Did you know about the species of sea star in our waters that releases slime to deter predators?
Slime stars are so wickedly adapted! Their distinctive puffy bodies have led to them also being known as Cushion Stars.
They release a LOT of thick, transparent goo from their upper surface when disturbed.
Disturbance constitutes rough handling, temperature shock or when other sea star species try to eat them. Sunflower Stars and Morning Sun Stars are known to trigger the slime production and get a mouthful of goo. The mucus is reported to be toxic to other invertebrates if they are immersed in it for 24 hours.
How much mucus do Slime Stars produce? See the Hakai Institute’s video below.
What is also so unique about Slime Stars is that they “exhale” water through that big pore in their upper surface every few minutes (the osculum). The full “exhalation” of the water takes about 5 seconds. You can see in the photos and video below how wide the hole opens. Water enters the sea star on the underside (through ambulacral grooves).
The tips of the arms / rays of Slime Stars are also distinctive. See how they curl upward? That is believed to be an adaptation to hold the mucus on the upper surface of the sea star.
See how the tips of the rays are curled upward?
As a result of genetic research, it has been put forward that the individuals with dark markings may be a distinct species from the solid-coloured ones. Currently, they are all classified as Pteraster tesselatus.
– Maximum size: 24 cm across. – Known range: Bering Sea to Washington State; from 6 to 436 meters. – Diet: Sponges, tunicates, and bivalves such as the False Jingle.
See the juvenile here to the right of my buddy Natasha? There, right beside the mating Yellow-Rimmed Nudibranchs. This Sunflower Star was in just 5 metres of water.
Today’s two Sunflower Stars are the first I have seen in twelve hours underwater over the last three months and believe me, I have been looking. I only saw one before that. They are such a rarity now. Will these two survive? I have seen waves of juveniles before and then they disappear. Their plight appears to be linked to climate change.
Hope? With action . . . yes, there is shining hope.
Without action . . . no.
Please hang in there. Please read on.
I have been struggling too, looking for escape / reprieve from global realities as another “atmospheric river” is forecast to fall on parts of our province. It is so tempting to want to hide especially if we see the problems we are facing as disparate. They are not.
I have had to remind myself of the common solutions so that I see a way forward that is not guided by the faintness of blind hope; paralyzed by fear and overwhelm; and / or obfuscated by the din of values and voices that serve the few for a brief time.
Common solutions include: to know, live and share the GAINS that come from using LESS (fossil fuels, dangerous chemicals, disposables, less consumerism generally); to speak for truth and science and to have compassion for those who cannot; to exercise our power as voters and consumers to serve future generations; and to care and act on the knowledge of connection to others – across time, cultures, distance, and species.
In short, it’s a really good time to be a good human.
I had to dig for these words for myself. As always, may they serve you too.
The same juvenile Sunflower Star a few minutes earlier. Notice the fish? There’s a Painted Greenling on the left and a Blackeye Goby on the right.
For those who are not yet aware, I include the reality of Sea Star Wasting Disease (SSWD) below. A link to a summary of the research and where to report sightings is in my blog at this link.
The other Sunflower Star we saw yesterday.
Since 2013, more than 20 species of sea star have been impacted by SSWD from Mexico to Alaska. There is local variation in intensity of the disease and which species are impacted. It is one of the largest wildlife die-off events in recorded history. Sea stars contort, have lesions, shed arms, and become piles of decay.
Currently, some species of sea star appear to have recovered while others remain very heavily impacted. Sunflower Stars (Pycnopodia helianthoides) have been devastated and were added to the International Union for Conservation of Nature (IUCN) list as Critically Endangered. There are current efforts to have Sunflower Stars assessed by the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with hopes that they receive protection under Canada’s Species at Risk Act.
There is NOT scientific consensus about the cause. Current hypotheses focus on (i) a virus and (ii) low oxygen at the surface of the sea star’s skin maintained due to bacteria. What is consistent in is that changing environmental conditions appear to allow the pathogen (be it bacteria or viruses) to have a greater impact.
The best current source for a summary of the research is Hamilton et al (August, 2021). From that source: ” . . . outbreak severity may stem from an interaction between disease severity and warmer waters” and “Though we lack a mechanistic understanding of whether temperature or climate change triggered the SSWD outbreak, this study adds to existing evidence that the speed and severity of SSWD are greater in warmer waters”.
What I believe to be the reality off the coast of British Columbia is that there are refuges of Sunflower Stars at depth where it is colder. They spawn with some young then settling in the shallows where they may succumb to the pathogen if stressed by warmer water.
Close up on the second Sunflower Star. This one was at about 20 metres depth.
Diversity matters. Language matters. I suspect you agree. ☺️
In this case it’s about sea stars. I am sharing with you because you are an important audience to help increase understanding.
Just off our coast, there are 31 species of sea star in the Class “Asteroidea”. I hope my compilation below gives a sense of that diversity. The photos are all of different species photographed by yours truly off NE Vancouver Island.
Yet, even major news outlets have reported on sea stars as if they are all ONE species (includes CBS and Phys.org).
Thirteen species in the above compilation from left to right: Top row: Vermillion Star (Mediaster aequalis), Morning Sun Star (Solaster dawsoni), Rose Star (Crossaster papposus). Second row: Leather Star (Dermasterias imbricata), Ochre Star (Pisaster ochraceus), Orange Sun Star (Solaster sp. A = undescribed species). Middle: Sunflower Star (Pycnopodia helianthoides). Third row: Bat Star (Patiria miniata), Painted Star (Orthasterias koehleri), Drab Six-Armed Star (Leptasterias hexactis). Bottom row: Spiny Red Star (Hippasteria phrygiana), Velcro Star (Stylasterias forreri), Striped Sun Star (Solaster stimpsoni).
Why does this matter?
Not only do different species of sea star have different ecological niches, but communication about them as if they are one species has greatly confounded the understanding of what is happening with Sea Star Wasting Disease (SSWD). When a few individuals of one species are seen, this has been extrapolated to text like “But now, the species is rebounding.”
Which species? Where? Did the individuals survive?
This sort of “collective” perception is also often reflected in comments on my social media posts. When I post about any sea star species, comments like the following often result: “Good to see “THE sea stars” are coming back.”
Yes, some species appear to be doing better since the onslaught of SSWD beginning in 2013 e.g. Ochre Stars. Other species do not appear to have been impacted much at all e.g. Blood Stars. But the world’s biggest species – the Sunflower Stars who help maintain kelp forests – are now recognized as Critically Endangered by the International Union for Conservation of Nature (see further information below).
The odds are already stacked against the appropriate learning about the conditions causing SSWD because it is happening in the dark, below the surface.
Blurring this group of extraordinary starred animals into all being the same, risks an even greater loss of understanding, colour, diversity . . . and action. 💙
Further content about the IUCN designation from my post on social media:
It’s official and so important to know. The iconic, world’s largest sea star species, the Sunflower Star, has now been added to the International Union for Conservation of Nature (IUCN) list as Critically Endangered.
This is no surprise to those of us who have been monitoring their health but to many, Sea Star Wasting Disease is unknown, even though it is one of the biggest known wildlife die offs in recorded history.
It has happened largely out of sight, beneath the Ocean’s surface. Further, there are many of us who do not have enough understanding / appreciation of (1) the connection between land and sea and; (2) the different sea star species and their ecological importance. Seeing sea stars of other species does not mean that all species are okay. Sunflower Stars (Pycnopodia helianthoides) definitely are not.
It is positive that they have been officially “listed”. With this recognition of how at risk they are, there is better potential for resources and action to find out what has caused the die off and what this might be indicating about changing environmental conditions. There is the hope that more people will care.
This is an international designation. The species also needs to be assessed in Canada to determine “status” and potential protection / action under the federal Species at Risk Act.
“Populations . . . experienced dramatic crashes in response to a marine wildlife epidemic event – referred to as sea star wasting syndrome – that began in 2013. Using over 61,000 surveys from 31 datasets, The Nature Conservancy and expert ecologists at Oregon State University calculated a 90.6% decline in the global population of sunflower sea stars due to the outbreak and estimated that as many as 5.75 billion animals died from the disease . . . “The rapid decline of this giant sea star, and of the sea kelp forests that it helps preserve, highlights the importance of every single species on the IUCN Red List of Threatened SpeciesTM. Its entry into the IUCN Red List in the highest threatened category emphasizes the need for urgent action to understand and combat the wasting disease that is sweeping through the population. We hope that this listing leads to positive action and recovery for this species and its ecosystem,” said Caroline Pollock, Programme Officer for the IUCN Red List Unit. Sunflower sea stars are now nearly absent in the contiguous United States and Mexico. No stars have been observed in Mexico since 2016, none in California since 2018, and only a handful in the outer coasts of Oregon and Washington since 2018. They are still present in Puget Sound, British Columbia, and Alaska, but only at a fraction of their former population in most places.”
[If you are coming here from Instagram, please see this linkfor background on Sea Star Wasting and where to report sightings.]
Endangered? I gasped when I saw this adult Sunflower Star on my last dive and hung nearby for a little while. I found myself thinking in a way that could be interpreted as prayer.
Did you realize Sunflower Stars are now so rare – these giants that should be abundant on the coast from Alaska to Mexico?
Endangered? Many of us who have been monitoring Sea Star Wasting Disease since 2013 certainly think so andthere is a campaign in Washington State to have them recognized as such.
There has been such misunderstanding and “ocean blindness” about what has been going on. Even reputable news outlets have put into the world information about the Disease that speaks of sea stars as if they were one species and hence, if some sea stars are sighted, well then everything is fine.
It’s not fine. At least 20 species of sea star have been impacted by Sea Star Wasting Disease. Some are recovering well but . . . this the world’s largest sea star species, the Sunflower Star, Pycnopodia helianthoides, is NOT.
We sometimes see waves of juveniles, maybe resulting from more adults being at depth who are close together enough that when they broadcast spawn, fertilization results (broadcast spawning is when males and females release their sex cells into the water on cue). But, ultimately these juveniles disappear.
Sea Star Wasting Disease (SSWD) is the largest wildlife die off in recorded history. That be truth. But because it is happening below the surface there is less engagement, funding, and knowledge.
Does it matter? Yes, it matters a lot, ecologically and with regard to what the Disease may teach us.
Sunflower Stars have a similar ecological niche to Sea Otters re. grazing on urchins and maintaining kelp forests (see video below). You know that if Sea Otters were dying en masse we would certainly be engaged, invest in research, and want knowledge.
Why would a virus that is not new be able to have a greater impact? Due to stressors and yes, these are believed to be related to climate change.
To those wonderfully engaged humans who have read all of this, please know this is not an additional problem that requires novel solutions. You are the last people who I wish to burden, you who care as you do. The plight of Sunflower Stars is a symptom of what is the same set of problems re. short term economies, absence of precaution, fossil fuel use, and consumerism.
Reporting sightings? I have reported the sighting of this lone, adult Sunflower Star to add to the knowledge of the impacts of SSWD. Citizen science is so important to understanding. Further information on the Disease and where to report sightings of sea stars can be in my blog at this link.
And to you dear Sunflower Star,
May you find another of your kind for the sake of biodiversity, ecology, human learning and understanding, and so that your species will not disappear from children’s drawings of life on our coast.
May it not be that we continue on a path where Sunflower Stars slip away from our memories, or that we end up talking to children about “There used to be these giant, colourful sea stars . . .”
💙
Sighting was made on June 15th, near Port McNeill.
Video below re. Sea Star Wasting Disease and ecological impacts.
Rose Stars have such diversity in colour and pattern, that the species is also known as the “Snowflake Star”; a name suggesting that no two are alike.
Am I trying to make some sort of point as it applies much more broadly? Why, whatever would make you think that? 😉
Surely we humans rejoice in the beauty of diversity?
Notice that above this Rose Star, there is another local, marine ambassador for diversity of colour within a species.See the Blue-Line Chiton (Tonicella undocaerulea)?
Please see additional photos (and slideshow) below to get a further sense of the diversity, the beauty, and the perfection.
Species information:
Crossaster papposus to 34 cm but in British Columbia the maximum size is believed to be 17 cm.
They can live to at least age 20. Species is slow growing. Maximum size is reached around age 10.
Even the number of arms varies. Most Rose Stars have 11 arms but number ranges from 8 to 16. From personal communication with zoologist Neil McDaniel: ” I did counts of 63 images I had on file [all from British Columbia’ and nearly 90% (87%) had 11 arms, about 10% had 10 and 3% had 12.”
They are SPEEDY! Zoologist Neil McDaniel clocked them at 50 cm/min. Larger individuals were documented to travel over 5 meters in 12 hours. They are serious predators but may also be speedy because they are known to be prey for Sunflower Stars and Morning Sun Stars.
Diet is known to include sea pens, nudibranchs, bryozoans, bivalves (e.g. clams), juvenile urchins and tunicates. Their diet is likely broader than this as they are not picky eaters. I often see them in rocky habitats covered by coralline algae species (see photo below) and believe that is, at least in part, because the prey there include Orange Social Tunicates. They are one of the few species of sea star known to feed on nudibranchs. They also are known to have attacked other sea star species – Mottled Stars and Six-rayed Stars
How they feed: When they feel their prey, and are hungry, they retract their sensory tube feet (tube feet at the tips of their arms), and then stretch up on their tippy toes (extending their terminal tube feet) to be higher and able to “pounce” on their prey when on the ocean bottom. Smaller prey are swallowed whole. Larger prey are held with the tube feet and, as is the case with other sea star species too, they evert their stomach OUT OF THEIR BODIES and into or over their prey.
Research supports that Rose Stars can sense potential prey and other sea stars by smell (distance chemoreception).
In the photos below you will also see the intricacy of the surface of sea stars. You will see:
Spines
Pedicellaria = amazing little structures that can nip off the tube feet of other species of sea star e.g. the predatory Morning Sun Star (Solaster dawsoni).
The tufts are “papulae”. They are the gills / respiratory organs of the sea star. They can retract into the surface of the sea star’s body.
Range: Bering Sea to Puget Sound; Arctic Ocean, North Atlantic Ocean, North Sea, western Baltic Sea.
Depth: Found from the shallows of the intertidal to ~1,200 m. Believed to more often be in low current areas.
I saw little impact on this species from Sea Star Wasting Disease around NE Vancouver Island BUT Rose Stars were hit very badly in 2014 in other areas e.g. Sechelt Inlet, British Columbia (McDaniel, pers. comm.). See photo at the end of the blog. The species seems to be rebounding, unlikely Sunflower Stars which remain devastated across their range.
Rose Star and retracted Orange Zoanthids. Some are likely being snacked upon.
Very typical habitat for where I find Rose Stars. I believe their prey on these coralline algae covered rocks include the small orange animals you see = Orange Social Tunicates. Notice too that there is another Blue-Line Chiton.
The lineage of “feather stars” (members of the crinoid class) goes back 485 million years, give or take a million. They crawl around. They swim in the most extraordinary way. You’ll see. 🙂
Another non-scientific name used for feather stars is “sea lilies” but I avoid that. As pretty as the name is, I believe it adds to confusion. These are animals, not plants. They are echinoderms, relatives to sea stars, brittle stars, sea urchins and sea cucumbers. Also “sea lily” is a name more often used for the crinoid relatives that have a stalk into adulthood. Only juvenile feather stars have a stalk. Then, get this . . . they detach and crawl down their own stalk to perch directly on the bottom! (Source: A Snail’s Odyssey). See below.
There are many feather star species in the world but the detail here is about the species commonly found in shallow water off the coast of British Columbia – Florometra serratissima (range is from the Aleutian Islands to Baja California).
Feather stars have 5 feathery arms that split to form 10 or more arm branches that are used to gather bits of organic matter (snacks) out of the water. With arm’s outreached, Florometra serratissima is up to 25 cm wide and they are up to 31 cm tall. Feather stars also use their arms to swim as recently captured in this video by dive buddy, Brenda Irving. They swim as if “walking up an invisible staircase” (quote from Lamb and Handby).
Phenomenal – right?
The following detail on their locomotion is largely compiled from the brilliant resource “A Snail’s Odyssey“ by Tom Carefoot, Professor Emeritus, Department of Zoology, University of British Columbia.
How do they swim?
“Florometra serratissima is the only swimming species of crinoid on the west coast of North America. It swims by graceful undulation of its arms in 3 sets, each set moving successively but overlapping. Thus, while about one-third of the arms are in power stroke, another third are in recovery, and the last third somewhere in between. During the power stroke the arms extend out maximally for greatest frictional resistance, while during the recovery stroke they bend inwards to minimise resistance.”
“The sets comprise two triplets and one quadruplet, are their composition with respect to specific arms is invariable (see sequence below). In the scenario shown, swimming is initiated by the blue triplet making a downstroke, followed 1sec later by the green quadruplet, and 2 seconds later by the orange triplet. An entire sequence is completed, then, in about 3 seconds, and the pattern may be repeated for up to 30 seconds.” (Source: A Snail’s Odyssey).
After several strokes to move vertically (to a mean height of 29 cm at an average speed of 5.4 cm/sec), individuals often turn 90 degrees and swim horizontally. If there is current, they will swim with the current. Horizontal swimming is achieved by the 5 arms furthest away from the bottom making stronger downward pulses than the arms closest to the bottom. (Source: Shaw and Fontaine. See Figure 3 at this link if you wish to better understand the horizontal movement).
Swim speed was found to occur in “short, repeatable bursts of 10 to 30 seconds. Continuous swimming beyond 4 minutes provokes a refractory period lasting 5 to 17 minutes during which individuals are incapable of swimming.” (Source: Shaw and Fontaine).
Feather stars end up back on the ocean bottom by stopping movement, and then “parachuting” down (as can be seen at the end of the video above).
Swimming and crawling can be stimulated by current and touch from predators such as Sunflower Stars (Pycnopodia helianthoides) and crabs. Research supports that if touched by a Sunflower Star, there is about a 5 second delay followed by “several power strokes carrying the stimulated individual 1 to 3 metres away. This cycle can be repeated several times and capture by a sea star is actually thought to be rare.” (Source: A Snail’s Odyssey).
Crawling has been found to be feather stars’ main means of getting around with swimming being only in response to a predator or touch.
“Stalkless crinoids such as Florometra serratissima anchor to the substratum [ocean bottom] using flexible cirri [these have been described as holding on like bird’s feet do]. The cirri are jointed and can slowly bend and straighten. . . . ” (Source: A Snail’s Odyssey).
The arms are also involved in crawling around. The 10 arms attach to the bottom with small hooks, the central part of the feather star’s body (the calyx and cirri) is lifted. “The arms then contract and extend on opposite sides of the body, which moves it in one direction or the other. Repetition of this behaviour will gradually move the individual to a new location.” (Source: A Snail’s Odyssey)
What a remarkable species with relatives dating back 485 million years and defences including: (1) being able to regenerate arms; (2) having a body that has little nutritional content, is hard, and may taste bad AND; (3) is strong enough to withstand the current that delivers snacks, but light enough to allow swimming as an escape response.
Above: This remarkable photo by Neil McDaniel shows an individual with eggs (orange) and allows you to see the incredible fine details of the “feathers” – the pinnules of Florometra serratissima.
Above: Another fantastic capture by Neil McDaniel. Florometra serratissima climbing down his/her stalk to live an an adult, moving around on its cirri and swimming.
Round Lipped Boot Sponge (1 m tall) near Powell River, festooned with feather stars (Florometra serratissima). Also, see the juvenile Giant Sea Cucumbers?
Above: Dive buddy, Brenda Irving, just before taking the video above. Here with the coral Primnoa pacifica which is usually found at great depth but the upwellings at this site in Knight Inlet lead to it occurring much shallower too, up to ~15 m. The animals on the coral in this image are Orange Hermit Crabs. Detail on this species of coral and this extraordinary site can be read at “A Proposal to Create a Marine Refuge at the Knight Inlet Sill, British Columbia to Protect Unique Gorgonian Coral Habitat” by Neil McDaniel. Click here.
[Update: November 18, 2014 Study published today – cause of Sea Star Wasting Syndrome a densovirus that has been present for at least 72 years? Why has it led to mass mortality now? What makes sense is that, like any virus, the incidents of “pathogenicity” depends on stressors (e.g. temperature change) and proximity of individuals. The virus has also been found in other echinoderms like urchins and sand dollars and it persists in sediment = can be transmitted by those vectors and there is the potential that the other echinoderms are/will be affected. See the study by Cornell University at the link below (lead author Ian Hewson). Includes “If SSaDV is the cause of the current SSWD event, it is unclear why the virus did not elicit wide disease outbreaks in the past during periods in which it was detected; however, there are several possible reasons why the current SSWD event is broader and more intense than previous occurrences. SSaDV may have been present at lower prevalence for decades and only became an epidemic recently due to unmeasured environmental factors not present in previous years that affect animal susceptibility or enhance transmission.” http://www.pnas.org/content/early/2014/11/12/1416625111.abstract]
I am very sad to report that Sea Star Wasting Syndrome is now on NE Vancouver Island.
I first detected symptoms of the Syndrome at Bear Cove in Port Hardy on December 13th. Please see table at the end of this blog for how the species affected appears to be quite different from further to the south. Leather stars seem particularly affected and the Syndrome appears to advance much more slowly.
I have tried to think up a terrestrial analogy for what is happening to the sea stars so that non-divers might better get a sense of the weight and ecosystem importance of it. However, I can’t come up with a good terrestrial equivalent of an abundant group of highly visible, apex predators. My best attempt is to suggest you think of sea stars like birds of prey. Imagine what you would feel like if you were to notice they were dying, bodies deflating . . . then melting away and that this would progress very quickly and spread like wildfire.
The meltdown of sea stars was first detected in June 2013 in Washington State in ochre stars and in sunflower stars in Howe Sound (BC) in late August 2013 but has now been reported at sites from Alaska to the Mexican border.
The number of sea stars impacted is orders of magnitude greater than any previous known outbreak.
Most likely due to a pathogen (virus and or/bacteria). Cornell University is doing the genomic work. Toxins and environmental conditions have not been ruled out as the cause (or compounding factors).
If it is a pathogen, how quickly it spreads is influenced by the number of animals and if they are stressed. There are likely to be layers of stressors.
It has put forward by the scientific community that this could be a normal mechanism for overpopulation in sea stars.
While radioactivity certainly is an environmental stressor, the Fukushima Disaster has not been implicated in Sea Star Wasting Syndrome – really! From a January 30, 2014 Earth Fix article “scientists see Fukushima as an unlikely culprit because the die-offs are patchy, popping up in certain places like Seattle and Santa Barbara and not in others, such as coastal Oregon, where wasting has only been reported at one location.” (Also see January 19th, 2014 article “Half-Lives and Half-Truths – Discovering the truth about five of the most widespread myths of the Fukushima disaster” and scroll to the sources at the end of this article for scientific papers on the potential impacts of Fukushima).
The 1-minute time-lapse video below shows the progression of the Syndrome in a sunflower star over 7 hours.
Yep, it’s terrible.
However, I believe very strongly that, in attempting to raise awareness about marine environmental issues, I must always reflect on “what you can do”. If I do not, I contribute to the spread of a devastating human syndrome: Eco-paralysis. Symptoms include people becoming despondent, overwhelmed, and underactive in undertaking positive socio-environmental change, and often saying “It’s all hopeless”. The cause? This I do know. Eco-paralysis is the result of not seeing the common solutions between environmental problems.
Sea Star Wasting Syndrome is a solid indicator of how little we know about our life-sustaining oceans. It emphasizes the importance of humility and precaution in decision-making around the environment and how we are all empowered to reduce environmental stressors (with emphasis on reducing fossil fuel consumption and chemical use).
Having witnessed what I have over the last many weeks, I am all the more driven to assist others in (1) falling deeper in love with the NE Pacific Ocean by revealing the beauty below her surface and (2) feeling the joy that comes from creating change that is better for the environment and, therefore, ourselves.
Where to relay sea star data (of great value in understanding the survival, species impacted, range, and potentially, contributing factors of Sea Star Wasting Syndrome:
Sunflower Stars are already recognized as Critically Endangered by the International Union for Conservation of Nature but this does not offer them protection in Canada or the US. In Canada, an “unsolicited assessment” has been provided to the Committee on the Status on Endangered Wildlife in Canada (COSEWIC) in hopes of expediting the protection of Sunflower Stars under Canada’s Species at Risk Act.
The March 15 announcement by NOAA includes: “While Sea Star Wasting Syndrome is not well understood, it appears to be exacerbated by rapid changes in water temperature, warmer ocean temperatures, and other physical stressors. Outbreaks are likely to recur as the climate continues to warm. Outbreaks may also be more frequent or spread more quickly . . . Populations of the species appear relatively more viable are in cooler, and possibly deeper, waters to the north, including Alaska, British Columbia, and the Salish Sea in the Pacific Northwest. Losses due to the syndrome in these waters were not as high as in more southerly waters.”
December 2022: Roadmap to recovery for the sunflower sea star (Pycnopodia helianthoides) along the west coast of North America. The Nature Conservancy (Heady et al). From the Executive Summary:
“A sea star wasting disease (SSWD) event beginning in 2013 reduced the global population of sunflower sea stars by an estimated ninety-four percent, triggering the International Union for the Conservation of Nature (IUCN) to classify the species as Critically Endangered. Declines of ninety-nine to one hundred percent were estimated in the outer coast waters of Baja California, California, Oregon, and Washington. From the Salish Sea to the Gulf of Alaska, declines were greater than eighty-seven percent; however, there is uncertainty in estimates from Alaska due to limited sampling. A range-wide species distribution analysis showed that the importance of temperature in predicting sunflower sea star distribution rose over fourfold following the SSWD outbreak, suggesting latitudinal variation in outbreak severity may stem from an interaction between disease severity and warm waters. Given the widespread, rapid, and severe declines of sunflower sea stars, the continued mortality from persistent SSWD, and the potential for the disease to intensify in a warming future ocean, there is a need for a Roadmap to Recovery to guide scientists and conservationists as they aid the recovery of this Critically Endangered species . . . The area of greatest concern and need for immediate action common to all geographic regions is understanding disease prevalence and disease risk. Here we use the term “disease” to describe SSWD, also known as Sea Star Wasting Syndrome or Asteroid Idiopathic Wasting Syndrome, which affects some twenty species of sea stars and the cause(s) of which remain unknown and under debate in the literature. Much work is needed to improve our understanding of SSWD, the cause(s) of SSWD, how SSWD impacts wild sunflower sea stars, SSWD dynamics in a multi-host system, and to discover and develop measures to mitigate SSWD impacts and risks associated with conservation actions.”
Sea Star Wasting Disease (SSWD) – summary of current state of knowledge
Since 2013, more than twenty species of sea star have been impacted by SSWD from Mexico to Alaska. There is local variation in intensity of the disease and which species are impacted. It is one of the largest wildlife die-off events in recorded history. Sea stars contort, have lesions, shed arms and become piles of decay (see below for photos and detail about the progression of the disease).
There is NOT scientific consensus about the cause. Current hypotheses focus on (i) a virus and (ii) low oxygen at the surface of the sea star’s skin maintained due to bacteria. What is consistent in is that changing environmental conditions appear to allow the pathogen (be it bacteria or viruses) to have a greater impact.
The best current source for a summary of the research is Hamilton et al (August, 2021). From that source: ” . . . outbreak severity may stem from an interaction between disease severity and warmer waters” and “Though we lack a mechanistic understanding of whether temperature or climate change triggered the SSWD outbreak, this study adds to existing evidence that the speed and severity of SSWD are greater in warmer waters”.
As with any pathogen (like the flu virus), the expression of a pathogen as disease is influenced by the number and proximity of individuals i.e. more animals together leads to faster spread of the virus and/or bacteria.
Currently, some species of sea star appear to be recovering while others remain very heavily impacted. Sunflower Stars (Pycnopodia helianthoides) have been devastated and were added to the International Union for Conservation of Nature (IUCN) list as Critically Endangered on December 10th, 2020. There are current efforts in both Canada and the USA to have the species assessed and protected. In Canada an assessment will be delivered to the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) with hopes that they receive protection under Canada’s Species at Risk Act. In the United States, feedback is current being requested (to February 25, 2022) and whereby Sunflower Stars may receive protection under the Endangered Species Act.
See the media release from the Nature Conservancy “Iconic Sea Star Listed Critically Endangered After Study Finds Marine Epidemic Event Nearly Wiped Out Global Population” at this link.
There has been much recent media coverage on how Sunflower Stars are being bred in captivity. While such efforts are of course to be applauded and are part of the research needed to understand / mitigate Sea Star Wasting Syndrome, the inclination of the media to put this forward as the solution is troublesome. If the pathogen causing Sea Star Wasting Syndrome is not known, and the stressors related to climate change continue, releasing these Sunflower Stars into the Ocean would expose them to the same stressors as those who died.
Sunflower Stars are of great ecological importance in maintaining kelp forests. Research published by Burt et al in 2018 quantifies the importance of Sunflower Stars in maintaining kelp forests. Sunflower Stars feed on Green Urchins which graze on kelp. Findings included that the decline of Sunflower Stars “corresponded to a 311% increase in medium urchins and a 30% decline in kelp densities”. The loss of kelp forests can impact many other ecologically and commercially important species that relay upon them as habitat and food. Note too that our reliance on kelp forests includes oxygen production and carbon dioxide buffering.
From Hamilton et al (August, 2021): “The aetiological agent(s) driving SSWD remain unidentified. Current hypotheses focus on (i) a viral-sized aetiological agent (e.g. sea star-associated densovirus) and (ii) low oxygen at the surface of the skin maintained through subsequent bacterial proliferation [7,15]. Additionally, the relationship between temperature and SSWD is unresolved. In laboratory studies, the lesion growth rate increased with increasing temperature, but evidence for warm temperatures triggering SSWD is mixed [16–18]. Some studies showed a positive relationship between the timing of the outbreak and temperature [6,18,19], while others found no relationship [8,20] or a negative relationship [21]. Differences in disease detection could explain these variable field observations. SSWD is a fast-paced disease accelerating at the scale of weeks to months, so peak prevalence of infection is difficult to detect from seasonal or annual monitoring programmes [7]. Thus, the relationship between environmental triggers of an outbreak can easily be confounded with pandemic disease dynamics [22] . . . Additionally, whether climate change or warm temperatures triggered the outbreak remains unknown. Harvell et al. [6] showed that warm temperature anomalies explained more than a third of the variance in Pycnopodia outbreak timing in the Salish Sea [6]. Furthermore, Aalto et al. [19] modelled the initial outbreak spread dynamics and suggested that warm temperatures can trigger disease and increase mortality [19]. Conversely, several studies found that warmer ocean temperatures were not associated with SSWD outbreak timing in Pisaster ochraceus in Oregon and California [8,21]. Though we lack a mechanistic understanding of whether temperature or climate change triggered the SSWD outbreak, this study adds to existing evidence that the speed and severity of SSWD are greater in warmer waters.”
Research on Sea Star Wasting Syndrome in reverse chronological order.
Best current summary of research is the December 29, 2021 assessment report for the International Union for the Conservation of Nature = Gravem, S.A., W.N. Heady, V.R. Saccomanno, K.F. Alvstad, A.L.M. Gehman, T.N. Frierson and S.L. Hamilton. 2021. Pycnopodia helianthoides. IUCN Red List of Threatened Species 2021.
Why share this information? It is often marine species that testify to environmental problems first, serving as indicators for the resources upon which we too depend. The hypothesis remains that the sea stars have succumbed in an unprecedented way because of changed ocean conditions (stressors). Too few of us realize the importance of sea stars in the ocean food web (see video below) let alone the importance of what they might be indicated about environmental health.
Quote from Drew Harvell, Cornell University professor of ecology and evolutionary biology who studies marine diseases: “these kinds of events are sentinels of change. When you get an event like this, I think everybody will say it’s an extreme event and it’s pretty important to figure out what’s going on . . . Not knowing is scary . . . If a similar thing were happening to humans, the Centers for Disease Control and Prevention would commit an army of doctors and scientists to unraveling the mystery.”
Below, January 30, 2019 video by the Hakai Institute re. Sunflower Stars and Sea Star Wasting Disease.
Further detail on recent research
Research published on January 6th, 2021 (Aquino et al) suggests that the pathogen is not a virus but a bacteria but, again, there is not scientific consensus about this. The research puts forward that warmer oceans and increased organic matter appear to lead to increases in specific bacteria (copiotrophs) that then use up the oxygen at the interface of the sea star and the bacteria, and the sea stars can’t breathe. The hypothesis includes that “more heavily affected species were rougher and therefore had a much larger boundary layer (the layer at the animal-water interface) than those species which were less affected.”
October 21, 2019 – Research by Rogers-Bennet and Catton published in Scientific Reports on Bull Kelp deforestation off the coast of Northern California – Marine heat wave and multiple stressors tip bull kelp forest to sea urchin barrens. Abstract: “Extreme climatic events have recently impacted marine ecosystems around the world, including foundation species such as corals and kelps. Here, we describe the rapid climate-driven catastrophic shift in 2014 from a previously robust kelp forest to unproductive large scale urchin barrens in northern California. Bull kelp canopy was reduced by >90% along more than 350 km of coastline. Twenty years of kelp ecosystem surveys reveal the timing and magnitude of events, including mass mortalities of sea stars (2013-), intense ocean warming (2014–2017), and sea urchin barrens (2015-). Multiple stressors led to the unprecedented and long-lasting decline of the kelp forest. Kelp deforestation triggered mass (80%) abalone mortality (2017) resulting in the closure in 2018 of the recreational abalone fishery worth an estimated $44 M and the collapse of the north coast commercial red sea urchin fishery (2015-) worth $3 M. Key questions remain such as the relative roles of ocean warming and sea star disease in the massive purple sea urchin population increase. Science and policy will need to partner to better understand drivers, build climate-resilient fisheries and kelp forest recovery strategies in order to restore essential kelp forest ecosystem services.”
January 30, 2019 – Paper published in Science Advances by Harvell et al – Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides). Quote from lead author: “The main takeaway is the speed with which a multi-host infectious disease can cause decline in the most susceptible host [Sunflower Stars] and that warming temperatures can field bigger impacts of disease outbreaks.” Abstract includes: “Since 2013, a sea star wasting disease has affected >20 sea star species from Mexico to Alaska. The common, predatory sunflower star (Pycnopodia helianthoides), shown to be highly susceptible to sea star wasting disease, has been extirpated across most of its range. Diver surveys conducted in shallow nearshore waters (n = 10,956; 2006–2017) from California to Alaska and deep offshore (55 to 1280 m) trawl surveys from California to Washington (n = 8968; 2004–2016) reveal 80 to 100% declines across a ~3000-km range. Furthermore, timing of peak declines in nearshore waters coincided with anomalously warm sea surface temperatures. The rapid, widespread decline of this pivotal subtidal predator threatens its persistence and may have large ecosystem-level consequences.”
The paper’s discussion includes: “Cascading effects of the P. helianthoides loss are expected across its range and will likely change the shallow water seascape in some locations and threaten biodiversity through the indirect loss of kelp. P. helianthoides was the highest biomass subtidal asteroid across most of its range before the Northeast Pacific SSWD event. Loss or absence of this major predator has already been associated with elevated densities of green (Strongylocentrotus droebachiensis), red (Mesocentrotus franciscanus), and purple urchins (Strongylocentrotuspurpuratus) across their range, even in regions with multiple urchin predators. Associated kelp reductions have been reported following the outbreak . . . SSWD, the anomalously warm water, P. helianthoides declines, and subsequent urchin explosions . . . have been described as the “perfect storm.” This “storm” could result not only in trophic cascades and reduced kelp beds but also in abalone and urchin starvation.”
July 2018 – Research published by Burt et al) quantifies the importance of Sunflower Stars in maintaining kelp forests. Includes that the decline of Sunflower Stars “corresponded to a 311% increase in medium urchins and a 30% decline in kelp densities”. See news coverage on the research at this link.
March 7, 2018 – Additional research by Hewsen et al has found that, while a virus appears associated with the disease in Sunflower Stars, the situation is more complex and the virus does not appear to be the cause in other sea star species. The cause is “likely a complex tango of diverse potential pathogens and environmental conditions” / “We speculate that SSWD may represent a syndrome of heterogeneous etiologies [causes] between geographic locations, between species, or even within a species between locations.” Those considered in the paper in addition to viruses: Drought / excessive rainfall; freshwater toxins (transmitted by excessive rainfall post drought); temperature swings.
This does not let climate change off the hook. Quote by lead author: “Since some of those disease causes may include swings in temperature or precipitation, ultimately which may be related to climate change, we need to focus our efforts on remediating climate change . . ”
The paper suggests renaming the wasting disease to Asteroid Idiopathic Wasting Syndrome because the term correlates with an array of symptoms, “which is more correct for describing this situation, as there are likely multiple diseases present . . .”
Research published in June 2018 (Schiebelhut et al), specifically on Ochre Stars, found that the genetic makeup of the species has changed since the outbreak. Young Ochre Sea Stars are more similar genetically to adults who survived than to those who succumbed. This “may influence the resilience of this keystone species to future outbreaks”. The findings of an additional March 2018 paper (Miner et al) include ” . . . we documented higher recruitment of P. ochraceus [Ochre Stars] 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.
Sunflower star with sea star wasting syndrome. Tissue wastes away. Legs often break off and crawl away briefly before rotting away. Photo – Neil McDaniel; http://www.seastarsofthepacificnorthwest.info
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The content below is from my original blog November 10, 2013:
There has already been much reporting on the gruesome epidemic spreading like wildfire through several species of sea star in the NE Pacific Ocean.
“Sea star wasting syndrome” is incredibly virulent and is causing the mass mortality of some sea star species in British Columbia and beyond. “Sea stars go from “appearing normal” to becoming a pile of white bacteria and scattered skeletal bits is only a matter of a couple of weeks, possibly less than that” (Source #1).
What I have strived to do is bundle the state of knowledge so far, relying heavily on the expertise of two extraordinary divers and marine naturalists: (1) Neil McDaniel, marine zoologist and underwater photographer / videographer who maintains a website on local sea stars and has put together A Field Guide to Sea Stars of the Pacific Northwest, and (2) Andy Lamb, whose books include Marine Life of the Pacific Northwest.
I am hoping that kayakers, beach-walkers and fellow divers will help monitor and report on the spread of the disease but I am also hoping that all of us may learn from this tragedy that has impacted “one of the most iconic animals on the coast of British Columbia . . . more abundant and diverse in our waters than anywhere else in the world” (Source #3).
Sea Star Wasting Syndrome reminds us of the fragility of ocean ecosystems; how very quickly disease could spread in the ocean; and how we are all empowered to reduce stressors that increase the likelihood of pathogens manifesting as disease (e.g. climate change) or even that pathogens enter the environment (e.g. sewage).
Species impacted?
High mortalities (note that the first 4 are members of the same family – the Asteriidae):
Sunflower star (Pycnopodia helianthoides) hardest hit in southern British Columbia. From communication with Neil McDaniel ” . . .so far I estimate it has killed tens, possibly hundreds of thousands of Pycnopodia in British Columbia waters.”
Update January 21st, 2014: Possibly: Rose star (Crossaster papposus) – I have noted symptoms in this species on NE Vancouver Island as has Neil McDaniel in S. British Columbia).
Symptoms and progression of SSWD:
Neil McDaniel shared the following 7 images for the progression of the disease in Sunflower Stars [Source #2 and #14]. See the end of this blog item for images showing symptoms in other sea star species as well as a 1 minute time-lapse clip showing the progression of the syndrome in a Sunflower Star over 7 hours. [Note that the progression of the Syndrome on NE Vancouver Island appears that it may be different from what has been observed further to the south.]
1. In this image most of the Sunflower Stars appear healthy “other than one just right of center frame is exhibiting the syndrome, looking “thinned-out” and emaciated.”
3. This image “shows how the body wall begins to rupture, allowing the gonads and pyloric caeca to spill out.”
As the animals become more stressed, they often drop several rays (which wander off on their own for a while). At this point the body wall becomes compromised and the pyloric caeca and/or gonads may protrude through lesions. As things progress, the animals lose the ability to crawl and may even tumble down steep slopes and end up in pile at the bottom. Soon after they die and begin to rot
5. As things progress, the animals lose the ability to crawl [and hold grip surfaces] and may even tumble down steep slopes and end up in pile at the bottom. Soon after they die and begin to rot.
6. The bacteria Beggiatoa then takes over and consumes all of the organic matter, leaving a scattering of skeletal plates on the bottom. The syndrome develops quickly and in only one to two weeks animals can go from appearing healthy to a white mat of bacteria and skeletal plates
The 1-minute time-lapse video below shows the progression of the Syndrome in a sunflower star over 7 hours.
Cause(s)? To date, the cause(s) have not yet been identified. Scientific opinion appears to be that most likely the cause is one or more viruses or bacteria. As with any pathogen (like the flu virus), the expression of a pathogen as disease is influenced by the number and proximity of individuals and could be exacerbated by environmental stressors.
Using cutting-edge DNA sequencing and metagenomics, Hewson is analyzing the samples for viruses as well as bacteria and other protozoa in order to pinpoint the infectious agent among countless possibilities.
“It’s like the matrix,” Hewson said. “We have to be very careful that we’re not identifying something that’s associated with the disease but not the cause.”
”In previous outbreaks the “proximal cause” was found to a vibrio bacterium but “a recent wasting event on the east coast of the United States has been attributed to a virus . . . such events are often associated with warmer than typical water temperatures . . . Please note that we do not know what is causing Sea Star Wasting Syndrome, and the cause may be different in different regions . . . the period prior to Wasting was characterized by warm water temperatures” (University of California Santa Cruz, Source #4).
Bates et al reported on an outbreak of wasting syndrome in ochre stars in Barkley sound in 2008. This included conducting lab experiments finding that the “prevalence and infection intensity were always higher in warm temperature treatments” and that “small increases in temperature could drive mass mortalities of Pisaster [ochre stars] due to wasting disease.” [Source #13 and #14]
“Do not believe this is related to a warming trend” (Source #18).
“Overpopulation” of sunflower stars appears to be a factor with outbreaks occurring where there is a high abundance of sea stars. “Often when you have a population explosion of any species you end up with a disease outbreak” (Source #5). “This could be perfectly normal as a way to control overpopulation” (Source #18).
“Some initial samples sent to DFO [Department of Fisheries and Oceans] and UBC [University of British Columbia] have not isolated a specific causative agent for this sea star die off. More samples are being collected and additional tests will be conducted” (Source #2 and #7). Viruses are notoriously difficult to detect. Cornell University (New York) has begun viral and bacterial culturing (Source #8). Updates will be provided here as they become available. See Source #14 for the results of pathology reports from October 4, November 12 and November 13.
Quote from Drew Harvell, a Cornell University professor of ecology and evolutionary biology who studies marine diseases: “these kinds of events are sentinels of change. When you get an event like this, I think everybody will say it’s an extreme event and it’s pretty important to figure out what’s going on . . . Not knowing is scary . . . If a similar thing were happening to humans, the Centers for Disease Control and Prevention would commit an army of doctors and scientists to unraveling the mystery.” (Source #12)
Fukushima is a contributing factor?! There is no data to date to support this and, while of course radiation benefits nothing, I worry that pointing the finger away from ourselves takes away from the opportunity to recognize and act on how we all contribute to ocean stressors such as increasing temperature. From Source #19 – “scientists see Fukushima as an unlikely culprit because the die-offs are patchy, popping up in certain places like Seattle and Santa Barbara and not in others, such as coastal Oregon, where wasting has only been reported at one location.”
Ballast water? “From Source #19- “Others have wondered if a pathogen from the other side of the world may have hitched a ride in the ballast water of ocean-going ships. Scientists say this fits with the fact that many of the hot spots have appeared along major shipping routes. However, the starfish in quiet Monterey Bay, Calif. have been hit hard, whereas San Francisco’s starfish are holding strong.”
Has this happened before?
Never to this large a scale. “Although similar sea star wasting events have occurred previously, a mortality event of this magnitude, with such broad geographic reach has never before been documented.” (Source #17).
“Southern California in 1983-1984 and again (on a lesser scale) in 1997-98” (Source #4 and #13)
Florida (Source #5).
Update November 30: Sunflower die offs [on much smaller scale] have been noted in the past in Barkley Sound. In 2008 ochre star die offs were documented in Barkley Sound. In 2009 Bates et. al. reported on this and observed that the prevalence of disease “was highly temperature sensitive and that populations in sheltered bays appeared to sustain chronic, low levels of infection.” (Source #14 and #15).
“Similar events have occurred elsewhere over the last 30 years. Sea stars have perished in alarming numbers in Mexico, California and other localities” (Source #2).
“In July, researchers at the University of Rhode Island reported that sea stars were dying in a similar way from New Jersey to Maine . . a graduate student collected starfish for a research project and then watched as they “appeared to melt” in her tank” (Source #5).
Shellfish Health Report from the Pacific Biological Station (DFO) conducted on 1 morning sun star and 7 sunflower stars collected on October 9, 2013 at Croker Island, Indian Arm; case number 8361.
Bates AE, Hilton BJ, Harley, CDG 2009. Effects of temperature, season and locality on wasting disease in the keystone predatory sea star Pisaster ochraceus. Diseases of Aquatic Organisms Vol. 86:245-251 http://www.ncbi.nlm.nih.gov/pubmed/20066959
Morning sun star with lesions indicating the onset of sea star wasting syndrome. Photo and descriptor – Neil McDaniel; http://www.seastarsofthepacificnorthwest.info Click to enlarge.
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