First published in Landings, September, 2015.
When you hear the word “coral” you typically think of shallow, clear turquoise water and colorful reefs populated by bright tropical fish. In the Gulf of Maine, however, lie spectacular cold water coral formations that are just now being mapped and explored. Cold water coral communities are unusual because they are so slow growing and appear to be vital to the biodiversity of the Gulf of Maine.
Deepwater corals are not new to fishermen. In fact, fishermen called them to the attention of biologists over a century ago. Trawler captains were familiar with “the trees,” coral formations found on Georges Bank and the Scotian Shelf. Most corals lie in the very deep submarine canyons and seamounts far out along the edge of the continental shelf. However, they also occur in deep areas within the Gulf, such as Jordan Basin. Principally these are soft corals with flexible skeletons, unlike the species that build reefs. Because it takes so long for the corals to grow, some large colonies may be hundreds to over a thousand years old.
Since 2013 scientists funded through NOAA’s Deep Sea Coral Research and Technology Program have been using remotely controlled underwater vehicles and multibeam sonar during research cruises to identify coral communities in the Gulf. This year during a ten-day research cruise aboard the RV Connecticut, scientists from the University of Maine, the Northeast Fisheries Science Center, and the Northeast Underwater Research, Technology and Education Center at the University of Connecticut surveyed three areas: Outer Schoodic Ridge, the Mount Desert Rock area and the Georges Basin region.
One site on Outer Schoodic Ridge that was revisited showed dense coral and sponges along the bottom and on the steep vertical walls. Scientists also observed a tremendous number of haddock moving through the coral. In previous years large schools of pollock and silver hake had been seen in the same place. Two dense coral walls were discovered in the Mount Desert Rock area this summer, full of red tree coral, fan coral and multiple species of sponge.
No corals were observed, however, at the few locations visited at the base of the slope stretching from Georges Bank into Georges Basin. “Lindenkohl Knoll at the northern boundary to Georges Basin did have sparse corals in multiple locations along with evidence of extensive impacts from fishing,” said Peter Auster, a Research Professor Emeritus at the University of Connecticut and Senior Research Scientist at Mystic Aquarium, who took part in the cruise. Steep vertical rock outcrops, like those in the northern Gulf that supported dense coral gardens, showed marks from fishing gear and were nearly stripped of all life.
“The fact that we found these spectacular walls of corals for the first time in 2014, and at additional sites in 2015, after 40 plus years of research with submersible vehicles in the Gulf of Maine illustrates how much more we need to understand about the Gulf ecosystem in order to better conserve and manage our natural resources,” Auster added.
In a report to the New England Fisheries Management Council (NEFMC) in December, 2014, the scientists involved in deep coral research noted the role deep sea corals play in providing habitat for numerous marine species. Pandalid shrimp, amphipods, and schools of krill were commonly associated with coral communities along steep walls. Acadian redfish used coral for shelter whereas Atlantic cod, cusk, goosefish, pollock, silver hake and spiny dogfish were observed searching for and catching prey amid the coral colonies.
The fragility of deep sea corals and their value to commercial species of fish led the Mid-Atlantic Fishery Management Council in June to restrict fishing activities over an area of deep ocean bottom stretching from Long Island to Virginia, principally in areas deeper than 450 meters and out to the seaward edge of the Exclusive Economic Zone. If approved by NMFS, the council’s proposal would create the largest area protected from bottom fishing in U.S. Atlantic waters, about the size of Maryland, Delaware and New Jersey combined.
In New England, the NEFMC is not developing a specific plan for deep sea coral protection. Rather, it is working to develop an omnibus amendment, like the one recently approved for essential fish habitat, to amend existing fishery management plans to designate coral management areas, according to Michelle Bachman, Essential Fish Habitat Omnibus Amendment coordinator at NEFMC. “If these corals are destroyed, they are not coming back in any ecologically significant period of time,” Auster said.Category: Science