Warmest summer ocean temperatures recorded off Vancouver Island coast

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A Victoria-based marine research group has recorded the highest daily average summertime temperatures at two of its sea floor observatory sites in the northeast Pacific Ocean since continuous monitoring began in 2009.

And while it’s not known exactly why the temperatures have climbed, researchers say the record-setting readings highlight the importance of monitoring ocean conditions.

Unlike satellite measurements that track sea surface temperatures that can signal marine heat waves, the sensors and equipment used by Ocean Networks Canada record temperatures at varying depths of the ocean, providing a window into changing conditions on the ocean floor.

“What we are seeing here is beneath the surface,” said Kate Moran, president and chief executive officer of Ocean Networks Canada, which announced the findings Friday.

“There are increases in temperature – in one location, 400 metres beneath the surface – which you can’t measure with satellites. So we’re seeing changes in the deeper part of the ocean that are quite concerning.”

A University of Victoria initiative, Ocean Networks Canada operates observatories that comprise ocean and land sites on the Pacific, Atlantic and Arctic coasts of Canada. One of those observatories, dubbed the North-East Pacific Time-Series Undersea Networked Experiments, or NEPTUNE, is an 800-kilometre cable-connected system located off the west coast of Vancouver Island.

On Friday, ONC announced temperature records for two sites on its NEPTUNE system. On Aug. 10, a new daily average temperature high of 8.57 C was reached at Folger Deep, compared to the previous 14-year record for that date of 8.44. On the same day at Barkley Upper Slope, a new record of 6.01 was reached, compared to the previous high of 5.90 on that date.

Both sites are on the continental shelf of the northeast Pacific Ocean, with Folger Deep at about 95 metres beneath the surface and Barkley Upper Slope site about 400 metres beneath the surface.

ONC researchers said several possible factors could be causing warmer summer waters, including excess heat from climate change, changes in wind patterns and changes in how deeper waters are moving around the ocean.

The Barkley site is located in a type of ocean canyon that serves as a conduit for water to move from the coastline into the deep ocean or from the deep ocean to the coastline, depending on the time of year, Dr. Moran explained.

Because of its depth, it’s considered less likely that temperature increases at that site can be directly linked to the kind of blazing-hot weather that resulted in B.C.’s 2021 “heat dome” event, she said. So researchers will be trying to determine what could be affecting temperatures at that deeper site, including changes in what’s known as upwelling – a process in which colder water moves up toward the ocean surface.

“We’ll be investigating that, because we have a lot of other data we can look at,” Dr. Moran said.

Researchers will also be using cameras, sensors and equipment to track marine life in the context of changing temperatures, including fish and sea urchins, which previous ONC research has shown will move when ocean oxygen levels decline.

So far, ONC has not detected changes in oxygen levels, but they will be monitored as part of the group’s activities.

Founded in 2007, ONC got a significant boost last year with nearly $115-million in federal funding – money that Dr. Moran said will help expand and refine the network and its projects. They include early warning systems for earthquakes and tsunamis, and research into using ocean processes to remove carbon dioxide from the atmosphere.