Off the southern coast of Tasmania lies an underwater range of mountains home to a plethora of mysterious deep-sea creatures previously made vulnerable by bottom fishing. After having been protected for the last 20 years, many of these marine animals are making a comeback and, naturally, scientists are apt to study them.
As part of a four-week survey of the deep-sea ecosystem, researchers have found new areas of unmapped deep-sea coral and discovered more than 100 unnamed species of lobsters, corals, and mollusks.
“We ‘flew’ our high-tech camera system two meters above the seafloor in depths to 1,900 meters [6,200], collecting 60,000 stereo images and some 300 hours of video for analysis,” said voyage chief scientist Alan Williams in a statement. “While it will take months to fully analyze the coral distributions, we have already seen healthy deep-sea coral communities on many smaller seafloor hills and raised ridges away from the seamounts, to depths of 1450 meters [4,700].”
Williams said his team's findings indicate there is more of this important coral reef living in the marine parks than previously believed. A camera connected to a submersible allowed scientists aboard the research vessel Investigator to view in real-time the hundreds of other animals found, including feathery soft corals and tulip-shaped glass sponges in colors ranging from delicate creams to striking purple and bright gold. Notably, researchers recorded mutually beneficial relationships between many of the specimens collected, particularly among invertebrates and coral; brittle stars were seen curling around the coral while worms tunneled inside it. Also spotted were bioluminescent squids, ghost sharks, and basketwork eels near the seafloor.
“We now have a huge body of data on the animals that live on seamounts and how their communities change with depth, and have a much broader picture of what lives on habitats adjacent to the seamounts,” Williams said, adding that his team has now identified the precise depth range in which diverse deep-sea coral thrive. “On the larger seamounts, which peak in 1,000 to 1,250 meters [3,280-4,100] below the sea surface, corals dominate the top 100 to 200 meters.”
Though individual species of coral, feather stars, and urchins were observed re-establishing a presence in the marine parks, there is no evidence to suggest the coral communities are recovering. Deep-sea coral are different from their shallow cousins – fragile and slow-growing, these species prefer living in a cold environment void of sunlight or symbiotic algae.