On the horizon: news from the frontiers of science

New insights into Saturn's icy moon, how fish help coral reefs, and what is a Gorgeted Puffleg anyway?

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A newly discovered Hummingbird

Two scientists in Colombia have announced the discovery of a new species of hummingbird in a mountain ecosystem threatened by slash-and-burn farming. The duo initially saw the bird – the Gorgeted Puffleg or Eriocnemis isabellaein 2005 in the cloud forests of the Serrania del Pinche mountains in southwestern Colombia. Last year, they returned for additional sightings.

The two began their search after hearing that a new plant species has been discovered in the region in 1994. They suspected that they might find new vertebrate species in the region as well – perhaps new amphibians or added range for previously known birds. "The discovery of a new hummingbird was completely unexpected," says Alexander Cortes-Diago, one of the two researchers.

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The discovery is prompting environmental groups to ask that the area be set aside as a reserve. They note that because the bird has remained hidden for so long, its range is likely to be very limited and thus very vulnerable to human encroachment.

So that's how Enceladus does it!

Astronomers studying Saturn's moon Enceladus were stunned two years ago to find ice and water erupting into space from its surface. The eruptions, spotted by the Cassini spacecraft, occurred in a relatively warm region on the moon, where the icy surface is laced with faults dubbed "tiger stripes."

Some speculated that the water came from an ocean close to the surface. Now, a team led by Francis Nimmo at the University of California at Santa Cruz suggests that the water and ice crystals originate at the surface. The tug of Saturn's gravity on the moon as it orbits around the planet causes faults in the surface ice to shift up to 20 inches with each orbit. The friction causes heat, which produces the water and ice shards. The team outlines its ideas in Thursday's issue of the journal Nature.

The group still buys the idea of an ocean beneath the ice. If the icy layer is anchored to solid rock, it would lack the flexibility to shift the way it does. But the ocean may be at least three miles under the surface.

Protecting fish helps coral reefs

Marine reserves, where fishing and many other activities are prohibited or tightly regulated, may hold a key to preserving coral reefs, British researchers say.

The scientists, from the University of Exeter, used the Exuma Cays Land and Sea Park in the Bahamas as their laboratory. They found that young coral colonies flourish in sections of the reef where native fish such as parrotfish are protected. These young colonies become the basis for rebuilding the reef when older corals die because of bleaching or storms. The native fish graze on seaweed, which otherwise would overrun damaged portions of the reef.

The park, which covers 442 square miles, is deemed the largest and most successful marine park in the Caribbean. The researchers say that while the value of marine reserves in protecting fish is well documented, this is the first study to show how that protection trickles down to protect coral reefs. The work appears in this week's issue of The Proceedings of the National Academies of Science.

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