On the horizon

News from the frontiers of science.

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Drought and snails fell marsh grass

Over the past six years, the US East and Gulf Coasts have lost salt marshes at an unprecedented rate. Scientists blame drought and increasing soil salinity as the main culprits. Now an international team of researchers adds another villain: periwinkle snails.

Drought and snails combine in a potent one-two punch when a drought is under way. But even after the drought eases, snails can continue devastating a marsh.

Besides eating the grass, snails introduce a fungus that drought-weakened grasses can't endure. Where the grass was stressed by drought alone, growth fell 45 percent. When snails were added, the biomass tied up in grasses fell by 84 percent.

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One reason for the growth in snails: increased fishing for delectable blue crabs, which feed on snails.

The team, led by University of Florida zoologist Brian Sillman, says its results show the strong interaction between climate and grazers and the potential they hold for a coastal marsh's collapse.

The results appear in the current issue of the journal Science.

How to grow salt-tolerant crops

Researchers at the University of Haifa in Israel have identified a salt-tolerant gene that they say could help crops grow in increasingly marginal land.

The team was looking at the genetic makeup of a fungus that lives in the Dead Sea, in part to study how organisms evolve to survive the sea's rapidly rising salinity. The Dead Sea is 10 times saltier than the ocean.

The scientists isolated a gene that they say is responsible for conferring salt and freeze-thaw tolerance to the fungus.

They then introduced it into a wild variant of baker's yeast. Yeast with the new gene was far more tolerant of temperature changes, salinity, and lithium concentrations than yeast without the gene.

Genes in the Dead Sea fungi may be "a potentially promising resource to improve salt tolerance" in other organisms and in crops, researchers say.

NASA sets its sights on Pluto

NASA is preparing to launch the first spacecraft to Pluto and its moon Charon. Next month's launch of New Horizons will complete the initial reconnaissance of the planets in the solar system.

"New Horizons will study a unique world, and we can only imagine what we may learn," says Mary Cleave, associate administrator for NASA's Science Mission Directorate.

The National Academy of Sciences ranks the exploration of Pluto-Charon and the Kuiper Belt among the highest priorities for exploration, citing the importance of exploring these bodies to understanding our solar system.

Unlike the inner, rocky planets (like Earth) or the outer gas giants, Pluto is an "ice dwarf," common to the Kuiper Belt, which is billions of miles from the sun.

"Exploring Pluto and the Kuiper Belt is like conducting an archaeological dig into the history of the outer solar system, a place where we can peek into the ancient era of planetary formation," says Alan Stern, New Horizons's principal investigator at the Southwest Research Institute Department of Space Studies in Boulder, Colo.

Designed and built at the Johns Hopkins University Applied Physics Laboratory in Laurel, Md., New Horizons is set to launch from Cape Canaveral, Fla., no earlier than Jan. 17, 2006. The compact, 1,050-pound, piano-sized probe will launch aboard an Atlas V rocket.

Material from the Associated Press was used in this report

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