The scientists said their discovery might explain why the surface waters of the southeast Pacific Ocean are so poor in nutrients, making the environment inhospitable to life.

To determine how solar ultraviolet radiation affects those waters, a team led by researchers from the Laboratory of Marine Microbiology Geochemistry and Ecology at the University of the Mediterranean in Marseilles, France, sampled the southeast Pacific. They found that in the extremely nutrient-poor waters of the South Pacific near Easter Island, ultraviolet radiation penetrates up to 328 feet into the ocean. Those measurements are the highest ever reported for oceanic waters and are equal to those measured in the clearest freshwaters.

Because ultraviolet radiation can degrade organic matter and damage DNA, the investigators expect their findings will lend insight into marine ecosystem health and the marine carbon cycle.

The study -- which involved researchers from Science Systems and Applications Inc. of Lanham, Md.; Hokkaido University in Sapporo, Japan; and the University of Georgia in Athens, Ga. -- appears in the journal Geophysical Research Letters.