On the horizon

Fresh water melt diluting the ocean

A rising amount of fresh water flowing into the Arctic Ocean from rivers, ice melt, and precipitation may account for the decreasing saltiness of the North Atlantic over the past 50 years, according to research published Friday in the journal Science.

Normally, oceanographers would assume that such changes were attributable to changes in ocean circulation and mixing patterns. But by comparing 50 years of data from the Arctic and North Atlantic, scientists from the Woods Hole (Mass.) Oceanographic Institution, the University of Texas at Austin, and other research centers established that "rivers, ice melt, and precipitation have a large influence," according to James McClelland, a marine scientist at the University of Texas.

The findings are significant because researchers have been looking at whether the increased flow of fresh water, connected to warming air temperatures, could – paradoxically – cool Northern Europe.

"The high-latitude freshwater cycle is one of the most sensitive barometers of the impact of changes in climate," says Bruce Peterson of the Marine Biological Laboratory in Woods Hole. He notes that Earth's polar regions have been warming faster than other areas of the world.

The trap-jaw ant can snap its mandibles closed in less than a millisecond – moving 2,300 times faster than the blink of an eye. The ant has the fastest bite ever recorded, reaching speeds of 145 m.p.h., according to new research.

High-speed-video studies of trap-jaw ants collected in Costa Rica show the insects' jaws generate forces exceeding 300 times the creatures' body weight. "The mandibles are operating in the outer known limits in biology in terms of speed and acceleration," says Sheila Patek of the University of California at Berkeley, whose team published findings in the Aug. 21 issue of Proceedings of the National Academy of Sciences.

The ants use their jaws not only to catch prey, but also to launch themselves in the air to escape predators.

Brazilian paleontologists have discovered a new giant dinosaur species based on fossilized fragments of the herbivorous reptile that lived 80 million years ago. The Maxakalisaurus topai, of the Titanosauria group, was 13 meters (43 feet) long and weighed an estimated nine tons. It had a long tail and neck with a relatively small head. The fossils were found between 1998 and 2002 in Brazil's central-southern Minas Gerais state.

Maxakalisaurus topai is closely related to a highly evolved group of dinosaurs, the Saltasaurinae, whose fossils have been found only in Argentina.