Deep sea mapping advances understanding of coral

Ocean Sciences Centre seminar series raises important points on coral research and conservation

By Marie King

Researchers are using sound to map the ocean floor, says Craig Brown.

Brown, a marine ecosystems researcher, and professor Sue Gass presented a lecture on seafloor mapping technologies that aid in studying cold-water coral (Lophelia) habitats at MUN on Jan. 22.

He took the podium first and explained the use of sound rather rather than light as a tool for scanning the seafloor in deep waters. Acoustic techniques, such as multi-beam sonar, were difficult to access due to cost as recently as 10 years ago, but are widely used today in studying deep water substrates.

The multi-beam sonar device sends out over 100 beams at a time, measuring the intensity of the sound waves reflected back to the vessel.

“By measuring the intensity of sound waves from the seafloor, we can learn some of its characteristics,” said Brown, who works for the Department of Fisheries and Oceans Canada.

These characteristics are important in understanding the coral itself. Research on coral habitats helps prioritize which areas should be protected as conservation areas, the researchers said.

Brown and Gass — an environmental science professor at Dalhousie — spoke of the mapping European seabed habitats (MESH) project and showed a short video clip (www.searchmesh.net) displaying the coral and the valuable habitat they provide for various invertebrate and vertebrate species.

They explained that, cold-water coral reef grows at the ends. The inner reef structure dies off, but the dead structure provides a habitat for many species, including new coral growth.

One of the areas Gass has focused on, the basis for her PhD research, was in the North Sea, east of Scotland. Advances in mapping technologies allowed the discovery of cold-water corals growing around the bases of oil platforms, an unlikely habitat for the corals.

Before oil platforms were introduced in the North Sea in the ‘70s, there were no records of the presence of Lophelia. Using the multi-beam sonar, scientists found that the seafloor in this area was soft and sandy, not an appropriate substrate to provide habitat for the corals.

However, the oil platforms provided the hard substrate necessary, and natural colonies to the west of Scotland provided inflow of larvae to the area.

Another case study presented natural coral colonies near Mingulay, east of Scotland. “Before the project the only evidence of coral was from fishing,” said Brown.

The research revealed that the coral near Mingulay actually spans seven kilometres across, with some reaching 10 metres in height. Gass, who spent a lot of time studying coral near Mingulay, said, “We were out every day, for better or for worse, seasickness or not.”

They have also researched Lophelia in Atlantic Canada, leading to the designation of protected areas such as the Northeast Channel south of Nova Scotia.

The protection of the corals was brought up in the question period at the end of the lecture. Gass said it is important not only for the species of coral, but also extremely important because the coral acts as a habitat for different organisms.

Damage of corals occurs due to fishing, searching for new oil reserves, and other human activities in the deep seas. Corals take years to recover from this damage.

The lecture was part of a weekly seminar series sponsored by the Ocean Sciences Centre where experts speak on a wide range of biology-related topics.

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