Starfish disappearing

Photo: The Canadian Press

A newly released study says a combination of warm waters and infectious diseases has been determined as the cause of a die-off of populations of sunflower starfish along the Pacific coast.

Study co-author Drew Harvell, a Cornell University professor of ecology and evolutionary biology, says the heat wave in the oceans caused by global warming is making the sea star wasting disease worse and killing the starfish faster.

Scientists noticed that in the three years starting in 2013 the populations of this species declined between 80 and 100 per cent in deep and shallow waters from Alaska and British Columbia right down to California.

The study says the sunflower sea star is about the size of a manhole cover with an enormous appetite that crawls over the sea floor like a robotic vacuum cleaner, eating everything in its path.

Joseph Gaydos, with the SeaDoc Society out of the University of California, Davis, says sunflower sea stars are important because they keep sea urchins under control.

Gaydos, who's the senior author on the study, says without the sunflower stars, urchin populations expand and threaten kelp forests and biodiversity.