Wednesday, April 22, 2015

Sea Star Wasting Disease Update

A survey of Constellation Marine Reserve in West Seattle on April 20th 2015 results:
Pisaster ochraceus (Purple Sea Star)   41 healthy - 5 with SSWD
Pycnopodia helianthoides  (Sunflower Star)   1 small (damaged likely by gull) otherwise healthy
Evasterias troschelii (Mottled Star) None observed
No other sea stars observed.
Tide Level:   minus 1.7ft  at 12:45PM
Surface temp:   63 deg f.
Wind - N, light
Clear and sunny
The count included all of Constellation Marine Reserve down to the minus 1.7ft tide level.
Much of the beach was covered with an extensive growth of seaweeds, especially Wire Weed and various kelps.  So some sea stars may not have been visible.  The survey only included sea stars that were easily visible without turning over seaweeds or rocks.  Previous surveys have been done in the same manner.  Last year appeared to be a good year for sea star recruitment and many were seen over the Winter and most appeared healthy.  In Spring the juvenile stars go into hiding under rocks and crevasses where they cannot be seen so it is difficult to access the population of juvenile stars during the Spring and Summer.  The question is:  Will these juvenile stars remain healthy or contract SSWD?  We will likely not know the full answer to that for a few years.  All of the Purple Stars observed on April 20th were medium to large size as in the images.
The highest count of Pisaster ochraceus  at Constellation Marine Reserve was in August of 2011   -  609  (prior to SSWD). 
Sunflower Star (small) with damage (likely due to gull)

Purple Sea Star with SSWD

Purple Sea Star (healthy appearing)

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