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This article was received by email from IFAW Australia 20th July 2006

Whaling seen as threat to scavengers


July 20, 2006


In 2004, marine biologists discovered two strange new worms 9,000 feet down at the bottom of Monterey Bay Canyon. They were bizarre for many reasons - they had no eyes, legs, mouths or stomachs - but also because they were, with the help of symbiotic bacteria, feasting off a dead gray whale.

The new worms, whose Latin name means "bone devourer," sport reddish feathery plumes that behave like gills. At the other end, the worm's body forms a large egg sac with greenish roots sprouting from it. The roots are filled with bacteria that break down the oil in whale bones.

Crab. photo by  Craig SmithCRAIG SMITH / University of Hawaii

A deep-sea stone crab lives on a blue whale bone on the ocean floor off the California coast.

Scientists at Monterey Bay Aquarium Research Institute were initially puzzled because all the collected worms were females. Under the microscope the mystery was solved: Inside the females were dozens of microscopic male worms. The males were undeveloped - their bodies still contained bits of yolk - but they were loaded with sperm.

The bone devourers take the weirdness prize but they are far from being unique in their food source. Craig Smith, a marine biologist at the University of Hawaii, has been visiting continental marine canyons off the California coast since the late 1970s and has identified entire ecosystems with hundreds of animals that live on dead whale carcasses. Some of these communities exist for decades, sustained on oil-saturated whale bones.

Now he's sounding the alarm that whaling continues to be a threat to these ecosystems. His research, based on models and reported last week at the Deep-Sea Biology Symposium in England, suggests that extinctions may have already occurred in the North Atlantic where 13 species of great whales were decimated in the 1800s. Extinction may also be ongoing in the Southern Ocean, where intense whaling persisted until the 1970s.

Evolving with whales

Whale carcasses - or whale falls - inject a massive amount of food into an otherwise nutritionally limited environment. One whale fall can provide up to 160 tons of organic material, as much as thousands of years of marine snow, the organic debris that drifts down from surface waters.

It's a buffet for uniquely adapted organisms. Whale falls support some of the same animals that inhabit hydrothermal vents and others found nowhere else. The bacteria found in the Monterey Bay worms are the only lipid-degrading symbiotic bacteria known. Researchers believe enzymes isolated from whale fall bacteria may some day be useful in industrial applications.

Whale fall communities may be ancient ecosystems. DNA data indicate the most recent common ancestor of the two Monterey Bay worm species lived roughly 42 million years ago, about the same time whales themselves first evolved. The worms' genetic diversity also suggests they are part of an actively breeding population that includes hundreds of thousands of individuals - a previously unimagined, teeming biodiversity.

But too much may be gone before it is even known, Smith lamented in his presentation last week. The 20-year global ban on whaling was threatened last month when the International Whaling Commission voted in support of the resumption of commercial whaling. Another vote, with 75 percent approval of members, is required to reverse the ban. Japan, Russia, Norway and Iceland continue to support resumed commercial whaling.

"The possibility that whaling has caused species extinctions at the remote deep-sea floor gives me new appreciation for the scale of human impacts on the ocean," Smith told the conference. "We need to recognize that the oceans consist of a stack of tightly connected ecosystems - overfishing in surface waters is bound to cause problems thousands of meters below."

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