Two researchers say they have found a mysterious "dead zone" in Louisiana's largest lake -- a black area on the bottom of Lake Pontchartrain that is virtually devoid of life. And the husband and wife team say they can't interest the federal or state government in funding exploration to determine the cause or size of the area, which lacks the tiny creatures that provide food for most fish and shellfish. Dr. Walter Sikora and Dr. Jean Sikora of Louisiana State University's coast studies team said they discovered the "dead zone" during a three-year study of the lake bottom. In the study, they took samples of bottom sediment from the lake, which has a low salt content, and kept track of the number of different bottom creatures. As they were completing the study in September, they found an unusual bottom sample a mile off Pontchartrain Beach. "The sediment was black as tar," Sikora said. There was practically nothing alive in it. "We dumped it overboard. We backed the boat up about 15 feet and tried again," he said. Again, the sample was black, lifeless and smelled of decay. They took three samples -- all with the same result -- and moved to another site six miles away. Again, they found black sediment devoid of life except for a few microscopic species they said could have been swept in by currents. Of the tiny current-carried species, 12 kinds died in the "dead zone" and three others were drastically reduced in number, they said. Initial tests on the samples turned up three "halogenated" organic compounds -- compounds containing any of the five nonmetallic chemical elements fluorine, chlorine, bromine, astatine and iodine.