Marine biologists say they are baffled by the mysterious deaths of hundreds of dolphins near east Africa's Zanzibar islands.
Scientists Tuesday are studying samples from at The dolphins showed no visible signs of trauma. Some scientists have speculated that oil pollution, poisonous seaweed, toxic algae or even the powerful sonar from submarines could have caused their deaths.
Results from tests on tissue samples are expected in two weeks.
Watching and swimming with herds of dolphins are popular tourist attractions on the Zanzibar islands, which lie just off mainland Tanzania in east Africa.
Some information for this report was provided by AP and Reuters.