Mapping out eelgrass in Sooke taken to new heights

Drones for mapping eelgrass

[Editor’s Note: Paul Hunter, University of Victoria’s operations manager of field work, shared that drones are the most cost-effective and efficient way of running an experiment of this scale.]

This post originally appeared on http://www.sookenewsmirror.com/news/384302291.html.

Passersby walking along Whiffin Spit on Wednesday morning noticed something different – an area tapered off with a group inside wearing high-visibility jackets huddled around a drone.

They weren’t yahoos testing out their new flying toys though, but University of Victoria graduate students preparing for an experiment that will identify how eelgrass has changed over time and attempt to find the drivers of those changes.

Heading the experiment is chief researcher Natasha Nahirnick, who is looking to map long-term eelgrass dynamics over time using archived aerial photography – an ideal job for an unmanned aerial vehicle (UAV) to do.

“We needed a spot that was fairly well sheltered from the waves, just because all our sites in the Gulf Islands are these sheltered little spots,” Nahirnick said, adding that Whiffin Spit was a suitable testing location out of controlled space to test out the UAV’s mapping abilities.

Why eelgrass?

Nahirnick said eelgrass is threatened due to increasing development on the coast, more boat traffic, as well as increased agricultural lands that put more nutrients into the stream systems that make their way into our coastal waters.

“All that can severely impact eel grass through epiphyte growth (algae that grow directly on the blades of eel grass) it will block all the light, so the eelgrass can’t photosynthesize,” she said.

Eelgrass is one of the main aquatic marine vegetation on the West Coast, second to kelp, and provide shelter for sea creatures such as salmon, who use patches of eelgrass for hiding their young from predators. Same goes for Dungeness crab, while herring will spawn directly on it.

Using aerial footage from 1930s archives of forests, roads, rivers and oceans, the team plan to take it to the next step using modern technology.

“We’ll use UAVs to do the surveys then map it from that aerial photography,” Nahirnick said.

Piloting the drone, a X650 Pro model built X Aircraft, is Paul Hunter, UVic’s operations manager of field work, who oversees the flight planning and overall conduction of the flight.

Hunter noted this is the most cost-effective and efficient way of running an experiment of this scale.

“This is more effective than doing it with GPS units in a kayak, and a traditional manned aircraft survey for an area as big as this in Sooke is a $6,000 flight,” he said.

Even the incoming wind at Whiffin Spit wasn’t enough to trouble the drone (affectionately named The Tick) which remained completely stable during all its flights.

For mapping and photography, the drone is fitted with gimbled GoPro that uses a special corrected rectolinear lens that doesn’t distort images, making it easy to stitch them together.

The lens also increases spacial resolution as it reduces field of view from 170 degrees to about 55 degrees, allowing for sharp zoomed views.

Working with Sea Change, the Main Island Conservancy, the Saturna Island Marine Research and Education Society, the research team hope to start mapping and getting a better look at eelgrass in one of B.C.’s busiest coastal waterways.

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