In recent years, a massive mortality event has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease event, known as ‘sea star wasting disease’ (SSWD), is linked to viral infection. In one affected sea star (
Large-scale impacts of sea star wasting disease (SSWD) on intertidal sea stars and implications for recovery
Disease outbreaks can have substantial impacts on wild populations, but the often patchy or
anecdotal evidence of these impacts impedes our ability to understand outbreak dynamics.
Recently however, a severe disease outbreak occurred in a group of very well-studied
organisms±sea stars along the west coast of North America. We analyzed nearly two
decades of data from a coordinated monitoring effort at 88 sites ranging from southern British
Columbia to San Diego, California along with 2 sites near Sitka, Alaska to better understand
the effects of sea star wasting disease (SSWD) on the keystone intertidal predator,
Pisaster ochraceus. Quantitative surveys revealed unprecedented declines of P. ochraceus
in 2014 and 2015 across nearly the entire geographic range of the species. The intensity of
the impact of SSWD was not uniform across the affected area, with proportionally greater
population declines in the southern regions relative to the north. The degree of population
decline was unrelated to pre-outbreak P. ochraceus density, although these factors have
been linked in other well-documented disease events. While elevated seawater temperatures
were not broadly linked to the initial emergence of SSWD, anomalously high seawater
temperatures in 2014 and 2015 might have exacerbated the disease's impact. Both before
and after the onset of the SSWD outbreak, we documented higher recruitment of P. ochraceus
in the north than in the south, and while some juveniles are surviving (as evidenced by
transition of recruitment pulses to larger size classes), post-SSWD survivorship is lower than during pre-SSWD periods. In hindsight, our data suggest that the SSWD event defied
prediction based on two factors found to be important in other marine disease events, sea
water temperature and population density, and illustrate the importance of surveillance of
natural populations as one element of an integrated approach to marine disease ecology.
Low levels of SSWD-symptomatic sea stars are still present throughout the impacted range, thus the outlook for population recovery is uncertain.
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- NSF-PAR ID:
- 10059217
- Date Published:
- Journal Name:
- PloS one
- ISSN:
- 1932-6203
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract The recent outbreak of Sea Star Wasting Disease (SSWD) is one of the largest marine epizootics in history, but the host-associated microbial community changes specific to disease progression have not been characterized. Here, we sampled the microbiomes of ochre sea stars,
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/https://www.doi.org/10.1371/journal.pone.0192870
