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The Great Starfish Die-Off

Between the years of 2013-2014 one of the most prolific and devastating die-offs of a single species occurred down the western coast of North America. This loss of life in such an extreme magnitude went widely unnoticed due to the nature of the situation. We humans for once had no clue what was happening. Over 25 different species of sea star contracted and spread what is known today as SSWS or Sea Star Wasting Disease. These events have occurred and have been documented from the 1970’s to the early 2000’s though the damage was very minor, so minor in fact that most scientists simply shrugged the event off as a coincidence of the technological revolution. However the event was real and was extremely deadly. Sea star wasting syndrome is a general description of a set of symptoms that are found in sea stars. Typically, lesions (sores/stress marks similar to coral bleaching) appear in the ectoderm followed by decay of tissue surrounding the lesions, which can lead to eventual fragmentation of the body and death. A deflated appearance can precede other physical signs of the disease. All of these symptoms are also associated with ordinary attributes of unhealthy stars and can arise when an individual is stranded too high in the intertidal zone (for example) and simply desiccates. True wasting disease will be present in individuals that are found in suitable habitat, often in the midst of other affected individuals. The progression of wasting disease can be rapid, leading to death within a few days, and its effects can be devastating on sea star populations. In subtidal habitats, the sunflower star is typically the first species to succumb, followed by the rainbow star , giant pink star, giant star , mottled star , ochre star and sun star (Solaster), leather star , vermilion star , six-armed stars, and bat star . It is unknown whether the syndrome spreads sequentially from one species to the next, or if some species simply take longer to express symptoms, but the usually large populations of ochre and sunflower stars experienced massive, geographically expansive (if patchy) and well-documented declines. Other species are less abundant, so the impact of the syndrome is not as clear. Ecologists consider both sunflower and ochre stars to be keystone species because they have a disproportionately large influence on other species in their ecosystem. In fact the ochre star was the basis of the keystone species concept because of its potential to dramatically alter the rocky intertidal community in which it occurs. Our long-term monitoring data, including population estimates prior to the wasting event, in combination with our biodiversity surveys, will allow us to interpret change to communities that might result from severe population declines of the bat star. The collected information will also be used to document recovery of both sea star populations and the community affected by way of the loss of sea stars.

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