An Army of Animal Oceanographers

Several years ago, a colleague came into Dave Foley’s office at the National Oceanic and Atmospheric Administration in Pacific Grove, Calif. and asked if there had been a storm at a spot in the middle of the Pacific Ocean at a certain time a few days earlier. Foley raised his eyebrows a bit, but looked up the weather data and found that there had indeed been a storm.

The colleague called back later that day and asked if the storm had stopped at a specific date and time. Eyebrows now leaping off his head, Foley looked again, and sure enough, the storm had ended at the suggested time. How did his colleague know? By watching the dive behavior of a sea turtle.

Researchers have used tracking devices on many species of wildlife for years to learn about the animals themselves, including information about their habitats, breeding patterns and migration. It is a much newer idea, however, to use animal tracking to collect data about the environment in which the animals live. “Animals take some measurements far better than we can on a ship,” said Foley, coordinator of NOAA’s satellite oceanographic information processing program, CoastWatch.

A study published in the August 19 issue of Proceedings of the National Academy of Sciences provides the latest example of this method, in which tagged elephant seals were able to fill in crucial blank spots in oceanographic and ice formation data in the Southern Ocean around Antarctica.

The seals’ behavior makes them excellent data collectors. “Elephant seals forage over large regions covering lots of ground, and at least once a week you can expect a dive down to 1,000 meters,” said Daniel Costa, an evolutionary biologist and ecologist at the University of California, Santa Cruz and an author on the study. “You can do a lot from ships, but they are extremely expensive and can’t go to a lot of places. The end result is that we have very little data.”

Fifty-eight seals fixed that problem, providing a more complete view of ocean front structure and ice formation around Antarctica. The seals collected 8,200 profiles of temperature and salinity, from which scientists can infer ice formation, in the remote southern seas from 2004 through 2005. The result was more than nine times the information acquired from floating buoys and ships in that region combined.

Even more striking were the 4,520 profiles seals provided from within the sea ice zone near Antarctica, a 30-fold increase over the data from ships and buoys. The ice formation rates measured by the elephant seals matched those determined by mathematical modeling, supporting the reliability of the animal-collected data.

Given the success of the elephant seals, might other animals yield similarly useful data on their natural habitats? “You pick up the animal that’s appropriate for the question,” said Costa. He said tracking is being done on California sea lions, Weddell seals, penguins, beluga whales, some types of sharks and other fish. Hooded seals have also proven effective at data collection around the Arctic, as they travel back and forth between Norway and Greenland often. “It’s almost like they were designed to do oceanography,” Costa said. He added that animal data collection also has the benefit of being more cost-effective than ship expeditions.