Five years after a mysterious disease began killing millions of
starfish and turning their tissues to mush, the decimated
population has yet to recover. Meanwhile, researchers continue to
struggle to identify a cause for the disease, which appears to have
uncertain ties to viruses and possibly environmental
conditions.
In Puget Sound, it’s not as easy as it once was to find a
diseased sea star, which seems to be a promising sign until you
consider how many have died. As I learned last week during an
outing to Lofall in North Kitsap, the total number of starfish
remains low compared to four years ago, and recovery has been
minimal, if at all.
Under the Lofall dock,
volunteers have observed that the number of sea stars is still low,
but sick ones are no longer common.
Photo: Christopher Dunagan
Local volunteers have been observing sea stars at Lofall since
the beginning of 2014. I first visited the site the following
summer with three retired women who lead the monitoring effort
there. (See
Water Ways , June 17, 2014.) They are still making regular
trips at low tide, counting and measuring the starfish and looking
for signs of disease.
“The numbers are way down,” noted volunteer Barb Erickson as we
stood beneath the Lofall dock last Friday, “but we haven’t seen
many sick ones. We also aren’t seeing the little ones.”
“Still no babies,” commented Peg Tillery, as we arrived at the
Lofall dock in North Kitsap in search of sea stars clinging to
pilings under the dock.
Barb Erickson examines sea
stars at the base of a pier in Lofall on Hood Canal.
Photo: Christopher Dunagan
“They say there’s a comeback of the little ones,” noted Barb
Erickson, “but I’m not seeing any of them.”
Peg and Barb are two of three retired volunteers who first
brought me to this site two years ago to explain their ongoing
investigation into the mysterious “sea star wasting disease.” Since
our first trip, researchers have identified the virus that attacks
sea stars, causes their arms to fall off and turns their bodies to
a gooey mush.
I first witnessed the devastation in June of 2014, when starfish
were dying by the millions up and down the West Coast (Water
Ways, June 17, 2014). Lofall, a community on Hood Canal, was
just one location where the stars seemed to be barely clinging to
life. Now, just a fraction of the population still survives in many
locations.
Bruce Menge of Oregon State University recently reported an
upsurge in the number of baby starfish on the Oregon Coast,
something not seen since the beginning of the epidemic.
“When we looked at the settlement of the larval sea stars on
rocks in 2014 during the epidemic, it was the same or maybe even a
bit lower than previous years,” said Menge in a
news release from OSU. “But a few months later, the number of
juveniles was off the charts — higher than we’d ever seen — as much
as 300 times normal.”
As Peg and Barb pointed out, the recovery at Lofall has been hit
or miss during more than two years of monitoring the site. I became
hopeful on my return trip to the dock in January of 2015, when I
noticed a mix of healthy adult and juvenile sea stars (Water
Ways, Jan. 20,2015).
This week, the young ones were nowhere in sight. Clusters of
healthy adult ochre stars were piled on top of each other at the
bottom of the piers, waiting for the tide to come back in. I was
not sure what to make of it.
Sea stars clusters on two
adjacent piers at Lofall dock.
Photo: Christopher Dunagan
“it could be worse,” Barb said. “I think it is neutral news.”
Peg agreed, saying, “It could be totally worse.”
Summer has been the period of reckoning in past years, and we
should soon know if we are in for another round of disease, which
could kill off more of the surviving sea stars, or if the disease
is finally on the wane.
Linda Martin, who normally compiles the data, was not along on
this week’s trip to Lofall, but other volunteers filled in for
her.
“It is an interesting ride,” Barb told me, referring to her
experience as a so-called citizen scientist. “It connects you to
the larger picture, and you realize that everything is
connected.”
It is nice for people in the community to know that this
volunteer work is taking place, Barb said, and that someone is
watching for changes in the environment.
“People will come up and ask me if there is anything new, people
who couldn’t have cared less before,” she said.
For those interested in this kind of volunteer work, a good
place to start is Kitsap Beach Naturalists. One can contact Renee
Johnson, program coordinator, at rkjohnson@co.kitsap.wa.us.
Meanwhile, the cause of sea star wasting disease remains
somewhat of a mystery even after its connection to the densovirus,
which is associated with dead sea stars but also has been found in
some that are free of disease.
A laboratory study
led by Morgan Eisenlord of Cornell University found that the
disease progressed faster when adult sea stars were exposed to
higher temperatures and that adult mortality was 18 percent higher
when water temperatures reached 66 degrees F. Temperature was
documented as a likely factor in the spread of disease through the
San Juan Islands.
But temperatures are not the sole controlling factor, because
the spread of the disease has been out of sync with temperature
change in numerous locations.
“The sea temperatures were warmer when the outbreak first
began,” Menge said, “but Oregon wasn’t affected as early as other
parts of the West Coast, and the outbreak reached its peak here
when the sea temperature plummeted and was actually cooler than
normal.”
Could there be another trigger that increases the virulence of
the densovirus?
“Ocean acidification is one possibility, and we’re looking at
that now,” Menge said. “Ultimately, the cause seems likely to be
multi-faceted.”
Starfish that live symbiotically inside a tube sponge were long
believed to assist the sponge with its cleaning activities, while
the starfish received a protective home for being such a helpful
companion. This type of mutually beneficial symbiosis is called
“mutualism.”
But this long-held assumption — that both the brittlestar and
gray tube sponge were benefitting from the deal — turned out to be
wrong when researchers took a close look at the relationship.
The video describing this whole affair and the research behind
it became a finalist in the Ocean 180 Video Challenge, judged by
37,795 students in 1,600 classrooms in 21 countries. Ocean 180 is
all about connecting science to people, and the video challenge is
designed to help scientists turn their discoveries into
stories.
I really like the concept of this contest. Joseph Pawlik, one of
the researchers involved, did a good job telling the story of the
starfish and the sponge in the video production, assisted by Jack
Koch of the University of North Carolina, Wilmington. They called
the video “The maid did it! The surprising case of the
sponge-cleaning brittlestar.”
I won’t give away who killed whom, but answers to the murder
mystery are revealed toward the end of the 3-minute video.
A much more extensive research project involves monitoring the
largest active volcano off the coast of Oregon, a location called
Axial Seamount. University of Washington researchers and students
conducted the research and produced the video about the equipment
used in an extreme environment and how the data are transmitted
back to land via a fiber optic cable.
While the videos of the starfish-and-sponge and offshore volcano
were among the top 10 finalists, neither were among the top award
winners.
You may wish to watch the two first-place videos:
“Drones at the Beach” (amateur category), including University
of Miami and Delft University researchers.
First-place winner Kelly Jaakkola of the Dolphin Research Center
said Ocean 180 is a way to make a connection with the next
generation of ocean scientists:
“For a lot of students, science can have a negative, scary
image. They picture people in white lab coats talking about topics
that nobody understands in the most boring, unimaginative way
possible. If we want to get kids excited about science, we need to
change that image.”
Third-place winner Charles Waters said some of the most
inspiring science writing uses analogies, metaphors and similes to
describe the scientific process and research findings:
“Video helps lift images from print, and the message comes
closer to being an experience for the audience in contrast to a
mere information stream.”
The Ocean 180 Video Challenge is sponsored by Florida Center for
Ocean Sciences Education Excellence.
It was a dark and stormy night — but that didn’t deter the Three
Starfish Musketeers from going out at low tide on Saturday to check
on the condition of sea stars clinging to the Lofall pier.
Researcher Melissa Miner
examines sea stars on the Lofall pier while volunteer Peg Tillery
watches. // Photo by Christopher
Dunagan
If you recall, I introduced these three retired-age ladies in a
story last summer, when they first reported a scene of devastation
on the North Kitsap pier and nearby beach, where a multitude of sea
stars lay sick and dying. Many sea stars were afflicted with a
mysterious disease called sea star wasting disease, which had
already affected hundreds of locations from Alaska to Mexico.
The three women — Barb Erickson, Linda Martin and Peg Tillery —
have been serving as amateur researchers, monitoring the Lofall
beach, like hundreds of other volunteers at various locations along
the West Coast. When they started monitoring the beach in February
2014, they observed dozens of healthy sea stars — but conditions
changed dramatically by June.
Barb tells the story with photographs in her blog,
Ladybug’s Lair, and I’ve included a summary of her observations
at the bottom of this page.
I was not sure what to expect when I accompanied the three women
to the Lofall pier on Saturday, the night before the Seahawks NFC
championship game. Joining us on this dark, rainy night were
researcher Melissa Miner of the University of California at Santa
Cruz, who has been working with volunteers up and down the coast.
Also with us was Jeff Adams of Washington Sea Grant, who has been
coordinating local efforts.
What we saw Saturday was a great many more young sea stars than
last year, along with adults that seemed to be healthy. None of the
starfish showed signs of disease.
“That’s good news, and there are some big ones in here,” Melissa
commented, as she examined the pilings where the monitoring is
taking place.
“It feels better this time when we’re out here,” Jeff said,
adding that last fall he saw far more sea stars turning to mush and
disintegrating. “All we saw were body parts strewn all over.”
Melissa said researchers are seeing much greater numbers of
juveniles at many of the sites along the coast and inner waterways.
That could mean that the population is rebounding, but there is
still great uncertainty, she said. Some evidence points to
temperature as playing a role in the disease.
“It seems like around here temperature is a pretty big factor,”
she said. “When summer comes around, we’ll be able to see how
things change.”
In November, a group of scientists identified a virus, known as
densovirus,
that is clearly associated with diseased sea stars. Further work is
needed to determine how the virus affects the animals and what
other factors are in play. See
Proceedings of the National Academy of Sciences and my Nov. 22
blog post in
Water Ways.
If we are indeed in a period of recovery at Lofall — and
hopefully many other sites — it will be interesting to see how the
ecosystem rebounds and how long it takes for the sea star
population to return.
Jeff Adams told me in November that he hopes to maintain the
volunteer monitoring program for years to come — not just to track
the sea star disease but to understand more about the cycles of
marine life.
Barb Erickson summarized the findings of the group before
Saturday’s outing:
“For our data collection, all of our observations take place in
a specific area centered on three concrete piers under a dock at
Lofall. In the beginning, a great number of ochre/purple sea stars
and a few mottled stars congregated on each of the piers. That
number has steadily declined over the past year and, although we
are aware that these animals come and go with the tides, we feel
their decline is directly related to the disease.
“We began our observations in February 2014, when we counted 56
sea stars, adults and juveniles. Many small juveniles were tucked
away in corners and under cables on the piers. Of those 56, only 4
appeared to be in the early stages of disease. In April we counted
100, all of which appeared healthy. In May, of the 53 we found, 33
were in various stages of illness. By June, the majority of the sea
stars were dead or dying. Of the 12 living stars we found, 11 were
in the early stages of disease.
“Throughout the rest of the summer and early Fall, the area was
littered with dead stars and the number of living ones, including
juveniles, continued to decrease. By October, we found a total of
only 7 living adult stars and no juveniles; 5 were diseased. In
January 2015, we found 56 (20 adults and 36 juveniles); all
appeared healthy.”
The count from Saturday’s outing was 48 sea stars (21 adults and
27 juveniles), and all appeared healthy.
I’ll never forget my visit this past summer to the Lofall dock
and nearby beach on Hood Canal in North Kitsap. It was a scene of
devastation, in which starfish of all sizes were losing their limbs
and decomposing into gooey masses.
Barb Erickson and Linda Martin
examine young sea stars for wasting disease at Lofall pier last
summer.
Kitsap Sun photo by Meegan M. Reid.
My guides on the excursion were three women who had been
watching for changes in sea stars as part of a volunteer monitoring
program being conducted up and down the West Coast. The three were
shocked at what they saw on the trip, as I described in a story for
the
Kitsap Sun as well as in a blog post in
Water Ways.
Now, researchers are reporting that a virus, known as
densovirus, appears to be playing a central role in the devastation
of millions of sea stars from Alaska to Mexico. Their findings were
reported in the
Proceedings of the National Academy of Sciences (PDF 1.1
mb).
Many questions remain about the mysterious affliction known as
“sea star wasting syndrome.” For one, why were the sea stars
affected over such a wide area, all at about the same time?
As described in the report, the researchers went to museums with
sea stars preserved in alcohol and found that the virus was present
in specimens collected as long ago as 1942 at various West Coast
sites. Minor outbreaks of the wasting syndrome have been reported
through the years, but obviously something much bigger is taking
place now.
Sea star near
Lofall
A change in the environment, such as ocean acidification, has
been suggested as one possibility. A change in the virus, such as
we see for the flu virus in humans, is another idea. It could also
be related to an over-population among the sea stars
themselves.
Jeff Adams of Washington Sea Grant, who is leading the local
monitoring program in Kitsap County, said it is good that
researchers have found something to go on, but other causative
factors are yet to be discovered.
“Why and where; those are two of the things still on the table,”
Jeff told me. “What are the environmental factors that drove this
much larger die-off? Was it something that made the virus more
prevalent or something that made the sea stars weaker?”
Jeff noted that the cause of death may not be the virus itself
but rather opportunistic pathogens that attack the sea stars after
their immune systems are weakened by the virus.
“Density may have played a factor,” he said. “Sea star
populations have been thick and strong over the past 12 years. When
you get a lot of individuals in close proximity, you can get sudden
changes. Marine populations fluctuate quite a bit naturally.”
Jeff hopes to maintain the volunteer monitoring program for
years to come, not just to track the disease but to understand more
about the cycles of marine life. Of course, he would like to be
able to report on an ongoing recovery of sea star populations from
their current state of devastation. Will the recovery occur in
patches or uniformly at all monitored sites?
“Ideally, this will run its course, and we will start seeing
juveniles showing up over the course of the summer,” he said. “How
many of them will disappear?
“Ideally, we will be able to maintain some sites for much
longer. For me, as a naturalist, there are lots of questions about
natural historical cycles that have not been addressed. A lot of
critters are facing challenges (to their survival).”
In Puget Sound, these challenges range from loss of habitat to
pollution to climate change, and the predator-prey balance will
determine whether any population —and ultimately entire species —
can survive.
Linda Martin, one of the volunteers who gave me a tour of the
Lofall beach, said she was glad that researchers have identified a
viral cause of the sea-star devastation, but it remains unclear how
that is going to help the population recover.
Because of the timing of low tide, the three women have not been
to Lofall since early October, when the population was “completely
depleted,” according to Linda. But they are planning to go back
next weekend.
“We are anxious to go out and see if there is anything there,”
she said. “We have not seen any juveniles for a long time.
Originally, when we started out, we were seeing uncountable numbers
of juveniles.”
As for the new findings, I thought it was interesting how the
researchers removed tissues from diseased sea stars then filtered
out everything down to the size of viruses. After that, they
exposed one group of healthy sea stars to a raw sample of the fluid
and another group to a heat-treated sample. The raw sample caused
disease, but the heat-treated sample did not.
They then used DNA techniques to identify the virus, which was
found in larger and larger concentrations as the disease
progressed. Check out the research report in the
Proceedings of the NAS (PDF 1.1 mb).
Jeff Barnard of the
Associated Press interviewed researchers involved in the study
and others familiar with the problem.
I went to the beach last week to see some starfish with three
trained volunteers. What we found was a scene of devastation on the
pier and along the beach at Lofall, located on Hood Canal in North
Kitsap.
Barb Erickson photographs a
sea star afflicted with sea star wasting syndrome. Another infected
star dangles by one arm.
Photo by Meegan M. Reid
What had been a large population of sea stars, as scientists
call them, were now generally missing. Those that remained were
mostly dead or dying. Healthy ones were in a minority.
Sea star wasting syndrome is now clearly present on our local
beaches, just as it has affected hundreds of locations from Alaska
to Mexico.
On Friday, I was fortunate to be in the company of three women
who knew quite a bit about sea stars. They were careful in their
observations and precise in their measurements, able to provide
data to a network of observers measuring the progress of this
disease along the West Coast.
But these three women — Barb Erickson, Linda Martin and Peg
Tillery — also expressed their feelings of loss for the sea stars,
a creature considered a key part of a healthy marine ecosystem.
As I reported in my story, published
Sunday in the Kitsap Sun, Barb was the first to assess the
situation as we arrived at the beach, comparing her observations to
just two weeks before.
“‘Oh my!’ shouted Erickson as she reached the base of the pier
and took a look at the pilings. ‘I can see right now that there are
hardly any (sea stars) here. These corners were just covered the
last time. Now these guys are just about wiped out.’”
“’Look at the baby,’ lamented Tillery, pointing to a tiny sea
star. ‘He has only four arms, and he’s doing that curling-up thing
… We had so much hope for the babies.’”
Melissa Miner, who is part of a coastwide monitoring program,
told me that researchers are working hard to find a cause of the
advancing affliction. But so far no consistent pattern has emerged
to explain every outbreak.
A leading hypothesis is that something is causing the sea stars
to be stressed, weakening their defenses against the bacteria that
eventually kill them. The stressor could be temperature, she said,
or possibly other factors such as increased acidity or low-oxygen
conditions. Perhaps another organism attacks the immune system,
leaving the sea stars vulnerable to an opportunistic bacteria.
Researchers may find multiple pathways to the same conclusion: a
dramatic decline in the sea star population, both at the local
level and throughout their range along West Coast.
When I hear about a population crash, I think about the basic
tenets of population dynamics. Is it possible that the sea star
population has reached an unsustainable level, given the available
food supply and other factors, and that widespread disease is a
natural outcome? Will the decline of sea stars be followed by an
overpopulation of mussels or other prey, leading to a decline in
ecosystem diversity? How long will it take for the sea stars to
recover? These are issues worthy of study in the coming years.
But I’m haunted by another prospect. Having seen our familiar
starfish attacked by strange bacteria and turned to mush, what lies
in store for other marine organisms? Could ecological stress and
other mysterious pathogens lead to the devastating loss of other
marine species? Who will be next?
Peg Tillery, Linda Martin
and Barb Erickson take notes on sea stars clinging to the Lofall
pier.
Photo by Meegan M. Reid
