Kelp Monitoring and Recovery in the Puget Sound
Kelp forests have experienced significant losses worldwide, including in Washington State’s Puget Sound, due to both anthropogenic and environmental factors. Declines have been attributed to urbanization, stormwater runoff, and agricultural practices that result in increased nutrient loads, pollution, and altered coastal sedimentation rates, which in turn affect the ability of kelp to photosynthesize. Apart from human activities, changes in environmental factors like extreme weather events, rising water temperatures, competition from the invasive seaweed Sargassum, and overgrazing by urchins and kelp crabs can also impact kelp survival.
Concerns about kelp decline in Puget Sound have prompted organizations throughout the state to band together to monitor and collect data on its presence, abundance, density, and extent. This ongoing research and data collection, supported by numerous organizations and partners, will highlight areas of Puget Sound where kelp populations are healthy and thriving or vulnerable and in decline and identify active measures to ensure species protection and recovery.
The coast of Washington State supports 22 kelp species, more than anywhere else in the world. Bull kelp (Nereocystis luetkeana) and giant kelp (Macrocystic integrifolia), two species of brown algae that form underwater canopies similar to terrestrial forests, are common sights to many beachgoers, divers, and kayakers. Kelp provides habitat, food, and protection for marine species, offers coastal protection against waves, and plays a role in nitrogen cycling. Because kelp are annual species, they can be particularly susceptible to environmental changes that affect their growth and reproduction.
The Washington Department of Natural Resources (DNR) has been monitoring the canopy-forming bull and giant kelp populations along the outer coast of Puget Sound and the Strait of Juan de Fuca annually since 1989 through their Nearshore Habitat Program, which has helped set the stage for monitoring in other parts of Washington.
Within Puget Sound, a lack of baseline data about the status of bull and giant kelp populations meant that any trends were not well understood or documented. To address this knowledge gap, researchers, Tribal partners, citizen scientists, and volunteers worked together to monitor kelp beds throughout Puget Sound, conduct baseline surveys, and gather annual data to support the development of a strategic plan for kelp protection and recovery.
This collaborative work has relied upon the joint and ongoing effort of multiple organizations and partnerships, including the Washington State Department of Natural Resources, Samish Indian Nation, Northwest Strait Commission, University of Washington’s Friday Harbor Laboratories, Washington Sea Grant, and Marine Agronomics, LLC.
In 2015, the Northwest Straits Commission (NW Straits) launched an annual survey of bull kelp beds in the northern stretches of Puget Sound using a kayak-based survey protocol with the help of seven Marine Resources Committees (MRCs) representing Clallam, Jefferson, Island, San Juan, Snohomish, Skagit, and Whatcom counties. Annual kayak surveys have been conducted since then by volunteers from June to September during peak annual kelp growth to record the location and extent of kelp beds. The data have been incorporated into several databases and reports and have informed other projects like the aerial image photography project led by the DNR and NW Straits.
The primary motivations for the aerial image photography project were to enhance the kayak-based kelp monitoring program and contribute to the strategic goals laid out in the 2020 Puget Sound Kelp Conservation and Recovery Plan (Kelp Plan) and subsequent status update report, which provide a framework for coordinated research and management actions. Imagery from drone and fixed-wing platforms was compared to kayak survey data. Comparisons showed agreement about the location and distribution of the kelp beds at each site but significant differences in the estimated area. Ongoing refinement of both methods will continue, but the results support the idea that kayak surveys and aerial imaging platforms can be used to capture meaningful data about the distribution and abundance of kelp forests in Puget Sound.
In the southern Puget Sound, a 2021 peer-reviewed study assessed changes to bull kelp forests over the past 145 years. Kelp forests along the wave-sheltered southern shorelines have experienced significant declines, which is attributed to a greater prevalence of and sensitivity to environmental stressors. In contrast, kelp forest abundance in areas of Puget Sound with greater wave exposure and closer proximity to the open ocean has remained relatively stable over recent decades. Historically, however, data records and Tribal accounts suggest that bull kelp density and extent have significantly decreased throughout Puget Sound overall. It is still being determined how climate change impacts may affect kelp species throughout the region, including the numerous understory kelp species for which even less is currently known.
The Kelp Forest Monitoring Alliance of Washington State released the first statewide assessment of floating kelp in Puget Sound in 2023. The assessment is part of the WA Floating Kelp Indicator, which keeps track of long-term trends in the extent of canopy-forming kelp forests to inform management and research actions. The report found that floating kelp bed extent ranges from stable to substantial decline and total loss. The most stable populations currently occur along the North Coast and Eastern Strait, while the most unstable occur in the South and Central Puget Sound, with some areas showing a total loss.
Most recently in 2023, the Kelp Policy Advisory Group published 11 policy recommendations that are intended to provide guidance on the implementation of existing rules and regulations related to kelp conservation and recovery in Puget Sound.
Outcomes and Conclusions
Data sets from the kayak surveys, aerial imagery photography project, and other DNR projects and research have been incorporated into several databases and reports, including:
- Kelp Monitoring Data Viewer and StoryMap about kelp along the outer coast
- SoundIQ, a northern regional kelp database
- Statewide Floating Kelp Indicator and interactive map
- Shoreline Monitoring Database
- The dynamics of kelp forests in the Northeast Pacific Ocean publication (2017)
- Puget Sound Kelp Conservation and Recovery Plan (2020)
- Long-term changes to kelp forests in the South Puget Sound publication (2021)
- Aerial photography StoryMap (2021)
- Aerial imaging project report (2021)
- Kayak-based Survey Protocol (updated in 2023)
- Data synthesis report of kayak surveys (2023)
- Floating Kelp Monitoring in Washington State: Statewide Summary Report (2023)
- Kelp policy Recommendations for WA State (2023)
These databases and resources will be updated as project researchers collect additional data. Ongoing research will help fill monitoring gaps and improve our understanding of kelp abundance and extent and the actions needed to ensure its protection and recovery in Puget Sound. A main goal is to continue to learn from Tribal, volunteer, academic, and government perspectives and further expand community awareness and participation throughout Washington.