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  Kaleo.org 3 Aug 06
Professor discovers whaling kills deep-sea life
By Ting-Cheng Wen, Ka Leo Contributing Writer

At a symposium in Southampton, United Kingdom, a University of Hawai‘i at Manoa oceanography researcher recently presented his finding that whaling can cause the extinction of newly discovered species dependent on the energy-rich carcasses of whales for survival. Dr. Craig Smith and his colleagues discovered that when the bodies of dead whales sink to the sea floor, communities of deep-sea species live and feed directly on them.

“By studying the communities of animals colonizing dead whales implanted on the seafloor, we have found that there is a diverse community of animals that live in this habitat. Many are newly discovered species, occur in abundance on whale falls and have never been found anywhere else,” said Smith, a professor and the chair of Biological Oceanography at UH Department of Oceanography.

“Whale falls” are the bodies of dead whales after they have sunk to the deep sea floor.

Smith said that whaling has been creating a drastic decrease in whale populations, which also reduced the number of whale-fall habitats.

According to Smith, dead whales are a major source of organic and sulfide-rich habitat islands at the deep-sea floor. “Habitat loss is the major cause of species extinctions on earth, so dramatic loss of whale-fall habitats from whaling is very likely to cause extinctions of whale-fall specialists,” Smith said.

Whale-fall specialists are marine organisms who need whale-fall environments to sustain their population and to avoid extinction.

After a recent research project, Smith and his colleagues have concluded there are at least 37 species — up from the thought 28 — that could be whale-fall specialists.

Smith said research began as a coincidence. “We started the research by accident when we found a whale skeleton in the bottom of the ocean and saw that it was covered with very bizarre animals,” Smith said.

Through their studies Smith and his colleagues found that intense extinctions of whale-fall specialists are possible in the North Atlantic, where a large number of whales were eradicated from over-whaling in the 1800s.

Smith commented that extinctions “may be ongoing in the Southern Ocean and northeast Pacific, where intense whaling occurred into 1960s and 1970s.”

By demonstrating potential human impacts on the deep ocean, Smith believes that his findings illustrate a remarkably close association between ocean ecosystems and human activities.

“If we over-fish the ocean, we are likely to have impacted the deep sea floor. Whaling might cause species-extinction in the deep sea. And that the resumption of whaling could lead to extinction,” said Smith.

Smith’s whale-sinking experiments show that whale falls provide several successions of communities, one after another.

First, the mobile scavengers, such as sharks, eat the flesh of the dead whales, thereby removing the soft tissue. The remainder of the whale-fall is bones.

Second, the enrichment opportunists, such as worms and crabs, land on the bones and live and reproduce there.

“When we pick things off the bones of whales, we identify them,” said Iris Altamira, the chief technician of Smith’s Marine Benthic Ecology Lab, “Most of the species are smaller than the eyelash. The largest is about an inch long.”

Smith and professor James B. Nation of the UH Manoa mathematics department applied mathematical models to explore the impact of whaling on the extinction of whale-fall specialists. Nation said they also studied how factors, such as the availability of food and habitats, influence the population of whale-fall specialists with similar modeling.

At the 11th International Deep-Sea Biology Symposium in the U.K., Smith talked about how the organic-rich dead whales have specialized habitats. He also spoke of the recently completed modeling studies regarding the impact of whaling on the whale’s surroundings.

The conference in mid-July included more than 300 deep-sea scientists from 27 countries talking about their recent findings on how humans are impacting the deep sea.

“I thought there was a lot of exciting research going on, and one of the interesting conclusions from the conference was that it was amazing how much humans are impacting the deep sea,” Smith said.

Smith is planning more whale-fall research. He also wishes to know more about the whale-fall specialists and conduct experiments to find whether there is more evidence that would provide a clear illustration of the impact of whaling on the apparent whale-fall specialists.

“We want to get a better understanding of the global distribution of whale-fall specialists. We are planning on doing whale-fall experiments in a variety of different oceans to see whether the diversity of the whale-fall specialists matches the pattern of whales’ depletion,” Smith said. Smith is currently in Washington, planning for future whale-fall experiments.
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