Survey shows impact of sea star wasting disease in Salish Sea

October 26, 2016
Sea Stars from Mexico to the Pacific Northwest have been hard hit by Sea Star Wasting Disease. A survey by the UC Davis SeaDoc Society shows that in the Salish Sea, the impacts go beyond the intertidal sea stars visible from shore to animals that live below the low tide line. There are likely to be long-term impacts on these ecosystems. Credit: Joe Gaydos, SeaDoc Society

Sea star wasting disease has devastated intertidal populations of these animals on the West coast from Mexico to Alaska. But what about sea stars that live below the low tide line, mostly out of sight? An analysis of data collected by divers in the Salish Sea shows severe impacts on some species, especially the sunflower sea star, Pycnopodia helianthoides.

"Sunflower stars are major predators. This is probably going to change the shape of the ecosystem," said Joe Gaydos, wildlife veterinarian and chief scientist with the UC Davis School of Veterinary Medicine's SeaDoc Society, which carried out the analysis with colleagues from Cornell University. The findings, published Oct. 26 in the journal PLOS One, reflect anecdotal reports from elsewhere on the West coast, he said.

Sea star wasting disease broke out in 2013, causing massive death of several species of . Infected animals develop lesions that eat away tissue, with limbs dropping off as the animals die. The disease has been linked to a virus, although environmental factors may also be involved.

"The sunflower star is the most susceptible species, so we were concerned that it could be driven way down by this non-specific virus", said coauthor Drew Harvell, professor of ecology and evolutionary biology at Cornell University.

The Salish Sea, which straddles the U.S./Canadian border and includes Puget Sound and the waters east of Vancouver Island, is home to a diverse population of sea stars. The animals are important predators, eating urchins and other animals.

"The Salish Sea is known world-wide for sea star diversity, so we wanted to know, what is the impact on different species?" Gaydos said.

Sea Stars from Mexico to the Pacific Northwest have been hard hit by Sea Star Wasting Disease. A survey by the UC Davis SeaDoc Society shows that in the Salish Sea, the impacts go beyond the intertidal sea stars visible from shore to animals that live below the low tide line. There are likely to be long-term impacts on these ecosystems. Credit: Jenn Collins

The researchers used a combination of data collected by scientific divers during 2014 - 2015 and long term data collected by trained recreational scuba divers through the Reef Environmental Education Foundation (REEF).

"The REEF data were amazing. We were able to compare eight years of pre-epidemic data to the outbreak to show how devastating declines were for the sunflower stars," said Diego Montecino-Latorre, UC Davis graduate student, veterinarian and lead author on the study.

Sunflower Sea Stars Hit Hard

The results showed some species were hit hard, while others actually increased in number. Populations of sunflower sea stars dropped dramatically after the beginning of the epidemic, and several other sea star species, including the spiny pink star, Pisaster brevispinus, also declined. Numbers of the less-common leather star (Dermasterias imbricata) and two species of sea urchin, which are prey for sea stars, increased after 2013.

The virus outbreak continues, and will have lasting effects on the ecosystem. Sunflower sea stars have effectively disappeared from the Salish Sea, the study concludes. Likely as a result, numbers of urchins have increased, which in turn will lead to more browsing on kelp. Gaydos said that he and his colleagues are in discussions with the National Marine Fisheries Service to get the sunflower sea star listed as a "species of concern."

"This study revealed the need to generate a plan supporting the persistence of what used to be the most common sea star species in the Salish Sea," said Montecino-Latorre.

Explore further: Sea star death triggers ecological domino effect

More information: Montecino-Latorre D, Eisenlord ME, Turner M, Yoshioka R, Harvell CD, Pattengill-Semmens CV, et al. (2016) Devastating Transboundary Impacts of Sea Star Wasting Disease on Subtidal Asteroids. PLoS ONE 11(10): e0163190. DOI: 10.1371/journal.pone.0163190

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Gavilan
not rated yet Oct 26, 2016
Henry's Law and the Ocean – Atmosphere System.

Although closely related, could ocean and atmospheric de-oxygenation be a more time critical issue than climate change?

The Scripps O2 Program website indicates a slight worldwide decrease in atmospheric O2 concentrations over the past few decades.

The oxygen concentration window for most terrestrial life is quite small; that window is much smaller for oxygen dependent aquatic life. Any changes in atmospheric O2 concentration would have significant impact on the ocean ecosystem.

It can be inferred that some measure of O2 was "stored" as ocean solute when atmosphere O2 levels were somewhat higher than in this emerging Anthropocene; and any measurable reduction in atmospheric O2 concentration would mean dissolved oxygen in the ocean would come out of solution, thus depleting Ocean O2 solute in accordance with Henry's Gas Law.

Is atmospheric de-oxygenation depleting ocean solute?
humy
not rated yet Nov 03, 2016

Although closely related, could ocean and atmospheric de-oxygenation be a more time critical issue than climate change?

There is currently no noteworthy atmospheric de-oxygenation taking place so that is totally a non-issue.

As for ocean de-oxygenation, it is only a problem locally in some parts of the ocean where there has been dumped so much sewage (and sometimes other organic waste) that the bacteria that feed on the waste have locally removed all the devolved oxygen from the water. Although this is always a very serious local problem (kills nearly all local marine life), it has little effect on the global ocean as a whole and its effects can be easily reversed over a few years simply by stop dumping such waste into the ocean. So I would say climate change is by far the more important issue.
humy
not rated yet Nov 03, 2016
The Scripps O2 Program website indicates a slight worldwide decrease in atmospheric O2 concentrations over the past few decades.

The operative word there is "slight"; it is so slight its a non-issue and nothing to be concerned about. We are talking about much less than 0.1% reduction of all the oxygen in the atmosphere. Even a whole 0.1% reduction of all the oxygen in the atmosphere will have no measurable impact on life.


Is atmospheric de-oxygenation depleting ocean solute?

Not by any measurable amount. Local oxygenation of ocean water is not caused by atmospheric de-oxygenation, which is so minute as to have no impact at all, but rather from sewage being dumped locally into the ocean.
humy
not rated yet Nov 03, 2016
misprints: "devolved" should have been "dissolved" in:
... that the bacteria that feed on the waste have locally removed all the devolved oxygen from ...


and "oxygenation" should be "de-oxygenation " in;

Local oxygenation of ocean water ...

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