Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • BCO-DMO Processing Description
• Data Files
• Supplemental Files
• Related Publications
• Parameters
• Project Information
• Program Information
• Funding

This time series was funded in conjunction with the Long Term Research in Environmental Biology [LTREB] program including the LTREB project listed on this page (Award DEB-2050017) and prior awards (Award DEB-1050694,DEB-1554702).

Organism identifiers (Life Science Identifiers, LSIDs):
Mytilus californianus, urn:lsid:marinespecies.org:taxname:367837
Pisaster ochraceus, urn:lsid:marinespecies.org:taxname:240755
Pisaster, urn:lsid:marinespecies.org:taxname:240754

As detailed previously (Menge et al. 2004, 2016, 2023), we quantified field predation rates by determining loss rate of transplanted mussels exposed to sea stars compared to mussels protected from sea stars. Replicated experiments were conducted at all sites except Tokatee Klootchman, and each year 2007-2023, except for Rocky Point which began in 2016. In March-April each year, we translocated 10 clumps of 30-50 mussels ranging in shell length from 3-5 cm (easily eaten by adult Pisaster) to plots within the foraging range of Pisaster near the mid-low zone transition, just below the existing mussel beds. After 4-6 weeks of allowing them to reattach under plastic mesh, we removed the plastic mesh. We then fastened wire mesh open-topped 4-sided cages around 5 plots to prevent predation by Pisaster and fastened 2-sided partial cages next to 5 plots to allow predation, with spatially paired replicates of each treatment. We monitored the number of surviving mussels every 2-4 weeks from ~June-December of each year, thus encompassing the period of most active predation. To calculate predation rates, after adjusting for background mortality in exclusion cages, we regressed the number of mussels over time in each plot and used the slope as an estimate of predation rate (in +Pisaster treatments) or background mortality (in -Pisaster treatments). We excluded time points after the first zero (i.e., when all mussels had been eaten), when mussels increased by more than 3 (these are counting errors), or when the number of mussels dropped by more than 5 while the plot was either buried in sand, a cage was missing, or a sea star invaded the cage.

* sheet 1 within the submitted file "BCODMO_PredRateMaster_1990-2023_2024-09-11_SAG.xlsx" (file version uploaded 2026-05-07) was imported into the BCO-DMO data system for this dataset. Values "NA" imported as missing data values. Table will appear as Data File: 990987_v1_predation-rates.csv (along with other download format options).

Missing Data Identifiers:
* In the BCO-DMO data system missing data identifiers are displayed according to the format of data you access. For example, in csv files it will be blank (null) values. In Matlab .mat files it will be NaN values. When viewing data online at BCO-DMO, the missing value will be shown as blank (null) values.

* Column names in the supplemental table were adjusted to conform to BCO-DMO naming conventions designed to support broad re-use by a variety of research tools and scripting languages. [Only numbers, letters, and underscores. Can not start with a number]

* Dates converted to ISO 8601 format

Supplemental files:

* Site list exported from supplied SiteList_STARS.xlsx(version from 2026-05-11) Sheet1 after changing date format to ISO 8601. Attached to dataset as sitelist_stars.csv. Sheet2 contained column information which was added to the sitelist_stars.csv file description after modifications to match the data table (description for column "state" added, column name "LoggerCode_OSU" is "OldLoggerCode_OSU" in data table).

* Validation Lists extracted from sheet ValidationList in BCODMO_BTMasterAnnot_2000-2024_2025-03-06_SAG.xlsx. Reformatted to not imply this is a table but rather unique lists of controlled vocabulary elements the study used.

This study will investigate the ecological consequences of the decimation of sea star populations by wasting disease along the Oregon coast. Hallmarks of wasting disease are the formation of sores on the sea star that progress to cause loss of arms, and ultimately death of the animal. Wasting disease was reported in sea star populations including those of the purple sea star, Pisaster ochraceus, in British Columbia, Washington, and California as early as April 2013. In Oregon, wasting was first observed in April 2014, and by June 2014 rates of infection ranged up to 80%, and sea star abundance had declined. At that rate, many populations may disappear by the end of summer 2014. Prior research has shown that in the absence of the purple sea star, mid-shore mussel populations increase, and ultimately overgrow the sea weeds and invertebrates that occur low on the shore, reducing biodiversity. However, because disease events of this magnitude have never occurred along the entire coastline, it is unclear if the small-scale expansion of mussels observed previously will be a general result of this event. One possibility is that predators unaffected by wasting, such as whelks and crabs, will increase their predation effects and blunt the expected invasion of mussels to the low shore. The research in this project will evaluate this possibility by testing the role of these alternative predators. Broader Impacts include the training of undergraduate and graduate students, the involvement of coastal residents and the production of microdocumentaries and video to document the changing context of this ecosystem.

The research project is designed to test three hypotheses. First, that in the absence of Pisaster ochraceus, predation by whelks will increase in strength through increases in whelk abundance and in whelk size, and at least partially compensate for the absence of Pisaster. Second, the small sea star Leptasterias spp. will also expand its role as a predator through increased size and abundance, and expansion of its habitat beyond mussel beds. Although individuals of this sea star have been observed to suffer from wasting as well, the frequency so far appears low, and it seems likely this species may persist. Third, the crab Cancer productus, normally mostly a subtidal species, will expand its range into the intertidal and help to compensate for the loss of Pisaster. Tests of these hypotheses will include manual removal experiments (whelk removal, Leptasterias removal, removal of both and of neither), cage exclusion experiments (whelk exclusions), cage inclusion-exclusion experiments (Leptasterias inclusion, Leptasterias exclusion). Experiments will be replicated with appropriate controls, and done at multiple sites on the central Oregon coast that vary naturally in population abundances, rates of prey and predator recruitment, and oceanographic conditions. Results obtained under this unprecedented set of circumstances will deepen and expand our empirical understanding of the dynamics of an iconic ecosystem, and will help parameterize community models.

Additional Project Information: Sea Star Wasting Map

This project is affiliated with the Partnership for Interdisciplinary Studies of Coastal Oceans (PISCO) and Multi-Agency Rocky Intertidal Network (MARINe).

NSF abstract:

Diseases that compromise the health of predators can lead to large, abrupt and sometimes unexpected changes in the structure of ecosystems. This project will combine field surveys, manipulative experiments and mathematical models to both understand and predict the ecosystem-level effects of the unprecedented sea star wasting disease (SSWD) outbreak that devastated populations of Pisaster ochraceus, a critical predator, across the West Coast of the United States. Specifically, the project will determine (1) the ecological and environmental factors that promote vs. compromise the resilience of intertidal ecosystems to sea star wasting disease, (2) document the pace and extent of recovery from this major disturbance across the West Coast of the United States, and (3) identify hotspots of resilience to sea star wasting disease that may serve as important conservation targets to preserve these iconic ecosystems. The research will address important societal needs by cross-training undergraduate and graduate students in disease ecology, marine biology, mathematical modeling and biostatistics. Students from underrepresented groups will be recruited broadly from West Coast states. Each summer, four undergraduate students will be trained in rocky intertidal field research techniques. SSWD-focused modules will be developed and used in ecology courses at each institution to emphasize the importance of quantitative and interdisciplinary training for addressing important questions in biology. Graduate students will work with the Oregon Migrant Leadership Institute (OMLI) for migrant workers and their children to create workshops for students about SSWD. The PIs will continue interacting with the media and public groups, and will expand outreach activities through The Nature Conservancy and CoastWatch-sponsored workshops for high school teachers interested in involving students in sea star monitoring to ensure that the results of this project are disseminated beyond traditional academic circles. Finally, a series of model-based interactive web modules will be created as part of this project to illustrate the ecosystem-level effects of sea star wasting disease to the broader public. The studies on this model system will lead to a better understanding of how other ecosystems may resist or be vulnerable to human activities (e.g., fishing, hunting and habitat destruction) that asymmetrically influence top predators.

Diseases that threaten the health of predators can reduce their top-down influence and thus lead to significant changes in ecosystem structure. In 2013-15, sea star wasting disease (SSWD) devastated populations of Pisaster ochraceus, the original keystone predator, along the west coast of North America in one of the most extensive marine disease events ever recorded. This project will leverage this unprecedented outbreak to test and extend keystone predation theory by documenting and explaining the temporal pace, geographical extent, and spatiotemporal co-occurrence of ecosystem recovery from SSWD. The disease event also provides an opportunity to test the resistance and resilience of a well-studied ecosystem at an unprecedented scale. At each of 14 sites, the investigators will quantify processes that underlie potential resistance of the system to loss of sea stars (prey recruitment and colonization, mussel growth, predation intensity, facilitative interactions among sessile organisms, and the effect of alternative predators). In the latter experiments, the PIs will conduct caging exclusion experiments to test the effects of both larger (e.g., birds) and smaller (e.g., whelks) alternative predators on prey recolonization of cleared plots. The investigators will also conduct a novel set of experiments to manipulate factors affecting facilitation of mussels by barnacles and turf-forming algae. All these empirical studies will be used to parameterize modeling efforts that will explore the longer-term and larger-scale implications of these processes, both for this system and for other ecosystems. Specifically, the PIs will fit a novel spatially-explicit metacommunity model to the empirical data in order to determine the relative importance of intraspecific and interspecific resistance vs. resilience mechanisms for the recovery of intertidal ecosystems following a historical, coastal-scale SSWD disturbance.

NSF abstract:

In recent decades, ocean ecosystems, long thought to be immune to change, have undergone disruptions to their structure, diversity, and geographic range, yet the actual underlying reasons for such changes in oceanic biota are often unclear. Coastal intertidal zones (i.e., the shore between high and low tides) have long served as important ecological model systems because of advantages in accessibility and ease of observation, occupancy by easily studied and manipulated organisms of relatively short lifespans, and exposure to often severe environmental conditions. This research will address the stability of a well-known rocky shore system along the Oregon and California coasts. Prior long-term research indicates that, although casual observation suggests these systems are stable, in fact, they may be on the cusp of shifting into another state, losing iconic organisms like mussels and sea stars, and becoming dominated by seaweeds. These changes might be comparable to losing trees and large predators from terrestrial systems. This study would result in the training of undergraduates and graduate students, including individuals from under-represented groups. Additionally, this study would include outreach to the general public.

The researchers will focus particularly on impacts of increasing and more variable warming on community recovery. For example, climate oscillations (e.g., El Niño), coastal upwelling, and particularly temperature have all changed in recent decades in ways leading to increased stress on intertidal biota. In apparent response, coastal ecosystems evidently have become less productive, organismal performance (growth, reproduction) has declined, and key dynamical processes (species interactions) have weakened. The new research will pursue these strong hints of an impending “tipping point” by (1) continuing the projects that led to the insights of increasing instability, (2) adding new projects that will pinpoint ecological changes, and (3) expanding the region of work to include locations in California. Research will assess whether or not sea stars recover from wasting disease, experimentally test if species interactions are indeed weakening, quantify the annual inputs of new prey and changes in abundance, diversity, stability, and resilience of intertidal communities, and document changes in the physical environment. Using field observations and experiments, the research will provide insight into impacts of environmental change, particularly warming, on the future of coastal ecosystems, and more generally, into possible future states of Earth’s ecosystems. Using these data, we will test the hypothesis that direct and indirect effects of climate change are driving, or may drive these systems into new, alternative states.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

The Partnership for Interdisciplinary Studies of Coastal Oceans is a long-term ecosystem research and monitoring program established with the goals of: 

• understanding dynamics of the coastal ocean ecosystem along the U.S. west coast
• sharing that knowledge so ocean managers and policy makers can make science based decisions regarding coastal and marine stewardship
• producing a new generation of scientists trained in interdisciplinary collaborative approaches

Over the last 10 years, PISCO has successfully built a unique research program that combines complementary disciplines to answer critical environmental questions and inform management and policy. Activities are conducted at the latitudinal scale of the California Current Large Marine Ecosystem along the west coast of North America, but anchored around the dynamics of coastal, hardbottom habitats and the oceanography of the nearshore ocean – among the most productive and diverse components of this ecosystem. The program integrates studies of changes in the ocean environment through ecological monitoring and experiments. Scientists examine the causes and consequences of ecosystem changes over spatial scales that are the most relevant to marine species and management, but largely unstudied elsewhere.

Findings are linked to solutions through a growing portfolio of tools for policy and management decisions. The time from scientific discovery to policy change is greatly reduced by coordinated, efficient links between scientists and key decision makers.

Core elements of PISCO are:

• Interdisciplinary ecosystem science
• Data archiving and sharing
• Outreach to public and decision-making user groups
• Interdisciplinary training
• Coordination of distributed research team

Established in 1999 with funding from The David and Lucile Packard Foundation, PISCO is led by scientists from core campuses Oregon State University (OSU); Stanford University’s Hopkins Marine Station; University of California, Santa Cruz (UCSC); and University of California, Santa Barbara (UCSB). Collaborators from other institutions also contribute to leadership and development of PISCO programs.  As of 2005, core PISCO activities are funded by collaborative grants from The David and Lucile Packard Foundation and the Gordon and Betty Moore Foundation. Core support, along with additional funding from diverse public and private sources, make this unique partnership possible.

The Partnership for Interdisciplinary Studies of Coastal Oceans is a long-term ecosystem research and monitoring program established with the goals of: 

• understanding dynamics of the coastal ocean ecosystem along the U.S. west coast
• sharing that knowledge so ocean managers and policy makers can make science based decisions regarding coastal and marine stewardship
• producing a new generation of scientists trained in interdisciplinary collaborative approaches

Over the last 10 years, PISCO has successfully built a unique research program that combines complementary disciplines to answer critical environmental questions and inform management and policy. Activities are conducted at the latitudinal scale of the California Current Large Marine Ecosystem along the west coast of North America, but anchored around the dynamics of coastal, hardbottom habitats and the oceanography of the nearshore ocean – among the most productive and diverse components of this ecosystem. The program integrates studies of changes in the ocean environment through ecological monitoring and experiments. Scientists examine the causes and consequences of ecosystem changes over spatial scales that are the most relevant to marine species and management, but largely unstudied elsewhere.

Findings are linked to solutions through a growing portfolio of tools for policy and management decisions. The time from scientific discovery to policy change is greatly reduced by coordinated, efficient links between scientists and key decision makers.

Core elements of PISCO are:

• Interdisciplinary ecosystem science
• Data archiving and sharing
• Outreach to public and decision-making user groups
• Interdisciplinary training
• Coordination of distributed research team

Established in 1999 with funding from The David and Lucile Packard Foundation, PISCO is led by scientists from core campuses Oregon State University (OSU); Stanford University’s Hopkins Marine Station; University of California, Santa Cruz (UCSC); and University of California, Santa Barbara (UCSB). Collaborators from other institutions also contribute to leadership and development of PISCO programs.  As of 2005, core PISCO activities are funded by collaborative grants from The David and Lucile Packard Foundation and the Gordon and Betty Moore Foundation. Core support, along with additional funding from diverse public and private sources, make this unique partnership possible.

Long Term Research in Environmental Biology (LTREB)

Supports research for a period of 10 years or longer to generate an extended time series of data with a focus on evolutionary biology, ecology and ecosystem science.

Synopsis
The Long Term Research in Environmental Biology (LTREB) Program supports the generation of extended time series of data to address important questions in evolutionary biology, ecology, and ecosystem science. Research areas include, but are not limited to, the effects of natural selection or other evolutionary processes on populations, communities, or ecosystems; the effects of interspecific interactions that vary over time and space; population or community dynamics for organisms that have extended life spans and long turnover times; feedbacks between ecological and evolutionary processes; pools of materials such as nutrients in soils that turn over at intermediate to longer time scales; and external forcing functions such as climatic cycles that operate over long return intervals.