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April 28 (UPI) -- By analyzing the feeding patterns of crabeater seals, scientists have designed new models to predict the effects of environmental changes on Antarctic krill distribution. "We're using the feeding behavior of this one predator as an indicator of the habitat for their prey and how that could change," Luis Huckstadt, researcher with the Institute of Marine Sciences at the University of California, Santa Cruz, said in a news release.
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For the last several years, Daniel Costa, professor of ecology and evolutionary biology and director of the IMS, has been using electronic tags to track the movements and behavior of crabeater seals, as well as collect environmental data related to their habitat preferences.
Because crabeater seals stay close to the ocean surface when traveling and only dive when feedings, tracking data can be used to determine the location of large Antarctic krill populations. Scientists were able to use the the environmental data collected by Costa and his colleagues to estimate the kinds of marine conditions preferred by the tiny crustaceans.
Researchers used the data to build a model capable of simulating the effects of climate change on the krill distribution along the western Antarctic Peninsula. The published the results of their modeling efforts this week in the journal Nature Climate Change.
As the climate warms, krill numbers are likely to decline along the northern portions of the peninsula. As water temperatures rise and currents shift, the crustaceans will move farther offshore.
Along the southern part of the peninsula, south of Alexander Island and in the Bellinghausen Sea, krill distribution is likely to expand. Both seals and the many other predators that rely on krill will have to adapt their foraging patterns and follow the krill southward -- or find new sources of food.
"The shift in krill habitat away from coastal waters in the north has big implications for species like penguins and fur seals, which can't make long foraging trips because they have to come back to land to feed their offspring," Huckstadt said.
Because crabeater seals spend all year in Antarctica and don't live in small, flexible groups instead of massive colonies, scientists expect the marine mammals will be better able to adapt. Other marine species that migrate to the region each summer, like humpback and minke whales, will have to make longer treks to find food.
"It will be challenging for a lot of species," Huckstadt said. "Things are changing so fast in Antarctica, the changes we're seeing in our model might be coming sooner than we expected."
Marine mammals are the only animals that hunt krill. Humans use krill for aquaculture feed and fish bait, and the Antarctica Peninsula is home to largest krill fishery in the world.
"We don't really have a good grasp on how fishing pressure will change in the future, and that's one reason so many marine protected areas have been proposed for the western Antarctic Peninsula," Huckstadt said. "The peninsula is critical habitat for krill, which is the most abundant and important prey species in this region. Everything depends on krill, so any changes will cascade through the ecosystem."
