Seamounts may serve as refuges for deep-sea animals

Washington, Feb 12 (ANI): New findings indicate that seamounts may serve as refuges for deep-sea animals that struggle to survive elsewhere.

Over the last two decades, marine biologists have discovered lush forests of deep-sea corals and sponges growing on seamounts (underwater mountains) offshore of the California coast.

It has generally been assumed that many of these animals live only on seamounts, and are found nowhere else.

However, two new research papers show that most seamount animals can also be found in other deep-sea areas.

Seamounts, however, do support particularly large, dense clusters of these animals. These findings may help coastal managers protect seamounts from damage by human activities.

Tens of thousands of seamounts dot the world's ocean basins. Although some shallower seamounts have been used as fishing grounds, few seamounts have been studied in detail.

Davidson Seamount, about 120 kilometers (75 miles) offshore of the Big Sur coast, is an exception. Since 2000, researchers have spent over 200 hours exploring its slopes and peaks using the remotely operated vehicle (ROV) Tiburon.

Following each expedition to Davidson Seamount, marine biologists at MBARI studied high-resolution video taken by the ROV and identified every animal they could see.

Over 60,000 of these observations were entered in MBARI's video annotation and reference system (VARS).

Craig McClain and Lonny Lundsten, the lead authors of the two recent papers, used the VARS database to find out which animals were unique to Davidson Seamount and which had been seen elsewhere.

Altogether, 168 different species of animals were observed on Davidson Seamount. McClain's search of the VARS database showed that 88 percent of these animals had also been seen or reported in other deep seafloor areas, such as the walls of Monterey Canyon.

Three quarters of the species on Davidson were not even unique to the California coast, and had been seen in seafloor areas over 1000 kilometers (620 miles) away, including the Hawaiian Islands, the Sea of Japan, and Antarctica.

Only about seven percent of the species at Davidson Seamount had never been seen anywhere else. Of these 12 apparently "endemic" species, most were new to science. lthough few animals are "endemic" to Davidson Seamount, the research demonstrated that this seamount does support distinctive groups of animals, which are dominated by extensive "forests" of large, "old-growth" corals and sponges.

According to Craig McClain, one of the lead authors, "The large groves of corals and sponges are unique to seamounts. The crests of seamounts are particularly good because they provide flat rocky surfaces that don't accumulate much sediment. This is partly due to the fact that seamounts are so far offshore." (ANI)