A front-page article written by SFI Omidyar Fellow Nathan Collins describes researchers' work to quantify, for the first time, the complex interactions among humans and other species in the food webs people are a part of.

The piece is the second in a series written by SFI scientists, called "Science in a Complex World," to be published once a month in the Santa Fe New Mexican.

"Using data collected through interviews, studying archaeological sites, and observing wild plants and animals, [SFI Professor Jennifer Dunne and a team of archeologists and ecologists are] reconstructing the entire ecosystem of Sanak Island [Alaska] over the last 5,000 years, including how people have fit in to that ecosystem, and they're starting to get clues about how the people there minimized their negative impact on the natural environment.

"One of the most important Sanak Aleut habits is switching it up, just like other predators do. When the salmon population got low, they hunted for sea lions, and the reason is simple -- salmon were harder to find. Switching what they ate every so often had a profound effect. By eating less of the harder-to-find plants and animals, those things had time to recover, so no population ever got too low. In other words, mixing it up meant the ecosystem always stayed healthy.

"These days, Dunne says, there's a different reason people hunt: money. Bluefin tuna were recently in the news because, as their supplies run low, fishermen can make more money hunting them, driving their numbers ever lower. But it's worse than that. Because of the complex relationships in food webs, depleting one animal might cause ripple effects that could devastate entire ecosystems. For example, scientists know that sea otters eat sea urchins, and sea urchins eat kelp, so that by eating sea urchins, sea otters helped keep the kelp population afloat. The sea otter population in the Pacific Northwest, however, is in decline -- possibly because orcas are eating them in increasing numbers -- leading indirectly to kelp deforestation, which in turn hurts scores of creatures like snails, fish and even humans that eat kelp or live in kelp forests."

Read the full article in the Santa Fe New Mexican (February 28, 2011)