Mysterious disease creates Zombie Starfish

Sick and dying starfish (sea stars) have appeared in a multitude of locations between Alaska and southern California. 

"It's like a zombie wasteland," says biologist Emily Tucker told Nature. "You'll see detached arms crawling away from their  body."

Called Sea Star Wasting Disease, it can cause the death of an infected starfish in just a few days. Its effects can be devastating on starfish populations. 

The disease has hit before, in southern California in 1983-1984 for example and again  in 1997-98. These events were associated with warmer sea temperatures. The current outbreak is more widespread. 

It is particularly worrying because one of the starfish affected, Pisaster ochraceus, was the original "keystone species". This is a species  that has a disproportionately large effect on its environment relative to its abundance. Without it the ecosystem would be dramatically different. The concept was first proposed in 1969 using Pisaster ochraceus as a primary example.  Within a year of  _Pisaster ochraceus_  being removed, biodiversity halved.

Lesions on the animal are the first signs of the disease. Tissue then decays around the lesions which leads to break up of the body and death.

There is a map of where diseased sea-stars have been found at http://data.piscoweb.org/marine1/seastardisease.html

More information at 
http://www.eeb.ucsc.edu/pacificrockyintertidal/data-products/sea-star-wasting/index.html
http://www.nature.com/news/scientists-search-for-clues-in-sea-star-die-off-1.14370
http://news.scubatravel.co.uk/mysterious-disease-creates-zombie-starfish.html

#seastarwastingsyndrome   #starfish  

Photo credit: Steven Pavlov (CC BY-SA 3.0) 
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5 comments
 
Very useful info, thank you for posting. I realize now how important each specie is to the ecosystem especially underwater.
 
As a keystone species exactly what happens when this population collapses?  I understand that they eat mussels, clams etc but the rocky environment has a variety of starfish  but not in large numbers.
 
+Mike Weatherby _Pisaster ochraceus_ (in some areas) keeps the population of mussels down. The mussels can't colonise below a certain level as they are eaten by the starfish. This leaves this intertidal zone free for other animals and seaweeds. Otherwise mussels progress down the shore to the detriment of many other species. So a relatively small number of starfish have a big effect on their environment.
 
Well they are beautiful animals with an interesting anatomy. I hope the problem is soon solved. 
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