Sharks fitted with cameras help uncover ocean secret

Gliding through the clear waters of the Bahamas the tiger shark spots a large tropical fish hovering above a patch of green seagrass.

The shark makes its way over to potential prey before it turns, continuing its journey through the swaying vegetation.

The shark, filmed in incredible detail, is one of seven mature tiger sharks involved in a ground-breaking marine study, today published in Nature Communications.

Researchers mounted revolutionary 360-degree cameras on the apex predators and in “partnership” with the creatures mapped what’s believed to be the world’s largest seagrass system in Bahama Banks.

The cameras provided researches with a shark's eye view of the ocean floor. — The cameras provided researches with a shark’s eye view of the ocean floor. (Beneath the Waves)

Dr Oliver Shipley, a senior research scientist with Beneath the Waves, told 9news.com.au the study could change how the ocean is surveyed.

He forecasted that other species could soon be used to map the mysteries of the deep.

“Over the next five to 10 years we will see a real kind of uptake in partnering with animals to uncover their secret lives, and survey and explore parts of the ocean we couldn’t,” Shipley said.

“People are using turtles, they are another great animal … and we are actively working with ocean sunfish, or mola mola, which is another animal we know little about, but moves expansive distances in the ocean.”

The cameras are mounted using biodegradable zip ties that break down, allowing the package to rise to the surface.

“Nothing remains on the animal once the tag comes off,” he said.

The scientists deployed bio-logger tags equipped with cameras on tiger sharks. Review of this footage showed significant time spent in seagrass habitat, and sparked the initial curiosity around the seagrass meadows of The Bahamas. (Diego Camejo for Beneath The Waves)

Shipley said the ideal animal candidate should spend a lot of time towards the bottom of the ocean.

This is one of the factors that makes tiger sharks ideal surveyors.

“They also move considerable distances – up to dozens of kilometres each day,” Shipley said.

“We ‘partnered’ with the sharks to perform one of the largest and robust seagrass surveys to date.”

The seagrass mapped by the sharks covers 66,000 square kilometres, potentially up to 92,000.

If this assessment proves correct it would make it the biggest seagrass system in the world; larger than the 40,000 square kilometre system off the coast of Queensland, and representing an increase in the global seagrass estimate by up to 41 per cent.

Dr Austin Gallagher surveys the Bahamas Bank seagrass meadow with SeaLegacy co-founders Cristina Mittermeier and Paul Nicklen. (Cristina Mittermeier / SeaLegacy)

Seagrass meadows are more than just blue carbon sinks, and act as feeding and nursery grounds for an abundance of marine life–such as elasmobranchs like sharks and rays, and economically and culturally significant species like Queen Conch. (Cristina Mittermeier)

Shipley said ”there’s a couple of important implications” behind the discovery, explaining seagrass helps to mitigate the impacts of climate change.

“If you have a large seagrass system off the coast of a low-lying country like the Bahamas it actually helps buffer some of the storms,” he said.

“They also absorb an awful lot of CO2 (carbon dioxide).

“When we think about trying to find natural solutions to mitigate the effects of climate change, a seagrass ecosystem is about as good as you can get.”