June 2011

A joint research effort between the University of Hawaii at Mānoa's Hawai'i Institute of Marine Biology(HIMB), University of Tokyo, the Japanese National Institute of Polar Research and the University of Florida has shed new light on the hunting behavior of tiger sharks.

Cosmopolitan predators with large home ranges, tiger sharks consume a wide variety of prey, often moving hundreds of kilometers between oceanic islands and far out into open ocean to fill their resource needs.

Australian Institute of Marine Science (AIMS) scientist Dr Katharina Fabricius has led two research expeditions, with researchers from six countries including Papua New Guinea (PNG), to study three natural CO2 seeps in Milne Bay Province, PNG. This unique location is the only presently known cool, CO2 seep site in tropical waters containing coral reef ecosystems. The study has given scientists unprecedented insights into what coral reefs would look like if greenhouse gas emissions and resulting ocean acidification continues to increase at present rates.

“The findings add fuel to an already fierce debate in the research community on how the echolocation sound is produced”, says Josefin Starkhammar.

Dr Starkhammar’s own guess is that the two sound projections come from the two different sound-producing organs, the existence of which is well known, but it was believed that only one was active during echolocation. She stresses that more research is needed. For example, the two projections could also be explained by complicated reflections in the head of the dolphin, where the sound is formed.