A research team from British Columbia has made significant progress in understanding the sea star wasting disease, which has decimated billions of sea stars along the Pacific coast since its emergence over a decade ago. Led by Melanie Prentice, the team discovered that the bacterium Vibrio pectenicida is a major cause of this devastating disease. Initially unsure of their findings, Prentice and her colleagues dedicated months to disproving their results before confirming the bacterium’s role in the disease. Their study, published in Nature Ecology & Evolution, marks a pivotal moment in answering a question scientists have been grappling with for years, showcasing the importance of thorough scientific inquiry.
The disease is particularly lethal to sunflower sea stars, with an estimated six billion individuals lost. This species, known for its ability to sprout up to 24 arms, has been declared functionally extinct in many parts of its habitat. The decline of sunflower sea stars has led to significant ecological repercussions, including the degradation of kelp forests that play a vital role in marine ecosystems. Prentice highlights that the ecological importance of these sea stars was more fully appreciated only after their populations collapsed. Described as a keystone species, sunflower stars are crucial for maintaining balance within underwater ecosystems.
Sunflower sea stars serve as top predators within their environment, controlling populations of sea urchins, which, if unchecked, can devastate kelp forests. The loss of these sea stars has resulted in what Prentice calls a "total ecosystem shift," with vibrant kelp forests transforming into barren areas dominated by urchins. This shift underscores the significant interconnectedness within marine habitats and how the decline of a single species can lead to broader ecological ramifications. The research team’s long-standing pursuit of understanding this disease highlights the complexities of marine ecosystems and the delicate balance they maintain.
The breakthrough in identifying Vibrio pectenicida stemmed from a methodological shift in the research approach. Previous studies focused primarily on diseased tissues, overlooking the coelomic fluid, which acts as a blood-like substance in sea stars. By examining this fluid, the researchers were able to demonstrate the pathogenicity of the bacterium in healthy sea stars. Prentice’s innovative approach not only confirmed the presence of harmful bacterial species in diseased individuals but also elucidated their absence in healthy counterparts, providing a clear link between Vibrio pectenicida and the wasting disease.
Prentice’s systematic analysis of microbial species across both healthy and diseased sea stars culminated in the identification of Vibrio pectenicida as a consistent agent in the samples collected from dying sea stars. The discovery, hailed as a significant achievement by the research team, paves the way for future investigations into potential factors affecting the disease’s progression, including climate impacts and temperature fluctuations. Alyssa Gehman, who contributed to the study, expressed her relief at the simplicity of the findings, which contradicts earlier assumptions that the disease would prove multifaceted and complicated.
With this newfound understanding, the researchers aim to explore the relationship between ocean warming and bacterial growth rates to assess their impact on sea star populations. The potential for breeding sea stars with enhanced resistance to the disease could aid conservation efforts, offering a glimpse into the feasibility of reintroducing ‘superstar’ sea stars into the wild. Such initiatives could play a crucial role in the recovery of sunflower sea stars and their ecosystem services, as these remarkable creatures hold a critical place in maintaining marine biodiversity. The ongoing collaboration in marine research promises further insights into the resilience and future of these vital species amid changing ocean conditions.
