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Project Summary / Overview
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 are partnering on a shoreline protection and habitat enhancement project 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 now home to many birds displaced by the November 2007 Cosco-Busan oil tanker spill of over 58,000 gallons into San Francisco Bay. In addition, the island has 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. The Richardson Bay Audubon and Marin County are working to make island habitats suitable for birds and other wildlife through a habitat enhancement and shoreline protection project.
The main project goals, developed in cooperation with Richardson Bay Audubon, Marin County, and community members, are to:
1. Reduce erosion along the island’s eastern shoreline. Instead of traditional shoreline hardening measures, the project uses soft engineering solutions such as sand and gravel nourishment to stabilize beaches and reduce erosion.
2. 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 proposed design would create a gradual transition zone to buffer wave action and allow for landward migration with sea level rise.
3. Enhance bird habitats. Using beach nourishment and stabilization techniques (e.g., introducing large woody debris to increase shoreline complexity), the project will enhance roosting, foraging, and nesting habitats for shorebirds, waterbirds, and wading birds.
4. 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 will aim to improve haul-out site conditions to potentially re-attract harbor seals to the island.
5. Enhance rare salt marsh habitats. The project proposes 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.
6. Restore native vegetation. Many areas of the island have been inundated by non-native and invasive plants. The project aims 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 are 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.
Project Outcomes and Conclusions
Along with Marin County, Richardson Bay Audubon is working to restore and improve the Aramburu Island habitat. Climate change is expected to cause sea level rise and increased frequency and severity of storms in the area. Erosion is already an issue for the island and many of the project’s goals directly address taking proactive measures to limit or eliminate erosion. In addition, the enhanced landscape of Aramburu Island would include sand and gravel beaches, tidal marshes, seasonal wetlands, and grasslands, which can support various fish and wildlife.