Friday, August 08, 2014

extremely high death rates among the Purple Sea Star

English: Purple Ochre Sea Star (Pisaster ochra...
English: Purple Ochre Sea Star (Pisaster ochraceus) (Photo credit: Wikipedia)
The North American West Coast is struggling to find the answer to this mystery. Sea stars are traditionally the ‘stars’ of the show, gratifying tide poolers, snorkelers and divers with their beautiful colors and happy shapes.  But today, it would be tough to find a cluster of starfish along the coast as shown in the photo above. A mysterious wasting syndrome is killing off entire species of starfish in numbers alarming to scientists. The mass die-off was first noted in June of 2013, when scientists recorded extremely high death rates among the Purple Sea Star (Pisaster ochraceus ) populations in coastal California.  This unique ailment does not have any officially recognized causes yet, but rising water temperatures are believed to cause rapid spreading of the syndrome.
Starfish are known for their resilience; they have the ability to regenerate limbs that are damaged or dying. This wasting epidemic is sweeping so far and so fast, however, that the stars do not have a chance to regenerate. The stars develop lesions on their bodies that prevent them from grasping onto rocks, and tissue around these lesions begins to decay. The starfish try to cover the lesions and twist their arms in unnatural positions, often causing the arms to walk in different directions and tear the body apart. When the body of the sea star tears, the gonads spill out and the star dies within just a few hours. The progression of this illness can be rapid, and usually occurs in a matter of days. 

The entire pacific coastline stretching from Alaska to Mexico has experienced great loss of starfish.  Contrary to popular belief, there is no evidence linking the die-off to the Fukushima nuclear disaster in Japan, though media sources have been suggesting this link. Rather, the spread of this syndrome is partially attributed to warmer water temperatures than usual. Sea star populations do experience greater death in warm El Niño conditions, as recorded in the 1980’s and 1990’s, and the predicted 2014 El Niño may be a factor of rapid dispersion of the syndrome (though this year’s death rate is far more drastic than ever before recorded). In warmer water, dangerous microorganisms can thrive. They grow, replicate, and can infect starfish more rapidly than under normal water conditions. Scientists do surmise that the pathogen is spreading throughout the water; however, one study suggests that the pathogen may also be found in the mussels and clams that starfish eat. These food sources then infect the starfish upon ingestion. Both of these possibilities of transmission—waterborne and food borne-- require further investigation. 
Post a Comment

PyeongChang Guide - Interactive City Guide

PyeongChang  Guide - Interactive City Guide Author: R.G.Richardson All new edition with Facebook, Duckduckgo and Baidu Search. No typing, j...