Wednesday, February 6, 2013

Ecosystem in Penguin Country

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Figure 1: The marine foodweb of the west Antarctic Peninsula is characterized by large predators such as penguins, seals and whales sustained by upwelling that supports high productivity and large krill populations. Credit I. Heifetz, Rutgers University.

The PAL study region along the western Antarctic Peninsula is one of the most rapidly warming places on the planet (see below), and the ecosystem is responding to the rapid climate warming. Observations of the Antarctic marine food web since the 1970s indicate the development of a more complicated food web with new types of grazers and increased microbial activity (Figure 1). Krill populations - small shrimp-like animals eaten by penguins, seals and whales - are in decline.

Recently, gelatinous salps have been found in nearly every net tow and if krill are replaced by salps it would have important repercussions for the diet of larger predators.

A technique called inverse modeling has helped scientists incorporate their observations into food web models that yield estimates of key ecosystem process like photosynthesis, feeding, respirations and growth rates of krill, salps, penguins and bacteria. Changes they are seeing in the Antarctic presage equally larger changes closer to home.



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