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Isabella O’Malley
Digital Writer/Climate Change Reporter
Sunday, February 3, 2019, 1:41 PM – Since 2013 marine scientists have observed the spread of ‘zombie disease’ among different types of star fish, and a new study indicates that the warming ocean temperatures are playing a role in the mass die-offs.
The study, published in Science Advances, analyzes various star fish species in the Pacific Ocean and their susceptibility to sea star wasting disease (SSWD), which causes the formation of small, white lesions and then leads to the loss of limbs.
Along the Pacific coasts, from Mexico to Alaska, more than 20 different star fish species have been impacted by the disease. As the disease progressively worsens the dermal lesions, the limbs become detached from the center of the star fish and hinders their ability to reproduce, which contributes to population decline.
The study finds that peak declines in star fish populations coincides with anomalously warm sea surface temperatures, particularly when there are ‘ocean heat waves.’
The researchers explain that the increasingly abnormal temperatures have been shown to influence the prevalence and severity of marine infectious diseases, which has been confirmed in a number of experimental and field studies.
The leg of this purple ochre sea star in Oregon is disintegrating, as it dies from sea star wasting syndrome. Credit: Wikimedia Commons
Similar to the human body, sea stars reach optimal health at specific temperatures. When these temperatures are higher than normal for long periods of time their bodies undergo stress, which puts them at a higher risk of suffering from infections that can progress to mortality.
Previous research has suggests that the disease could be associated with a virus (sea star-associated densovirus or SSaDV) that is able to initiate wasting is sea stars, but it has not been confirmed that it played a role in many of the largest sea star die-offs.
While determining the exact cause of the disease will require more research, the study’s results indicate a grim reality for many Pacific sea stars. Since 2013 over 20 species of sea stars have seen population declines between 80 and 100 per cent from Alaska to British Columbia.
Areas that were once dense with brightly coloured sea stars are now bare with the exception of small populations where the disease is widespread, and sea stars can be seen walking around with their limbs falling off, as shown in the video above.
The researchers emphasize that these findings are not an isolated observance, but a widespread, multi-national environment emergency that confirm that dire conditions marine ecosystems are facing.
Science director of the SeaDoc Society at the University of California, Joseph Gaydos, explained that conservationists are looking at ways to preserve the species, in an interview with CBC.
“If we all start doing things, we’re going to have some impact. We can’t just throw our hands up,” stated Gaydos.
With files from CBC Radio.
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