Photo via Wikimedia
Ocean "dead zones" have been a mystery for scientists to understand. Their new tool in trying? Dead pigs. Scientists are "piggybacking" on forensics research to study oxygen-poor zones in oceans, with pigs as the animal of choice because of what turns out to be remarkable similarities between pig and human anatomy. Their skin is almost hairless, their bodies similar in size, and apparently their flesh has similar composition.So scientists are taking pigs from the butcher—no word on how picky they are about the pigs being raised sustainably—placing them in oxygen-poor zones, and using observations to extrapolate what happens to human bodies when they end up in the ocean. Using cameras operated from the shore, experiments off the coast of British Columbia have shown that marine animals would go to much oxygen-poorer conditions than the scientists expected—and they don't waste any time in doing so.
"We could put the pigs down and observe the scavengers as they arrived," explains Professor Tunnicliffe. "On day one, we lowered the pig," she says. "By day two, we've had crabs and shrimp, then octopus. Then sea stars arrive. They've had to travel across the bottom. They know something's there and they arrive almost immediately and stay there." At levels down to almost 7% oxygen in the water - well below what scientists predicted would be tolerable - the animals still coped.
That was a surprise, given the need all marine animals have for oxygen in their blood; hypoxia, the name for a severe oxygen shortage in the body, is a deadly condition. There was a limit, though, to how far these animals would go for food. The third pig in the trial was not touched by a single animal for three months.
The oxygen there was below that severe level, so even these hardy scavengers had reached their limit. "That means nothing's getting recycled on the seafloor. It's just stuff lying there waiting for bacteria to do a very slow decomposition," says Professor Tunnicliffe.
"These scavengers get the carbon cycle back. We have to get the nutrients back in the system and start this restoration process." She says that this provides insight into how marine ecosystems can recover from hypoxia - and that it gives scientists some hope.
Dr. Verena Tunnicliffe, who is a professor of marine biology at the University of Victoria in Canada, elaborated on the significance of these findings: The dead zones are occurring from the bottom of the ocean and spreading upward, pushing animals up with them from the sea floor. "If some of these animals can survive, with a little bit of oxygen coming in, perhaps they can get down there and start that clean-up."