Dozens of dolphins swam out of the polluted waters of Haifa Harbor on Tuesday.This was the first time that dolphins had visited this crowded Mediterranean port,and researchers were surprised and delighted by the unexpected event. Between 40 and 50 of the dolphins appeared in the busy port on Tuesday morning,obviously drawn by the fishrich waters of Haifa Harbor. However,the bay is also full of harmful chemicals. Aviad Sheinin,professor of Haifa University's Maritime Studies Department,said he didn't think the dolphins were harmed by the pollution,but he hoped that they would swim back to the sea soon. "It seems that they are quite relaxed. They don't seem to be stressed," he said. Haifa Harbor is lined by chemical companies that have been pouring poisonous waste into the water for decades. While pollution levels have dropped in recent years,the water is still considered a health hazard. "There are lots of fish in Haifa Harbor. Unfortunately we couldn't tell the dolphins that the fish are not healthy;and I don't know what the result will be," he told Israel Army Radio.Hundreds of Haifa residents gathered around Haifa Harbor to see the interesting sight,and researchers said this provided a rare chance to film and study the roughtoothed dolphins. In addition to the dozens of dolphins which swam into the port on Tuesday,a similar number stayed outside the breakwater .Later Tuesday the dolphins left the port but remained near the entrance and Israel's coast guard was patrolling  the area to try to make sure the dolphins didn't reenter the poisonous waters. Relatively little is known about roughtoothed dolphins,which are usually found in deep and warm tropical waters. This passage mainly tells us that   _  .
dolphins are well protected in Israel people love dolphins dolphins made a surprise visit to the polluted harbor Haifa Harbor is full of harmful chemicals