The Mysterious Movements of Deep-Sea Larvae

About Deep Sea Life

The article below from WHOI has been sent to you by trajano@sosoceanos.org

http://www.whoi.edu/oceanus/viewArticle.do?id=65406

The Mysterious Movements of Deep-Sea Larvae

The marvelous migrations of fish and whales through the deep sea have been hard enough for us humans to follow. But what about tiny organisms—many smaller than the dot beneath this question mark? How they move from one spot to another in the depths has long remained beyond our grasp.

The enigma deepened in 1977, when scientists discovered spectacular and strange communities of animals clustered near vents on the seafloor. These so-called hydrothermal vents spew chemical-rich fluids that sustain clams, mussels, tubeworms, snails, and other species. Like shellfish in shallow waters, most of these relatively sedentary deep-sea animals reproduce by releasing eggs and sperm into the water. These develop into tiny floating larvae—the aquatic animal equivalent of seeds—that disperse, settle at vent sites, and grow.

Here’s the catch: The vents are distributed intermittently along mid-ocean ridges—the long volcanic mountain chains that bisect the seafloor throughout the globe. These vents “turn on” and “turn off,” fueled by the ebbs and flows of hot magma beneath the seafloor.

So how do the larvae, tinier than specks of dust, maintain their populations in such a patchy, transient environment? How do they get transported from one active vent site to another that might be tens of miles or more away?

These questions are keys to understanding how life has evolved on the seafloor and how it survives. Answering them requires a blend of biology, oceanographic physics, geology, and chemistry.