Scientists have returned from an unprecedented expedition to catalogue the tiny drifters of the deep – miniature flying snails, swimming worms and shrimp-like creatures that paddle themselves with oar-like feet.
These little life forms – known as zooplankton – are essential to life as we know it on Earth. Marine biologists usually study these creatures in relatively shallow water. But they wanted to know more about the populations in deeper water, between one and five kilometers down.
Scientists on research cruise in the Bermuda Triangle used specially designed nets to capture fragile sea creatures in deep water. It is part of an effort to produce a global inventory of zooplankton by 2010.
The 28 experts from 14 countries who were on board identified an incredible variety of zooplankton – at least 500 species -- but relatively few in number compared to the uppermost ocean layer. While still at sea, they sequenced the DNA of 220 of them. Some were less than a millimeter long. Others, including some of the jellyfish, were three to four centimeters in length.
Zooplankton feed bigger fish and marine mammals, including whales. They also help moderate the climate by transporting carbon to the bottom of the sea. Scientists fear global warming and other environmental changes may be having an effect of zooplankton – and the fish that depend upon them.
"We are charting the plankton in the sea like astronomers chart the stars in the sky," says Peter Wiebe, the cruise's scientific leader, and senior scientist at the Woods Hole Oceanographic Institution, USA.
"Without the zooplankton chart, we can assess what changes — man-made and natural —are taking place in the largest habitat on Earth. Without it, no assessment is really possible."
