Mass starfish death is biggest disease epidemic ever seen in marine animals, scientists say

Sunflower sea star hit by 'devastating' population decline which threatens biodiversity

Jon Sharman
Thursday 31 January 2019 17:51 GMT
A sunflower sea star, one of the species that has been hit hard by a wasting disease
A sunflower sea star, one of the species that has been hit hard by a wasting disease (Brocken Inaglory/Wikimedia)

Starfish along the US Pacific coast have been hit by the worst-ever disease outbreak seen in wild marine animals with one key species almost entirely wiped out, scientists say.

Sea star wasting disease has caused a “devastating” decline in the once-common sunflower sea star - Pycnopodia helianthoides - that is deemed important because it eats sea urchins which, left unchecked, can chew through swathes of kelp forests relied on by a host of other creatures.

Researchers identified warming temperatures and increased deaths during their survey of P helianthoides in a 3,000km stretch of coast from California to British Columbia.

Using data from divers and seabed trawls they found declines of up to 100 per cent in some areas, and said they feared the species may not recover.

Its near-total disappearance between 2013 and 2017 has already been linked with an increase in urchin population and reduction in kelp, threatening biodiversity, according to the study published in Science Advances.

In the paper, the scientists add: “Timing of peak declines in near-shore waters coincided with anomalously warm sea surface temperatures.

“Increasingly warm or anomalous temperatures are being shown to influence the prevalence and severity of marine infectious diseases ... [while] experimental and field studies support a role for temperature in sea star wasting disease morbidity.”

Animals affected by the disease, thought to be caused by a densovirus, develop white skin lesions before their arms fall off and they die.

Researchers quantified the collapse of P helianthoides by using data spanning 2004 to 2017.

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