When '80s pop star Thomas Dolby sang "She blinded me with science," little did he know that his bouncy lyric prophesied the fate of shrimp deep in the Atlantic. Researchers now claim that the bright lights of research submarines may destroy the delicate eyes of shrimp that live near hot vents on the sea floor, according to a report in tomorrow's issue of Nature.
Mineral-rich fluids gush into the sea at many spots along the Mid-Atlantic Ridge, an oozing suture in the planet's crust more than 2 kilometers below sea level. These hydrothermal vents support a bizarre menagerie, from giant tubeworms to writhing swarms of shrimp. In 1989, scientists found patches of pink pigmented cells on the backs of the shrimp that detect light without creating an image. Such dark-adapted "eyes" may sense the glow from superheated water or bioluminescent organisms.
Now, it appears that the mere act of observing the shrimp can darken their world for good. Oceanographer Peter Herring of the Southampton Oceanography Centre in England and his co-workers captured shrimp from two vents southwest of the Azores in August 1997. At one vent, visited for the first time a month earlier, many shrimp eyes were a healthy pink. However, the eyes of most shrimp from the other site--heavily visited over the years--were a chalky white. Their pigmented light-sensing layers were completely destroyed.
Herring suspects that a research sub's brilliant lights triggered an irreversible breakdown of the eye photoreceptors, as surely as staring at the sun would blind a person. "Bright lights are pollutants in the deep sea that can cause damage not immediately obvious to the casual observer," Herring says. However, studies of shrimp near the surface show that blinded shrimp have the same growth and survival rates as their sighted kin. "Vision may be a bonus but not an essential aspect of life for them," he observes.
Some scientists already worry that submersible vessels harm hydrothermal ecosystems by bumping into vent chimneys or touching organisms, says marine ecologist Lauren Mullineaux of the Woods Hole Oceanographic Institution in Massachusetts. "It was an eye-opener that we need to pay attention to more than just physical disruption," she says. Any proposal to protect some vent systems from exploration may need to make them off limits to observers as well, Mullineaux says.