Genome experts who took on a patch of ocean for a mass gene-sequencing project said they had discovered at least 1,800 new species of microbes and changed some of their fundamental ideas about ocean biology. Genome pioneer Craig Venter and other scientists analyzed the tiny organisms in a sample of water from the Sargasso Sea off Bermuda and then sequenced the genetic code. They used the technique that Venter, now at his own nonprofit institute, used to accelerate the sequencing of the human gene map.