Pacific Rocky Intertidal Monitoring: Trends and Synthesis home

Sea Star Wasting Syndrome

Sea Star Wasting Map (as of Apr 11, 2014)     Summary Updates (as of Jan 21, 2014)

Press Release (Dec 22, 2013 PDF)

Click here to Document Observations

Click here to Collect Additional (quantitative) data

Click here for a guide to wasting symptoms in Evasterias

Click here for a guide to wasting symptoms in other sea star species

diseased pisaster ochraceus adiseased pisaster ochraceus b

Sea star wasting disease is a general description of a set of symptoms that are found in sea stars.  Typically, lesions appear in the ectoderm followed by decay of tissue surrounding the lesions, which leads to eventual fragmentation of the body and death.  A deflated appearance can precede other morphological 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 individuals that might also be affected.  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. The proximal cause of the disease, when pathological studies have been done, is typically a bacterium (vibrio), although a recent wasting event on the east coast of the United States has been attributed to a virus.  The ultimate cause is not clear although such events are often associated with warmer than typical water temperatures as was the case for the major die off in southern California in 1983-1984 and again (on a lesser scale) in 1997-98. Following the 1983-1984 event, the ochre star, Pisaster ochraceus, was virtually absent along southern California shorelines for years.

As of Summer, 2013, there is evidence that we are at the onset of another Wasting event and one that is particularly troubling because of its spatial extent. MARINe monitoring groups have documented Wasting in Pisaster ochraceus from Alaska through California (see interactive map for specific locations).  Two common attributes for many of the sites are: (1) the period prior to Wasting was characterized by warm water temperatures, and (2) the effects are dramatic. 

Sea stars and Pisaster ochraceus in particular have effects on the community that are vastly disproportionate to their abundance.  Pisaster ochraceus 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 P. ochraceus. 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.

Long-term trends in Pisaster ochraceus numbers at our monitored sites can be viewed by location here or by using our Interactive Map & Graphing Tool. Under "Long Term Graph Type" select "species counts data" and under "plot type" select "pisaster".

For more information about Sea Star Wasting Disease, please click here:

Tracking and Documenting Observations

Our research group is concentrating on:

  1. Documenting the presence of sea star wasting symptoms by means of submitted reports, our own sampling as part of MARINe Long-Term Monitoring, and our newly established Rapid Assessment Surveys of the outbreak.

  2. Developing a spatial/temporal map of the outbreak showing the location of affected populations and (when possible) the onset of symptoms for each location.  This will allow for an evaluation of potential hypotheses concerning the cause of the disease.  For example if the outbreak started from a single location its cause is likely to be different from a situation where there were multiple initiation points.

  3. Assessing the impact of the outbreak on the biological community.

Other research groups are addressing the pathology and infectiousness of wasting.  These groups include Cornell (Harvell & Hewson), University of Rhode Island (Gomez), Brown (Wessel), Western Washington University (Miner), and Seattle Aquarium.

If you are interested in adding information to our Sea Star Wasting Syndrome Map, please see the options below.

Fill out the Sea Star Disease Observation Log

Click here to submit observations through our web form. If you have any photos or spreadsheets to send, please send them here.

Please continue to submit observations after spending time diving or in the intertidal. We are constantly updating our website with the latest reports, and will update the map on a regular basis. Please remember to fill out a log even if you search and only find healthy sea stars, or no sea stars! This information is just as valuable as observations of diseased individuals.

Collect additional sea star data:

Below are the different categories that we are using to document the stage of the disease. If you are interested in collecting additional information about sea star counts, sizes, and disease categories, please contact Melissa Miner and Rani Gaddam for details. We would like to increase the number of sites where long-term sea star data are collected, but in order to ensure data consistency, it is essential that a MARINe researcher is involved with initial site set-up and sampling.

Note that data submitted to us may be used by our research group for analyses, as well as by others who submit data requests to us. If you have any concerns about this, please contact us.

Click here to download the intertidal sampling protocols (PDF).

Click here to download the subtidal sampling protocols (PDF).

Sea Star Wasting Category 1, photo a

Sea Star Wasting Category 1, photo b

Sea Star Wasting Category 2

Sea Star Wasting Category 3

Sea Star Wasting Category 4, photo a

Sea Star Wasting Category 4, photo b


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