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One sunny afternoon this June, an eagle-eyed summer camper knelt on the pebbly beach of the Richardson Bay shoreline. Among a tangle of washed-up eelgrass, bryozoans, and bright green sea lettuce, they spotted something small and shimmering: tiny, translucent bubble-like structures clinging to the strands like dewdrops. Upon closer inspection, and a little help from an ��������Ƶ Adventure Camp counselor’s phone camera, the discovery came into focus: clusters of jack silverside (Atherinopsis californiensis) eggs, delicately nestled in the algae and blades of eelgrass. The camper lit up, not just with curiosity, but with the spark of a budding naturalist seeing how even a strand of eelgrass holds life.

This quiet moment captured a larger truth: eelgrass meadows are foundational to the health of Richardson Bay and the San Francisco Bay Area at large. Eelgrass (Zostera marina L.) is a keystone species that fuels the entire estuarine food web. Its long, ribbon-like blades slow down waves, stabilize sediment, and improve water clarity. Of equal importance, eelgrass provides essential habitat for invertebrates, nursery grounds for juvenile fish like jack silverside, leopard sharks, and bat rays, and foraging opportunities for migratory waterbirds making their annual journey down the west coast. Even species we don’t always see, such as Pacific herring (Clupea pallasii) and eelgrass seahares, depend on these underwater meadows for spawning and shelter.

Beyond its crucial role as habitat and food source for numerous marine species, eelgrass is remarkable for the many specialized adaptations that allow it to thrive in the dynamic, shifting environments of shallow coastal bays, estuaries, and marshes. A marine angiosperm—a true flowering plant, not a seaweed or algae—eelgrass forms its extensive beds, or meadows, in soft sand and mud habitats. Eelgrass thrives in temperate waters from the low intertidal zone to depths of about 6 meters. As a euryhaline species, eelgrass can live in a wide range of salinities and is capable of growing near stream mouths where there is freshwater at low tide, but it cannot grow in persistent fresh water. The plant reproduces asexually through the growth of root-like rhizomes that are the foundation of these eelgrass meadows, but can also reproduce sexually by seed germination. Male and female flowers are present on the same plant but mature at different times, which prevents self-fertilization; male plants release their long, filamentous pollen into the water column to be carried by wave action over to female flowers where fertilization occurs. After seed-bearing shoots develop post-fertilization, they break off from the plant and float to the surface, often creating floating aggregations of reproductive shoots and blades called ‘wrack,’ which make long-range seed dispersal possible. When the reproductive shoots release their seeds, they sink to the bottom of the bay before germinating (California Department of Fish and Wildlife, n.d.).

This intricate reproductive strategy not only supports the persistence of eelgrass meadows, but also plays a vital role in sustaining broader estuarine ecosystems, including those that overlap with key periods of fish spawning and bird migration. The Richardson Bay ��������Ƶ Sanctuary’s annual closure from October 1 to March 31 coincides with both peak Pacific herring activity and the migration of shorebirds and waterbirds along the Pacific Flyway, a major north-south migration route for birds in the Americas that extends from Alaska to as far south as Patagonia. Every year, migratory birds will travel some or all of this distance both in the spring and the fall as they head to breeding grounds or overwintering sites, as well as to follow critical food resources, such as Pacific herring. Though they are a coastal schooling species, found at a large range of ocean depths throughout most of the year, adult Pacific herring migrate into estuaries and bays to breed, with timing varying by latitude (NOAA, n.d.). Pacific herring in California will typically lay their eggs from November through March; in the San Francisco Bay Area, spawning can occur in multiple events within this timeframe. Spawning aggregations are most common in bays and estuaries, with peak activity between December and February. Bird predators of herring spawn, such as diving ducks like surf scoters (Melanitta perspicillata), may incidentally ingest eelgrass while consuming the eggs deposited on it during spawning events (California Department of Fish and Wildlife, n.d.).

Eelgrass meadows offer a wide range of ecosystem services that are essential to the health of coastal environments in addition to providing critical nursing and foraging grounds that sustain estuarine food webs. They improve water clarity by trapping sediments, sequester carbon and nutrients, and buffer shorelines against erosion. Yet these benefits are increasingly threatened by both local and global pressures. Coastal development and degraded water quality, particularly turbidity and nutrient pollution, are among the most significant drivers of seagrass decline worldwide (Waycott et al., 2009). In Richardson Bay specifically, eelgrass has historically flourished due to its shallow depth, relatively clear waters, and soft sediment substrate. However, a 2021 Restoration & Adaptive Management Plan for Richardson Bay emphasizes that these advantages are increasingly undermined by mechanical damage from anchor-out vessels, which drag anchors and churn up sediments, consequently reducing light penetration and physically breaking apart eelgrass beds (Richardson Bay Regional Agency & San Francisco Bay Conservation and Development Commission, 2021). These vessels have also been identified as a major source of water pollution due to mismanaged waste, prompting local agencies to begin phased removal efforts in 2021 (Thapa, 2024). Fortunately, despite these challenges, Richardson Bay remains one of the last healthy eelgrass sanctuaries in the San Francisco Bay Area, with the most genetic diversity and the second-largest area of any local eelgrass bed (Thapa, 2024). For these reasons, there is such value and potential for restoration efforts that will enhance these eelgrass beds to protect and expand upon habitat, improve water conditions, strengthen shoreline resilience, and promote local biodiversity. These ecosystem services are critical for the stability and wellbeing of not just the bay’s native species, but also the coastal communities and economies tied to them.

Recent local protections have prompted the steady recovery of this ecosystem. In the spring and early summer of 2024, researchers from San Francisco State’s Estuary and Ocean Science Center, staff at the Richardson Bay ��������Ƶ Center and Sanctuary, and restoration specialists from the environmental consulting firm Merkel & Associates initiated the replanting of eelgrass in areas of Richardson Bay damaged by mooring scars. This work was made possible through a $2.8 million grant from the Environmental Protection Agency’s San Francisco Bay Water Quality Improvement Fund. As part of an EPA program funded by the federal Bipartisan Infrastructure Law, part of a larger initiative funded by the federal Bipartisan Infrastructure Law to support long-term ecological restoration in the region (U.S. Environmental Protection Agency [EPA], 2024), this grant will sustain this project over the next four years. The project aims to restore 15 acres of eelgrass over the next four years, enhancing habitat for invertebrates, fish, and foraging birds while simultaneously improving water quality and shoreline resilience. By filling in bare patches left by decades of anchoring, this effort not only improves the structural integrity of existing eelgrass beds but also promotes connectivity between meadow fragments, which research has shown to be essential for maximizing the ecological benefits of seagrass systems (Thapa, 2024; Waycott et al., 2009). These local actions, rooted in collaborative science and community stewardship, offer a hopeful model for coastal habitat recovery in the face of mounting climate and development pressures.

Hope can also be found in our everyday observations of this vibrant ecosystem. When Richardson Bay reopened to recreational activities this spring, our high school interns, the ��������Ƶ Youth Leaders (AYLs), had the opportunity to witness the resilience and richness of eelgrass habitat firsthand during two immersive kayaking trips across the bay as part of their local ecology education. On the first trip, we paddled to Aramburu Island, a nearby habitat restoration site just across from the Richardson Bay ��������Ƶ Center, while the second outing took us along the Sausalito waterfront. From the water, the AYLs observed double-crested cormorants diving for fish, great blue herons stalking the shallows, and harbor seals playfully and inquisitively following our kayaks, all evidence of the quiet productivity teeming in these submerged meadows. But more of the magic was hidden just below the surface. As the AYLs glided over swaying beds of eelgrass, we encouraged them to imagine what else might be thriving below: marine snails, baby crabs, and even juvenile halibut, all interconnected in this dynamic web of life.

As one Youth Leader reflected after we returned to shore, “Kayaking to Aramburu Island deepened my curiosity and understanding of this ecosystem.” Another remarked, “Kayaking was a great way to connect with marine life through a new lens, as it allowed me realize how much we’ve built around this ecosystem.” That’s exactly the kind of connection we strive to foster at Richardson Bay ��������Ƶ: a sense of wonder and stewardship rooted in personal experience. Whether it’s a kayak trip or the discovery of a handful of eggs found on a bit of wrack, every encounter with eelgrass offers a reminder that our efforts to understand and protect even the most unassuming species have impacts that ripple outward to sustain entire ecosystems.

References

California Department of Fish and Wildlife. (n.d.). Eelgrass. Marine Species Portal. Retrieved June 30, 2025, from

EPA. (2024, March 12). EPA announces over $52 million for San Francisco Bay restoration projects as part of Investing in America agenda [Press release]. U.S. Environmental Protection Agency.

Thapa, A. (2024, June 20). In the Name of Eelgrass. Bay Nature.

Waycott, M., Duarte, C. M., Carruthers, T. J. B., Orth, R. J., Dennison, W. C., Olyarnik, S., ... & Williams, S. L. (2009). Accelerating loss of seagrasses across the globe threatens coastal ecosystems. Proceedings of the National Academy of Sciences, 106(30), 12377–12381.