Aramburu Island Ecological Enhancement Project
Aramburu Island is a 17-acre wildlife preserve in Richardson Bay. Like many other areas in the San Francisco Bay region, the island’s habitat has been altered by non-native and invasive plants and a slowly eroding shoreline. The Richardson Bay Audubon Center and Sanctuary and Marin County partnered on a shoreline protection and habitat enhancement project intended in part to make the island more resilient to the impacts of climate change, especially sea level rise and increased coastal storm surges and erosion.
Aramburu Island is a 17-acre wildlife preserve managed by the Marin County Parks and Open Space in Richardson Bay. The island is home to many birds displaced by the November 2007 Cosco-Busan tanker spill of over 58,000 gallons of oil into San Francisco Bay. The island has also been affected by non-native, invasive plants that have altered habitat and disrupted the food chain in Richardson Bay, and the shorelines are slowly eroding. Climate change is expected to exacerbate erosion in the region due to sea level rise and increased frequency and severity of storms. The Richardson Bay Audubon and Marin County conducted a project to make island habitats more suitable for birds and other wildlife through habitat enhancement and shoreline protection measures.
The main project goals, developed in cooperation with Richardson Bay Audubon, Marin County, and community members, were to:
- Reduce erosion along the island’s eastern shoreline. Instead of traditional shoreline hardening measures, the project used soft engineering solutions such as sand and gravel nourishment to stabilize beaches and reduce erosion.
- Increase resilience to sea level rise. The existing topography of the island consists of a sharp divide between upland areas and intertidal habitats, providing little natural resistance to storm surges and sea level rise. The project was designed create a gradual transition zone to buffer wave action and allow for landward migration with sea level rise.
- Enhance bird habitats. Using beach nourishment and stabilization techniques (e.g., introducing large woody debris to increase shoreline complexity), the project aimed to enhance roosting, foraging, and nesting habitats for shorebirds, waterbirds, and wading birds.
- Enhance haul-out habitats for harbor seals. Harbor seals have been historically associated with Aramburu Island. With increasing erosion and human disturbances, seals have deserted the area. The project aimed to improve haul-out site conditions to potentially re-attract harbor seals to the island.
- Enhance rare salt marsh habitats. The project proposed to reintroduce three annual native salt marsh plants––salt marsh bird’s-beak (Chloropyron maritimus ssp. palustre), salt marsh owl’s-clover (Castilleja ambigua), and smooth goldfields (Lasthenia glabrata ssp. glabrata)––to the island to enhance high tidal marsh habitat.
- Restore native vegetation. Many areas of the island have been inundated by non-native and invasive plants. The project aimed to replicate native shoreline vegetation types believed to be adapted to sea level rise, including lowland grassland and sedge meadows and seasonal wetlands.
The main project design objectives were to:
- Enhance existing tidal marsh, grassland, tidal flat, and shoreline habitats on the island to support diverse native vegetation, habitats, and species
- Increase the amount of sand and gravel spit areas for use by shorebirds
- Reduce erosion by employing sand/sediment renourishment efforts
Details on shoreline protection and enhancement techniques can be found in the Aramburu Island Shoreline Protection and Ecological Enhancement Project Draft Enhancement Plan. Construction of the shoreline, wetland, and terrestrial enhancement elements of the project, including burying invasive species, grading of upland areas, and irrigation for dust control, were completed by fall 2012. Additional initiatives, such as invasive species removal, revegetation, scientific monitoring, and shorebird surveys, took place between 2012 and 2017. Richardson Bay Audubon has committed to continue its work with these initiatives on Aramburu Island through 2021. Funding for this effort was provided by the Cosco Busan Oil Spill Settlement Trustee Council, California Regional Water Quality Control Board, Sewerage Agency of Southern Marin, National Fish and Wildlife Foundation, Marin Community Foundation, S.D. Nechtel Jr. Foundation, Mary Crocker Foundation, and the National Oceanic and Atmospheric Administration, among others.
Outcomes and Conclusions
Along with Marin County, Richardson Bay Audubon developed a project to restore, improve, and maintain Aramburu Island habitat. Erosion is already an issue for Aramburu Island and many of the project’s goals directly addressed taking proactive measures to limit or eliminate erosion. Active restoration efforts largely concluded in 2017, while monitoring and public work days continue with the support of Marin County Parks. Since restoration began, Aramburu Island has become a successful nesting site for black oystercatchers (Haematopus bachmani), black-neck stilts (Himantopus mexicanus), and killdeer (Charadrius vociferous). In addition, the enhanced landscape of Aramburu Island includes sand and gravel beaches, tidal marshes, seasonal wetlands, and grasslands, which can support various fish and wildlife.
Gregg, R. M. (2021). Aramburu Island Ecological Enhancement Project [Case study on a project of the Richardson Bay Audubon Center & Sanctuary]. Version 2.0. Product of EcoAdapt’s State of Adaptation Program. Retrieved from CAKE: https://www.cakex.org/case-studies/aramburu-island-ecological-enhancement-project (Last updated August 2021)