SeaCycler passes tests in Halifax before open ocean deployment

Scientists from the Bedford Institute of Oceanography and Dalhousie University are breathing a little easier.

This week they successfully deployed, tested and retrievedan advanced ocean sensor prototype called the SeaCycler in Halifax's Bedford Basin.

The sea trial was a last chance to "test drive" the SeaCycler before it is taken to the Labrador Sea next month for a critical one-year deployment in the North Atlantic, says BIO engineer Greg Siddall.

"We are preparing for the big deployment. We needed to make sure everything was working and we put it through its paces. It performed very well. We are very happy," he said.

How the SeaCycler works

Engineers have mounted 11 sensors on board the SeaCycler tomeasureoxygen, carbon dioxide, light, nutrients, salinity and temperature.

The device is moored to the ocean floor and rests 150 metres below the ocean surface, safe from hazards like waves, icebergs, ships and nets.

When commanded, the sensor float rises through the water and makesmeasurements as it goes.

Once on the surface, a small antenna transmits data to a satellite. SeaCycler is expected to transmit every 20 hours for an entire year.

Three onboard computers control the winch, data handling and transmissions from the surface. Scientists on land also have the ability to issue commands on what data is collected and how much is sent.

"This is brand new oceanographic technology," Siddall said.

Big stakes

The Bedford Basin sea trial was the 13th deployment, and it has now spent 663 days under water.While the SeaCycler is a marvel of engineering, one year in the North Atlantic may be its toughest challenge yet.

This will be a return trip to the Labrador Sea.The first deployment there failed on launch in September 2015.

That disappointment raised the stakes for the international team behind the project, which also includes the Scripps Institution for Oceanography, an advanced research facility associated with the University of California and the German government.

Disaster strikes

The setback occurred just minutes into the planned year-long deployment in the Labrador Sea.

Shortly after it was lowered from the back of German research vessel Maria S. Merian, a portion of the 3,500-metre long mooring cable snagged and then snapped, leavinghalf a million dollars of sensorsand equipment adrift in the North Atlantic.

The mishap was not discovered for many hours.

The Merian burned tens of thousands of dollars worth of fuel and 24 hours of sea time to steam back and retrieve the SeaCycler, which was able to signal its location through a beacon.

"We are very grateful to the Germans for what they did for us," Siddall said.

The cable that failed has now been replaced with a much stronger and stiffer design, and potential chafe points have been removed by adding fairings to streamline the device.

That's ocean science

Richard Davis, from the Ocean Tracking Network based at Dalhousie University, says that's ocean science for you.

"It's not cheap and it's not easy. Any time you put something in the ocean you are taking your chances," he said.

SeaCycler, he says,is an example of international co-operation.

"If you can get a German boat to take a Canadian piece of equipment out, that saves money for everybody, it makes for a bigger pool," he said.

"We are always looking for chances to make the most of what we have so we can get as many observations as we can."

Why go to the Labrador Sea?

The Labrador Sea has been described as the "lungs of the ocean."

It is one of the few places in the world's oceans where the surface water becomes so dense it sinks, carrying oxygen and carbon dioxideinto the deep ocean where it is dispersed.

The gas transfer makes it a valuable place to study climate change and the SeaCycler a valuable tool.

It's trip to the Labrador Sea is part of a pan-Canadian initiative involving scientists from 11 universities and multiple federal government laboratories.

The goal is to understand how the deep ocean exchanges carbon dioxide, oxygenand heat with the atmosphere through the Labrador Sea.

With footage from Uwe HehlofLeibniz Institute for Baltic Sea Research, Warnemunde,and Jeremy Lai of Dalhousie University.