Sea star

A healthy mottled sea star. The white dot on the central disc is the madreporite, not a lesion. Switgard Duesterloh photo.

Have you visited your favorite touch tank on Near Island recently? If yes, I am sure you noticed the eerie absence of one of the most common and endearing organisms that every child and many adults cherish: the sea stars. What happened to the sea stars?

Usually, when a child at the touch tank asks a question it is something innocent and simple that we have an answer to. The question about what happened to the sea stars is much larger and a lot harder to answer.

The sea stars in the touch tank have died. The same fate is affecting many of their relatives in the ocean around Kodiak. Recently, divers have reported seeing piles of dead and decomposing sea stars, while healthy and young stars are rare. The phenomenon seems to affect certain species more than others, but it is seen in several kinds of stars, including some of the more common ones: mottled stars, blood stars and sunflower stars.

We had some warning that this might be coming. Around Christmas of 2014, I wrote an article about sea star wasting disease. Back then I had a report by a researcher who had looked at sea stars from several beaches around Kodiak and found little or no evidence of sea star wasting disease.

SSWD is a condition affecting sea stars from Mexico, California, Oregon, Washington and Alaska. In fact, it is thought to be the largest ocean epidemic disease event in terms of size of geographic area affected that we have ever recorded. It was first reported from California and has killed off sea star populations along the Pacific Coast for several years now.

Last year, during a monitoring study in Kachemak Bay two researchers from the University of Alaska reported a cluster of sea stars showing the typical signs of wasting disease. The arms had patches of lesions that looked as if the star was melting. At the later stages of the disease, arms can fall off and the animal looks deflated, until it eventually dies.

In March of this year, a team from the wasting disease group of Cornell University travelled to Dutch Harbor and Kodiak to collect sea star samples. They were looking for healthy stars to establish a baseline to compare the infected stars with. They were sure their Dutch Harbor samples were healthy and they found no sick sea stars in Kodiak during their sampling. However, they mention in their blog that they already heard about reports of unhealthy sea stars from the east side of the Island.

In July, when we saw many sea stars on the beach in Old Harbor, the teacher from Washington who was with me insisted that this was sea star wasting disease we were witnessing. However, while there were certainly many dead sea stars and some deflated, also some with arms missing, I did not see the lesions and appearance of “melting away” that pictures of diseased individuals point to. Frankly, I was not sure if the Old Harbor die-off was indeed due to the arrival of sea star wasting disease on our island.

A month later the reports of sea stars dying even below the intertidal has me believing it may have been. Meanwhile, samples have been sent off to confirm if Kodiak sea stars are indeed affected by the virus that causes sea star wasting disease.

The thing is that the mysteries about sea star wasting disease are anything but unraveled. Many scientists are looking into the problem and there have been conferences on the topic. It appears there is a virus always present in diseased stars. However, the same virus can be present in stars that do not show any symptoms. Also, the virus has been known for many years, but only recently it seems to be so aggressive that there are numerous large disease outbreaks.

That leads to the suggestion that the virus acts in combination with other environmental factors to make the stars sick. We can compare this with a cold that sweeps through a school in the fall. Whether you catch it or not depends on the presence of the virus and you getting exposed to it in such large numbers that your immune system is unsuccessful in fending it off. However, the success of your immune system depends on other factors like stress, other disease, availability of the right vitamins and minerals in your system and more.

Sea star wasting disease may very well be a systemic and cumulative effect of ecosystem stressors. This means that the sea stars have too many problems to deal with and are wasting away under the combined stress of dealing with rising temperatures, ocean acidification and a virus that takes hold when their immune sytem gets overwhelmed. Of course, this is a difficult theory to prove and it will take some time before researchers can unravel some of this confusion.

This reminds me of a scene in a favorite British film episode of mine. In the scene an old man sits on a hill and watches the stars with his telescope. One by one, the stars are blinking out of existence, leaving behind only the black void of the night sky. The problem with films is that you just have to sit there and wait for the superhero to appear and solve the problems. Sadly, for now we will have to continue to study and monitor as our sea stars are blinking out of existence one by one.

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