygen. "They're very highly adapted to low-oxygen conditions," said Verena Tunnicliffe, director of the Victoria Experimental Network Under the Sea project. Led by the University of Victoria, VENUS has an underwater observatory that provides information from Saanich Inlet through fibre-optic cables.

Commercial species such as spot prawns and sole cannot survive in low oxygen, however, said Tunnicliffe, who spoke at a symposium of international researchers meeting at the Institute of Ocean Sciences.

The group will decide today whether to adopt Saanich Inlet as the model for studying effects of oxygen-minimum zones.

"Saanich Inlet is a naturally low-oxygen system, with many of the features found in growing dead zones," Tunnicliffe said.

"What we're trying to do is get together a group of researchers to look at all aspects of the system and the goal is to become predictive. What happens in vulnerable areas, such as the St. Lawrence Estuary, which is starting to go hypoxic?"

Research into what happens when life-saving shots of cold, oxygenated water no longer wash into areas such as Saanich Inlet because of the warming top layer of the ocean should form the basis of ocean management and policy, Tunnicliffe said.

Managing change means addressing climate change and the amount of carbon dioxide going into the ocean and atmosphere. "Everything needs to breathe - you can't have systems suffocating," Tunnicliffe said.

Change is apparent in Saanich Inlet, said Frank Whitney of the Institute of Ocean Sciences, who has records dating back 50 years showing progressive warming and decreasing oxygen.

Steve Hallam, Canada research chair of environmental genomics at the University of B.C., said a conservative estimate is that seven per cent of the world's oceans are now low-oxygen areas.

"It doesn't matter where you go, the temperature is increasing and oxygen decreasing," he said.

Saanich Inlet is a model ecosystem because circulation is restricted in the 24-kilometre fjord, which has a 75-metre sill at the entrance. Each summer, it develops an oxygen-depleted layer.

In those hypoxic layers, researchers have found some microbes are thriving. "They don't breathe oxygen - they breathe alternatives like nitrate," Hallam said.

The microbes suck up toxic sulfides and carbon dioxide, which is a mixed blessing, since they then give off nitrous oxide, a greenhouse gas that's far more potent than carbon dioxide.

"There's a shift from things we can see to things we can't see and they're breathing different substances," Hallam said.

Information from Saanich Inlet is already being compared with low-oxygen areas elsewhere in the world, said Philippe Tortell, UBC associate professor.

"We are developing a collaboration with the Chileans to make comparisons between what happens in our local waters and what happens south of the Equator."

jlavoie@timescolonist.com

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