Researchers have found no evidence of poisoned sea plants or fish as a result of toxic copper ore that has leaked from a sunken freighter but they continued to express concern about the long-term effects of the spill. The research team from the Marine Science Institute of the University of California, Santa Barbara, has been taking water and fish samples and will release a preliminary report in about three weeks, visiting researcher Stanley Margolis said. Analysis of the water samples will indicate how fast the ore is dissolving, and the fish samples will enable researchers to determine whether the copper has entered the food chain, authorities said. The research team has been taking sonar images of the 550-foot Pac Baroness, which collided with another ship Sept. 21 and sank in 1,500 feet of water about 15 miles off Point Conception. The high-resolution sonar, similar to that used in the Atlantic to locate the wreck of the Titanic, found that the freighter is on its side and has broken into three pieces.