Leg Two, Open Ocean to Inner Sea

Finish Line

Mark Schrope
Sep. 19 2013

The expedition ended with a marathon dive through a portion of the Olympic Coast National Marine Sanctuary and the successful completion of a long day’s hunt.

Jackson Chu, directing a Tully Canyon dive.

The target was Tully Canyon, on the U.S. side of the borderline, and it’s considered an important pathway for lower oxygen water offshore to make its way inshore. As far as we know, the deeper reaches of this canyon—we were working down to about 300 meters—have never been seen before.

The team had to apply for special permissions to work in Tully because of its sanctuary status, and we weren’t allowed to collect any samples. We were only allowed to dive beginning at midnight this morning, so the team launched the ROV right after that and stayed down until midday. Then, after a quick move to another site, ROPOS was down until about 9pm.

A sea star and urchins at Tully Canyon.
A sea star and urchins at Tully Canyon.CSSF/ONC/SOI

One striking feature of the canyon was the lingering signs of past commercial trawling. Past trawl scars can be visible for years. Each shows up as a dark line on the ROV’s sonar (see image at right) because of the indentation the trawling gear leaves behind.

Another standout event came early on, when the cameras revealed the skeletal remains of a mammal of some sort, possibly a seal, with urchins and other animals gathered around still taking advantage of this rare food source.

The Hunt

A sample ROPOS sonar view with the signs of past trawling activity showing up as dark lines.
A sample ROPOS sonar view with the signs of past trawling activity showing up as dark lines.CSSF/ONC/SOI

Jackson Chu led this dive and his main goal was to find very low-oxygen water. He was seeking an area to compare against Saanich Inlet, with its near zero oxygen and unique assemblage of low-oxygen tolerant animals. But for hours and hours on, while criss crossing various parts of the canyon, he had been unable to find oxygen levels any lower than other areas where we’ve been working.

Then finally, after almost a whole day exploring underwater, the sensors on ROPOS finally revealed very low oxygen levels–to Jackson’s joy and relief. So Jackson worked with Keith Shepherd to maximize the ground they could cover within this sought after zone. “It was literally a race to the finish,” says Jackson. Keith had to modify dive plans to squeeze in a few more minutes on the bottom, allowing Jackson to just barely complete the transect he needed for his research.

Jackson spotted a number of similarities to the Saanich community, including a lower diversity of life and the presence of the slender sole, the same species he had been studying at Saanich. Incidentally, the fish the ROPOS team caught, nicknamed Vinnie Jr., is alive and well back in the laboratory on shore.

Obligatory closing sunset view.
Obligatory closing sunset view.Mark Schrope

As the long dive day was wrapping up, everybody who could retired to the upper deck for the traditional end of cruise barbecue—this one American style in honor of our brief dip below the Canada-U.S. border.

After ROPOS was on deck, we began making our way back to Victoria. A successful cruise means a great deal of work for all involved back on shore. In the case of the science team, there are countless hours of video surveys to analyze, and samples to process.

Over time, the team will be able to put together the first clear picture of life in Barkley and Tully Canyons, which will lend vital context to the work on the NEPTUNE observatory with all its ability to gather non-stop data on the region.

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