Wednesday, November 29, 2006
Flushing Submarine Canyons
Barcelona (Spain), 28 November: Large amounts of sediment can be transported from shallow waters to the deep ocean by the cascading of cold, dense waters, a study in this week's Nature suggests. As climate changes, this could have repercussions for the environment.
Water and sediment are transferred to the bottom of the ocean via steep-sided valleys called submarine canyons. It's currently thought that most of these flows are initiated by river floods or sediment collapse. But now Miquel Canals and colleagues show that the process can also be triggered by changes in seawater density.
Future changes in climate could alter the frequency and intensity of these dense shelf water cascading events, which also reshape the canyon floors. So there may be knock-on effects for deep-sea ecosystems and carbon storage.
(ResearchSEA)
Water and sediment are transferred to the bottom of the ocean via steep-sided valleys called submarine canyons. It's currently thought that most of these flows are initiated by river floods or sediment collapse. But now Miquel Canals and colleagues show that the process can also be triggered by changes in seawater density.
Future changes in climate could alter the frequency and intensity of these dense shelf water cascading events, which also reshape the canyon floors. So there may be knock-on effects for deep-sea ecosystems and carbon storage.
(ResearchSEA)
Discovery May Help Defeat Gypsy Moth
LA (USA), 28 November: Ecologists have spotted a never-before-seen pattern in encroachment of gypsy moth (Lymantria dispar) in northeastern United States. The moths' invasion occurs in periodic pulses rather than as a smooth wave- controlling population peaks at frontiers may therefore help to fight their spread.
Gypsy moth invasion is arguably the most intensively studied species invasion in history. Since its accidental release near Boston in 1869, the species has swarmed across more than a million square kilometers of United States, defoliating up to 50,000 square kilometers of forest each year.
By analyzing more than four decades' worth of data stretching back to 1960, researchers led by Derek Johnson have spotted that the moths' spread happens in pulses, which occur roughly every four years. As they explain in this week's Nature, this is probably because moths that spread far beyond the current frontier cannot establish breeding populations unless they colonize in sufficient numbers. Thus, moths can spread only at times when their populations are high and so targeting large groups of moths near the edges of the current distribution could help to slow their advance.
(ResearchSEA)
Gypsy moth invasion is arguably the most intensively studied species invasion in history. Since its accidental release near Boston in 1869, the species has swarmed across more than a million square kilometers of United States, defoliating up to 50,000 square kilometers of forest each year.
By analyzing more than four decades' worth of data stretching back to 1960, researchers led by Derek Johnson have spotted that the moths' spread happens in pulses, which occur roughly every four years. As they explain in this week's Nature, this is probably because moths that spread far beyond the current frontier cannot establish breeding populations unless they colonize in sufficient numbers. Thus, moths can spread only at times when their populations are high and so targeting large groups of moths near the edges of the current distribution could help to slow their advance.
(ResearchSEA)
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