 Prenatal Care In Ocean Depths
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Sept. 16, 2003 — Deep-sea explorers have discovered an unprecedented "hot-spot" nursery of rare fish and octopuses off the coast of Northern California.
Octopus, normally solitary, and extremely elusive fish called the blob sculpin have been found by the dozens brooding hundreds of eggs on the rocky outcrops along what's called the Gorda Escarpment, a mile underwater.
"We have never seen prenatal care in deep-sea organisms before," said Jeffery Drazen of the Monterey Bay Aquarium Research Institute. "That makes it quite interesting."
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Drazen and colleagues Shana Goffredi, Brian Schlining and Debra Stakes reported the discovery at the recent Deep Sea Symposium at Coos Bay, Oregon and in the current issue of Biological Bulletin.
Particularly intriguing are the two-foot-long blob sculpin, which were first discovered 30 years ago and have rarely been seen since — and certainly never in groups guarding eggs, said ichthyologist Greg Caillet of the Moss Landing Marine Laboratory. "It's a pretty special spot," Caillet added.
Eighty-four blob sculpin were spotted on exploratory Remotely Operated Vehicle (ROV) dives in 2000 and 2001, along with 64 nesting sites with eggs.
What exactly makes the spot on the Gorda Escarpment so special is still a mystery, Drazen said. About the only thing biologists are certain of is that both the octopuses and sculpins prefer the rocky areas because they can stick their eggs to rocks and they'll stay put. But there are plenty of rocky areas without brooding sites, Drazen said, so something else must be going on.
One possibility is that the blob sculpin takes advantage of the steady current along the ridge of the escarpment to supply oxygen to their eggs. That could be saving the parent fish the trouble of fanning the eggs. As for octopuses, they might prefer the area because it's close to spots where cold, nutrient-rich water seeps up from the ocean bottom. The nutrients probably support clams and other marine life, Drazen added, providing a veritable all-night diner for octopuses.
"We may never know," said Caillet of the precise reason for the crowding of fish and octopuses. It could, after all, be a combination of subtle features, preferences or habits that only a sculpin or an octopus can understand.
Regardless of the cause, however, the discovery of the deep-sea nursery is providing marine biologists with another example of how the ocean bottoms are not just vast, dull places where nothing ever happens, Drazen said.
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