A team led by researchers from British Columbia has resolved the mystery of a terrible disease that has decimated billions of starfish along the Pacific Coast of North America, more than ten years after their disappearance.
Melanie Prentice, the main author of a new study, recalls a moment when she did not really believe in it when the researchers discovered an abundant bacterial strain in sick starfish and absent in healthy starfish.
“My first reaction was to say to me:” OK, I made a mistake, “she said.
Melanie Prentice explained that the team had spent months attempting to refute their conclusions, finally confirming having deciphered the disease code.
They discovered that the Vibrio Pectenicida bacteria is an obvious cause of starfish disease.
“This is a question to which researchers have been trying to answer for about 12 years, so we are more than delighted,” said Ms. Prentice, associate researcher at the Hakai Institute and the Department of Earth Sciences, the Ocean and the atmosphere of the University of British Columbia (UBC).
The article detailing the four -year research project and its conclusions was published online on Monday in the journal Nature Ecology & Evolution.
Alyssa Gehman, who contributed to the launch of the project in 2021, described the disease as “appalling”, causing the appearance of lesions in the starfish, the loss of their arms and their “porridge disappearance” about a week or two after exposure to the pathogen.
It was particularly deadly for sunflower starfish, killing about six billion of these starfish that can develop 24 arms and reach a wingspan of one meter.
The giant seas of sea are now considered functionally extinct in a large part of their old distribution area off the continental coast of the United States, with losses exceeding 87 % in the “North refuges” where they persist, according to the study.
A pillar of the ecosystem
This collapse has had cascading consequences, including the massive disappearance of important varech forests on the ecological, cultural and economic levels.
“I think we didn’t really realize their importance before losing them,” said Mr.me Prentice, describing the oranges, purple or brown sunny starfish as a “keystone” species having a considerable impact on their ecosystem.
Giant starfish are leading predators, inspiring fear for other invertebrates.
“Almost everything that lives on the ground underwater flee when they arrive,” said Mr.me Gehman, an environmentalist specializing in marine diseases at the Hakai Institute and assistant professor at the Institute of Oceans and Fisheries of the UBC.
They control the sea urchins, thus ensuring the health of the Varech forests which provide habitat and food to many other species.
The devastation of the starfish starfish caused a “total change in the ecosystem”, described Melanie Prentice, transforming Varech forests rich into “terrible deserts of sea urchins”.
The bacteria responsible for the decline in the starfish had remained elusive for more than ten years, since starfish was observed for the first time in 2013, dying in large numbers. This same bacteria is known to attack scallops.
It sometimes looks like science fiction.
This discovery allows researchers to focus on deeper questions, in particular the possible role of warming ocean and the possibility of raising seas of seas of captivity to promote resistance to diseases and accelerate restoration, argued Alyssa Gehman.
The disease now seems seasonal, with epidemics occurring during the hottest months, which suggests that temperature could be a factor, she added. She will soon carry out temperature experiences to deepen her research.
These results could help researchers understand where starfish could be faced with climate change in the future.
Melanie Prentice indicated that there are “remaining” populations of sunflower starfish along the coast of British Columbia, and that some of them are more resistant to debilitating disease.
She added that the discovery and selective breeding of seas of sea more resistant to the disease could produce “super” starfish intended to be reintroduced into the wild.
“It sometimes looks like science fiction, but work is underway,” she concluded.
