Pacific Rocky Intertidal Monitoring: Trends and Synthesis
Sea Star Wasting Syndrome Updates
Please continue to submit observations after spending time diving or tidepooling. 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.
In addition, we are considering the development of a mobile app that will provide educational information about sea stars and the wasting disease, as well as ID guides and survey protocols. This mobile app will be designed for Android and IOS platforms. We would greatly appreciate your input on the utility of this app and have put together a brief survey to gauge potential users’ interest. The survey can be found here.
|Jul 29, 2014
||Jan 21, 2014
||Nov 8, 2013
||Oct 24, 2013|
UCSC intertidal researchers have continued to monitor sea star populations along the US west coast this spring and summer. From Washington down through central California most populations of ochre stars in the intertidal are currently showing low prevalence of disease (under 10% of population diseased, aside from one site at Cape Arago, OR at 13%). However, most of these sites show significant decreases in population size compared with the long term mean prior to this SSWS event, indicating a high impact overall. The handful of sites that do not show population declines have significantly fewer adults compared to past data, but have had an influx of juveniles which account for the seemingly “normal” population numbers. Sites showing healthy populations of juveniles include Fogarty Creek in Oregon, False Klamath Cove in Redwood National and State Parks, and Bodega Bay in Northern California. Most of these juveniles appear healthy, and will be reevaluated during fall sampling.
Monitoring sites just north of Point Conception, at the southern end of central CA, tend to show higher prevalence of symptoms, though lower numbers of sea stars overall are likely the reason for this “higher” prevalence. One diseased star out of four observed yields a higher prevalence ratio (25% at Shell Beach) than sites where sea stars are more abundant (such as 16 out of 183, or 9% at Enderts Beach). The four Orange County monitoring sites in southern California turned up a total of four ochre stars, with two of the sites having zero ochre stars remaining in the monitoring plots. No symptoms were observed in these four stars, though past total abundance for these sites would have averaged over 150 sea stars, making the effects of this SSWS event apparent.
In the Salish Sea/Puget Sound region of Washington, disease prevalence was low within plots at long-term monitoring sites when they were sampled in June (but note that population sizes were down substantially from previous years), but more recent observations from citizen scientists indicate that the disease is re-emerging in some areas. A few sites with high numbers of juvenile ochre stars and mottled stars in winter 2014/spring 2015 have shown significant declines. Very little is known about “normal” mortality rates in this smallest size class of sea stars, so it is possible that loss was due to predation (gulls were observed eating small stars), movement of individuals (e.g. to the subtidal), or they could have succumbed to SSWS.
Sea stars with symptoms of wasting syndrome continue to be observed along the west coast of North America, and remain geographically patchy. Some sites monitored by citizen scientists in Washington, which had previously shown disease symptoms for many months, have recently been reported to have only healthy individuals, and in a few areas, substantial numbers of juveniles have been recorded. However, the opposite is true for other sites in Washington. Two of the long-term monitoring sites where SSWS was first observed in low levels in June 2013 (Starfish Point and Sokol Point), had disease prevalence ramp up in November 2014 to as high as 60%. While some sites were immediately highly impacted by the syndrome, these sites were not greatly impacted until nearly 1 1/2 years after the first symptoms were seen. As for the sites that are currently free of diseased stars, continued sampling will determine whether these sites are indeed beginning to recover, or whether they are merely experiencing a pause in the progression of SSWS.
The current status of SSWS is unknown for many MARINe monitoring sites because bi-annual sampling for most sites occurs in spring and fall. Beginning this month, many sites along the coast will be resampled and we will be able to assess the condition of sea star populations in those areas. Several sites sampled in December 2014 in Redwood National and State Parks showed relatively low rates of infection, 6% to 20%; however, ochre star abundances at these monitoring sites had dropped well below the long-term average, likely due to the impact of SSWS. Qualitative observations also continue to be reported from locations along the coast where sea stars are conspicuously absent from places people have observed them historically. While not quantitative, these observations provide important insight to the overall picture of the impact of SSWS.
As noted in the previous update, disease has also been seen in urchins in some locations along the coast. It is still unknown whether this is related to sea star wasting syndrome. Warmer than usual water temperatures may be playing a role, as has been the case in past events. In the last few months urchin disease symptoms have been reported in southern California and Baja California. MARINe researchers are currently developing protocols for monitoring urchins. These protocols were discussed recently at the MARINe consortium’s annual meeting, along with information sharing and regional updates about the progression of SSWS along the entire west coast.
The northern-most observation of SSWS in the field is now Sawmill Bay, east of Anchorage, Alaska. While it was hoped that Alaska’s colder waters might provide reservoir populations of healthy sea stars, increased observations of disease in Alaska have made this unlikely. Affected mottled stars were seen this fall in Jakalof Bay, just west of Kenai Fjords National Park, as well as more observations of diseased stars around Juneau and Sitka, Alaska. Along the rest of the west coast, observations of disease continue throughout, but with varying levels of impact to sea star numbers.
In Central California fall long-term monitoring surveys are currently in progress, but for those sites sampled, 9 of 16 (56%) showed declines in Pisaster ochraceus numbers due to SSWS. Sites experiencing “lower” impact have all lost large numbers of adult stars, but higher population numbers are present due to a large influx of recruits, or healthy baby sea stars. While diseased juvenile sea stars have been observed, the majority appear healthy thus far. Only time will tell whether these juveniles live to replenish populations, or become diseased themselves. Please keep your eyes open for juvenile sea stars and report them on our juvenile observation log.
Another development since the last update is the recent observation in Southern California of wasting in other echinoderms, such as sea urchins. Urchin die-offs have occurred in the past during warm-water events, often associated with sea star wasting. It is unknown whether the current observations of urchin disease and die-offs are connected to SSWS, or are the result of another pathogen, potentially connected to the abnormally warm water temperatures that have been present in southern California. We encourage citizen observers as well as other researchers to monitor the condition of urchins and other echinoderms in addition to sea stars. Our updated disease observation log now includes a space to report observations of urchin disease.
The recently published paper by Hewson et al. “Densovirus associated with sea-star wasting disease and mass mortality” provides evidence for a link between a densovirus (SSaDV) and sea star wasting syndrome (SSWS). This is an important piece of the SSWS puzzle, but we want to stress that there is still much work to be done before this mysterious disease is fully understood. Importantly, Hewson’s testing of sea star tissue collected from as far back as 1942 indicates that the SSaDV has been around for a long time, yet has never resulted in mass mortality on the geographic or temporal scale we are currently witnessing. Thus, while a culprit may have been identified, we still don’t fully understand the cause. The complete story is likely a complex interaction of multiple factors, and may involve different factors in different regions. For example, the emergence of SSWS in some areas appears to be correlated with increased water temperature, but this does not apply generally across the entire west coast. Finally, the discovery that the SSaDV is present in other echinoderms, such as urchins, which are not currently experiencing mass mortality, suggests that these species could serve as “reservoirs” for the virus that could continue to infect sea stars for many years to come. It may also be only a matter of time before we see broad-scale mortality of other echinoderm species, including urchins and sea cucumbers.
Sea Star Wasting Syndrome (SSWS) continues to be observed along the West Coast of North America. The known current geographical range has not expanded much since the last update, though unfortunately some gaps within the range have now filled in as also being affected. The Anchorage Museum continues to be the most northern known location at which SSWS has been observed, though the most recent northern observation in the field was Peterson Bay, Alaska, southwest of Anchorage, in late July of this year. The current most southern known location for this event of SSWS was on North Coronado Island, in northern Baja California from early April this year.
Unfortunately, this past spring, sea star populations began crashing in some areas where disease presence had previously been minimal or absent, and high rates of disease were documented among the remaining individuals. The most noteworthy region was the Oregon coastline. At rocky intertidal sites along the Oregon coast in late April 2014, the percent of diseased ochre stars (Pisaster ochraceus) was less than 1% of those surveyed and abundances of ochre stars were within normal ranges, based on long-term monitoring. By late June 2014, those same sites had significantly lower abundances of ochre stars, and of those remaining, the percent showing disease ranged from 18-64%. It is unknown why that stretch of coast was not impacted until much later than most of the rest of the affected range.
During long-term monitoring of MARINe sites done in fall 2013, 39% of sites surveyed by the UCSC team in central and northern CA showed high levels of wasting. By summer 2014, 87% of sites sampled in spring and summer had high levels of wasting. One encouraging finding was the presence of many juvenile sea stars at some sites where ochre star populations have been devastated by SSWS. During spring 2014 surveys of long-term rocky intertidal sea star plots, several sites in the Monterey Bay region had numbers of juvenile sea stars higher than ever recorded during the monitoring period (generally around 15 years). Almost universally, there has been a decline in abundance of large ochre stars; some of these sites had numbers of juveniles far above average, while others had only average or no recruitment. Long-term monitoring surveys this fall will allow us to see whether the juvenile sea stars seen this past spring have survived, and whether the influx of juveniles has extended to additional sites.
Only time will tell whether these juveniles will grow to replenish the populations at some sites, or whether they too will become afflicted with the disease. Our monitoring continues to track the occurrence of SSWS along the coast and we encourage other researchers as well as the public to continue to submit observations to our database via our website. We are, however, beginning a new phase of monitoring, focusing on 1) the possible ecological consequences this disease may have on the communities in which sea stars live and 2) the potential for recovery of sea star populations, particularly in areas where we are seeing an influx of juvenile stars. For more information and to submit observations of juveniles, please see our page on Ecological Consequences of SSWS.
Over the past year, much of our effort has focused on documenting the progression of sea star wasting syndrome (SSWS) along the West Coast of North America and across a range of sea star species. That effort continues, however, we are now moving into a new phase in the assessment of sea star wasting: the ecological consequences from the loss of these species. For more information, please visit this page.
While the geographical range for which we have received reports of sea star wasting syndrome has expanded little since the last update (the southernmost observation is now San Diego County rather than Orange County, CA), we continue to fill in gaps in spatial coverage. Observations are coming from MARINe Long-Term Monitoring and citizen science groups such as LiMPETS (Long-Term Monitoring Program and Experiential Training for Students), colleagues at a number of universities and government agencies, as well as the general public. In addition, sea star assessment surveys are now being done by a team from UC Santa Cruz, with their entire focus being the assessment of sea star condition in areas with less frequent monitoring.
In Washington, rapid funding from WA Sea Grant and National Science Foundation (NSF) is being used to survey intertidal and near-shore areas of the coastline where we have little to no information about sea star populations. Recently surveyed areas include: 1) the north coast of the Olympic Peninsula, from Salt Creek to Port Townsend, 2) Whidbey Island, and 3) the mainland coast near Bellingham. Additional surveys are being done in the San Juan Islands by researchers at Friday Harbor Labs. Rapid funding is also being used to train citizen science groups to implement sea star monitoring protocols. Thus far, citizen science monitoring sites have been established on Bainbridge Island and at Edmonds Underwater Park, with many more in the works. Results from recent surveys show that wasting syndrome has heavily impacted several species of sea stars at sites in the Puget Sound region, but the impact appears to be much lower farther to the north (along the northeast coast of Whidbey Island, in the San Juan Islands, and around Bellingham), and to the west along the Strait of Juan de Fuca.
In Oregon, wasting syndrome in sea stars has been observed at two sites. However, the populations have remained stable and the percent affected has been very low. The UC Santa Cruz survey team will visit several of our long-term monitoring sites at the end of January to help fill in some of the gaps in our knowledge about the presence of wasting along the OR coast.
Researchers at UC Santa Cruz have recently visited the northern coast of California and observed diseased individuals at 7 of 8 sites between Crescent City and Bodega Bay, though the percent affected was low at these sites. Reports from others in this region include sites with only apparently healthy individuals, so symptoms of wasting syndrome continue to be patchy, though widespread.
UC Santa Cruz is teaming up with divers from the Monterey Bay National Marine Sanctuary to re-survey PISCO (Partnership for Interdisciplinary Studies of Coastal Oceans) subtidal sites from Santa Cruz to Santa Barbara with historic sea star data. Wherever possible, these will be paired with our intertidal monitoring sites, which will allow for a more complete understanding of the impacts of wasting syndrome. Evidence from the few areas where we have both intertidal and subtidal survey data suggest that the effects of wasting syndrome may be more severe subtidally vs. intertidally.
These subtidal surveys are urgently needed because we are receiving numerous, new reports from the mainland Santa Barbara area about wasting sea stars. Thus far, the Channel Islands appear largely unaffected by wasting syndrome. A few ochre stars showing signs of the disease were found on San Clemente and Santa Rosa Islands, but no sick individuals have been reported from San Nicolas, Santa Cruz, Santa Barbara, Anacapa, or Catalina Islands. ROV surveys around oil platforms south of Santa Barbara also did not turn up diseased sea stars. However, a collection of apparently healthy sea stars from Catalina Island were brought to the California Science Center, and within a few days many were showing signs of wasting. Veterinarians at the center are currently experimenting with various treatments, which may aid in determining the cause of this wasting event.
One potentially positive finding has been an apparent increase in the observation of sea stars re-growing lost arms. While arm-regrowth is not unusual in sea stars, the number of individuals recently observed with new arm “buds” has been higher than typically noted in some areas. In addition, we have noticed sea stars with what appear to be “scars” from healed lesions. Both of these observations suggest that sea stars can potentially recover from the effects of wasting syndrome.
The cause of the wasting event is still unknown. Researchers from universities including Cornell, University of Rhode Island, Brown, and Roger Williams continue to work to determine whether the root cause of the disease can be attributed to a pathogen, and many groups are looking for patterns in the geographic extent and spread of wasting syndrome, which might suggest certain environmental factors as possible causes. There has been substantial speculation in the media that the disease could be a result of increased radiation from the nuclear power plant disaster in Fukushima, Japan. We have no evidence to suggest that radiation is a likely culprit.
We continue to receive many reports of sea star wasting along the West Coast of the United States. To date, our most northern report comes from the Anchorage Museum in Alaska. There, mottled sea stars (Evasterias spp.) in the aquarium showed signs of wasting. These individuals were collected from Whittier, AK and Seward, AK, though it is unknown at what point they became sick.
During the last couple weeks, the UC Santa Cruz group sampled a number of our Long-Term Monitoring sites in central California. Most sites had at least a few affected individuals of the ochre star (Pisaster ochraceus). We were able to confirm presence of wasting in San Luis Obispo County, though diseased individuals were less prevalent overall than what we have observed in the Santa Cruz County area. Intertidal Long-Term Monitoring plots at Hopkins Marine Station were recently sampled with only approximately 2 ½ weeks in between surveys. When sampled on October 18, there were no signs of disease, and the abundances in the plots were within fluctuations documented since we established monitoring plots in 1999. We resampled the plots on Nov 5 and observed disease in about half of the ochre stars (Pisaster ochraceus). Overall abundance had dropped quite a bit, lower than recorded anytime during the previous 14 years of monitoring. We also received reports that in the subtidal off Hopkins Marine Station, sunflower stars (Pycnopodia helianthoides) had been abundant several weeks ago, but during a recent class dive trip, none were observed (Raimondi pers. com.). Observations such as these emphasize how quickly sea stars can go from appearing healthy to dying from whatever is causing this wasting event.
Currently, our most southern report along the West Coast comes from Laguna Beach in Orange County, CA. Based on our collected observations to date, it seems that while wasting syndrome is present in southern California, the percent of affected individuals is much lower than what has been documented farther north.
The cause of the wasting event is still unknown. Researchers from universities including Cornell, University of Rhode Island, Brown, and Roger Williams continue to work to determine the pathogen.
Signs of sea star wasting disease have been popping up on both the East and West Coasts of the United States, as well as reports globally. On the West Coast, sea star wasting has been observed as far north as Southeast Alaska, and as far south as Orange County, California. To date, we have received reports of at least 10 species of sea stars showing signs of infection. Reports of sea star disease and mortality on the East Coast began showing up in articles during July of this year. On the West Coast, sea star wasting was first documented in June (although see Bates et al. for 2008 event), and by September observations were much more widespread, with accounts of diseased, dying and dead sea stars from numerous locations along the West Coast.
The first evidence of a possible wasting event came in June when Long-Term Monitoring sites in Washington (monitored by Olympic National Park) recorded diseased stars with percent affected rates between 3-26%. Symptoms of wasting disease in a few Pisaster ochraceus were also noted in August at an intertidal Biodiversity site in Southeast Alaska. Articles from British Columbia, Canada report sightings of dozens of dead sea stars (notably Pycnopodia helianthoides) beginning in September, not far from Vancouver. One report from Vashon Island in Puget Sound indicates signs of wasting in Pycnopodia helianthoides from March of this year. This is the earliest account we have on the West Coast for 2013. From Friday Harbor Laboratories, we have received a report of diseased Henricia spp. and Evasterias troschelii at the southern tip of San Juan Island. In Oregon, we saw no obvious signs of wasting sea stars during Long-Term Monitoring surveys in May-August. Word-of-mouth accounts indicate that there may be wasting occurring at some sites in Oregon, and we hope to have more information from that section of coast soon.
In California, accounts of wasting in sea stars range from just north of Bodega Bay down to Orange County. In the Bodega Bay area there have been reports of wasting in sea stars both subtidally and intertidally. Researchers from UC Davis Bodega Marine Laboratory have observed wasting in Pisaster ochraceus in the intertidal at Schoolhouse Rock, just north of Bodega Bay, since spring 2013. In San Francisco, at the Gulf of the Farallones National Marine Sanctuary office building, Pisaster ochraceus in the office aquarium began “falling apart” in early October. Numerous observations of wasting in sea stars have recently been made in the region between San Francisco south to Big Sur. Accounts have come by way of Long-Term Monitoring from MARINe, LiMPETS, and PISCO, and from researchers from multiple institutions such as Long Marine Lab, Monterey Bay Aquarium Research Institute (MBARI), Monterey Bay Aquarium, and Moss Landing Marine Laboratories, as well as from recreational divers. In central California, species affected thus far include Pisaster ochraceus, Pisaster brevispinus, Pisaster giganteus, Dermasterias imbricata, Asterina (Patiria) miniata, Orthasterias koehleri, Pycnopodia helianthoides, and Henricia spp.
Interestingly, observations of wasting are patchy. For example, wasting sea stars have been seen subtidally off of Hopkins Marine Station in Monterey, but extensive searching in the intertidal nearby turned up only healthy looking individuals and abundances are within the natural fluctuation observed in Long-Term Monitoring plots at that site. Multiple other sites, however, have shown drastic declines in abundance below the fluctuation typically observed at those sites. In San Luis Obispo County, reports of wasting come from Corallina Cove in Montaña de Oro State Park. There, a CA State Parks scientist received information that sea stars were washing up on the beach; it has not yet been confirmed that this could be attributed to wasting.
The cause of this wasting event is still unknown, though researchers from various universities including Cornell, University of Rhode Island, Brown, and Roger Williams are currently working to identify the pathogen.
For more information about Sea Star Wasting Disease, please see visit our Articles, Publications, and News Broadcasts page.