A sea star of the species Pycnopodia helianthoides
The head of mass death was finally identified, more than a decade after the beginning of the massacre that left terror scenarios through the oceans.
More than a decade after the start of a round of sea stars, along the Pacific North America coast, scientists identified the responsible agent: a genus of the genre Vibriorelated far from cholera.
A Sunflower starfish (Pycnopodia helianthoides) It was the most affected by this “serial killer.” The outbreak began in 2013 when marine divers and researchers detected the abrupt disappearance of millions of sea stars, especially off the state of Washington.
The team found a terror scenarioRemember: twisted arms that loosened from the body and rapid disintegration. The phenomenon, designated by “Star-of-sea wear syndrome”It affected more than 20 species and caused the death of thousands of millions of individuals.
Although similar outbreaks were recorded in California and Mexico in the 1980s and 1990s, the scale and extension of the outbreak started in 2013-which extended to Alaska-was unprecedented, and it is believed that the warming of the oceans caused by climate change may have played a relevant role.
In early 2021, a study concluded that the culprit was not a bacteria, but the: the stars of the sea died suffocated, the authors said. But a study this Monday at Nature Ecology & Evolution reveals that the bacteria Vibrio pectenicidastrain Fhcf-3is responsible. It is a microorganism already known for infecting other marine invertebrates, such as scallops in France and bivalve mollusks in the state of Washington.
The investigation, led by Alyssa-Lois Gehman and Melanie Prentice of the Hakai Institute in Canada, initially pointed out that the pathogen agent would be viral, but experiments with filtered tissues-with bacteria removal-did not cause healthy stars disease. When sick starfish non-filtered body fluid was used, animals fell ill quickly, as it was observed in nature.
Genetic analysis of body fluid revealed a dominant presence of Bacteria DNA Vibrio pectenicida in sick animals. The investigators were able to isolate the FHCF-3 strain and, in controlled tests, showed that their healthy starfish introduction caused the same lethal symptoms. Higher doses accelerated the onset of the disease: Symptoms appeared after 5 days and death occurred shortly after.
The disease had serious ecological consequences: with the fall of the star populations, the sea urchin – of which these are natural predators – proliferatedleading to the devastation of algae forests, crucial sea habitats for numerous species.
The team now intends to understand if the same strain affects other species of starfish. Body fluid samples of 12 other species were collected in areas affected by the disease.
Also conservation efforts are also taking place. Several groups are creating sunflower starfish in captivity to repopulate affected areas.
And just as the sunflower is the flower of positivity, the same seems to happen to the sunflower of the animal kingdom. This summer were sighted in the Youth Sunflower Stars in Northern California and Oregon-the first records since the early epidemic, which hopes that the species can recover, arm-to-arm.
Tomás Guimarães, Zap //
