(Mapleridgenews) Warm waters and infectious disease have been determined as the causes of a die-off of sunflower starfish along the Pacific Coast, says a new released study.
Sunflower sea stars are among the biggest starfish in the world and come in a variety of bright colors, including purple and orange. some of them grow to more than a metre long and are so fast they “literally run across the seascape,” said Joseph Gaydos, the senior author of the study.
“But when this disease happens, it’s like a zombie apocalypse,” said Gaydos, who’s with the SeaDoc Society out of the University of California, Davis.
“It can have twenty four arms and all of a sudden it’s walking around and its arms are just falling off. and then all of a sudden the whole body just looks to melt.”
So, what used to be a “big, lovely sea star,” and weighed about 5 kilograms resembles a pile of calcified parts within days, he said.
“It’s just a very ugly and quick disease for these sunflower sea stars.”
In 2013, scientists began noticing populations of the species declining between eighty and one hundred per cent in deep and shallow waters from Alaska and B.C. right down to California. The population information was collected by scuba divers and deep trawls.
Sunflower sea stars are found in waters from hundreds of metres to just 3 metres.
Diego Montecino-Latorre, a study co-author, and also from the University of California, Davis, said scientists found an association between increased water temperature and seeing fewer sea stars.
Gaydos said the temperature increases of the water weren’t the same in all areas.
Oceans are “not like a bathtub” with consistent temperatures throughout, he said, adding that some places in California saw an increase of about 4 Celsius while places in Washington noted an increase of 2.5 Celsius.
One of the theories put forward by scientists is that a rise in temperature makes the sea stars more susceptible to the disease that was already present, especially since sea stars don not have complex immune systems, he said.
Gaydos said the die-off is a warning call.
“It is hard to keep an eye on what is happening within the ocean but we need to pay attention because this happened over a very short period of time,” he said. “To have an entire species almost disappear, that is not good.”