Sea star wasting disease (SSWD) or starfish wasting syndrome is a disease of starfish and several other echinoderms that appears sporadically, causing mass mortality of those affected. The disease has affected over 20 species of sea stars, many of which are found on the western coast of North America. The disease seems to be associated with increased water temperatures in some locales, but not others. It starts with the emergence of lesions, followed by body fragmentation and death. As of 2025, more than 5 billion sea stars have been lost from the 2013 plague, resulting in a population decline of over 90% in some species. The decimated numbers of sea stars on the Pacific Northwest coast has lead to major ecosystem imbalance, with rising sea urchin populations due to the lack of sea star predation, which uncontrollably feed on the local kelp forests. In 2014, it was suggested that the disease is associated with a single-stranded DNA virus now known as the sea star-associated densovirus (SSaDV), but this hypothesis was refuted by research in 2018 and 2020. In 2025, a study published in the journal Nature Ecology and Evolution showed that the bacterium Vibrio pectenicida strain FHCF-3 caused a SSWD-like condition in Pynopodia helianthoides.
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👉 Sea star wasting disease in the context of Seaweed
Seaweed, or macroalgae, refers to thousands of species of macroscopic, multicellular, marine algae. The term includes some types of Rhodophyta (red), Phaeophyta (brown) and Chlorophyta (green) macroalgae. Seaweed species such as kelps provide essential nursery habitat for fisheries and other marine species and thus protect food sources; other species, such as planktonic algae, play a vital role in capturing carbon and producing at least 50% of Earth's oxygen.
Natural seaweed ecosystems are sometimes under threat from human activity. For example, mechanical dredging of kelp destroys the resource and dependent fisheries. Other forces also threaten some seaweed ecosystems; for example, a wasting disease in predators of purple urchins has led to an urchin population surge which has destroyed large kelp forest regions off the coast of California.
Sea star wasting disease in the context of Marine heatwave
A marine heatwave is a period of abnormally high sea surface temperatures (SST) compared to typical temperatures for a particular season and locale. Marine heatwaves are caused by a variety of drivers. These include short term weather events such as fronts, intraseasonal events (30 to 90 days), annual, and decadal (10-year) modes like El Niño events, and human-caused climate change. Such heatwaves affect marine ecosystems. For example, heatwaves can lead to events such as coral bleaching, sea star wasting disease, harmful algal blooms, and mass mortality of benthic communities. Unlike heatwaves on land, marine heatwaves can extend over vast areas, persist for weeks to months to years, and extend to subsurface levels.
Major marine heatwaves affected the Great Barrier Reef in 2002, the Mediterranean Sea in 2003, the Northwest Atlantic in 2012, and the Northeast Pacific during 2013–2016. These events had drastic, long-term impacts.
Sea star wasting disease in the context of Sea star-associated densovirus
Sea star-associated densovirus (SSaDV) belongs to the Parvoviridae family. Like the other members of its family, it is a single-stranded DNA virus. SSaDV has been suggested to be an etiological agent of sea star wasting disease, but conclusive evidence has not yet been obtained. Further work in 2018 and 2020 re-examined the association between SSaDV and sea star wasting and found no evidence in both the original work and subsequent surveys of sea stars. More recently, densoviruses associated with echinoderms were recognized as forming persistent infections in their hosts and become endogenized within sea star genomic DNA. Densoviruses including SSaDV become more pronounced during sea star wasting progression, but no single strain is associated with sea star wasting disease.
Sea star wasting disease in the context of Vibrio pectenicida
Vibrio pectenicida, sometimes abbreviated V. pec, is a species of bacterium, of which strain A365 is associated with disease in scallop (Pecten maximus) larvae. Strain A365 is the type strain (= CIP 105190) and does not use glucose or fructose as carbon sources, but uses rhamnose and betaine.
Vibrio pectenicida strain FHCF-3 has been identified as a causative agent of a sea star wasting disease in Pycnopodia helianthoides. The draft genome is 4,368,354 bp and has 3,903 coding sequences, three of which encode putative aerolysin-like toxins that can disrupt cellular membranes and are associated with virulence. The bacterium responds to enrichment with a variety of organic matter sources on asteroid surfaces, and was found in healthy sea cucumbers and sea stars, along with plankton in Australia, Hong Kong, and Okinawa.