The 279-foot research vessel Knorr from Woods Hole Oceanographic Institution of Woods Hole, Mass., returned to port on Mauritius after a monthlong expedition to the bottom of the Indian Ocean, laden with new insights into the ecosystems that form around hydrothermal vents. Funded by the National Science Foundation, the 34-member team on the Knorr, representing 12 institutions, mapped an area where three tectonic plates converge, collected biological and geological samples, and imaged black smokers and thermophilic marine life 2.5 miles below the surface. A Japanese research team had reported deep-sea vents in the area last fall, and the Knorr's crew confirmed the discovery. The chimneylike structures, which belch superheated water saturated with toxic metals, are surrounded by colonies of shrimp, anemones and crabs that are dependent on the chemosynthetic microbes that thrive in the sulfurous plumes.