Eelgrass (Marina Zostera) is a marine flowering plant that can grow completely submerged in water. It can be found along our California coastline, mainly thriving in shallow bays and estuaries. Large eelgrass beds can be found in Santa Cruz, Channel Islands, San Diego Bay and even in our local beaches and estuaries in Orange County. Eelgrass prefers the calm waters and muddy, sandy bottoms of our bays and can survive in varying levels of salinity. It is a foundation species, meaning that it is essential in the creation of its habitat and the surrounding biodiversity. Eelgrass performs many valuable ecosystem functions that make it vital to our coastal environment. It acts as a shelter and spawning ground for various species including crab, salmon, and Pacific Herring, can protect our shores from natural erosion, and helps to balance our carbon emissions!
Eelgrass is a key part of a healthy and booming marine ecosystem. Eelgrass relies heavily on sunlight to conduct photosynthesis, serving as its source of energy and subsequently providing oxygen to the surrounding water. It plays an important role in the food web, feeding migratory bird species, herbivores like sea turtles and various invertebrates. When eelgrass dies, it sinks to the mud floor and provides organic matter for bottom-dwelling decomposers. Not only is it a source of sustenance, but eelgrass is also an important nursery site because it provides habitat for juvenile fish including Pacific salmon and Lingcod and is an important spawning ground for Pacific Herring (CA Department of Fish and Game). The beds of grass provide protection and area to forage for the young fish and invertebrates like Dungeness crab. Snails, sea stars, anemone and crabs can also be found living amongst the beds of eelgrass.
As a foundation species, eelgrass serves as a marker indicating the health of estuaries. The abundance of eelgrass in an area can give us some information about the quality of the water. It is sensitive to stressors like pollution, which can affect water clarity and block sunlight from the plant, making it more difficult for the plant to grow. When eelgrass beds are damaged, the organisms that rely on it for food and shelter may not survive or will move out to find another ecosystem with more abundant resources. Eelgrass supports life in the water and serves as a protective barrier between human activity and the ocean. Due to its presence along shorelines and in the shallow water, eelgrass filters runoff and nutrients entering our estuaries and bays further aiding the health of these marine environments.
A plethora of anthropogenic practices are threatening eelgrass populations in California. A majority of the eelgrass that once inhabited the southern coast has been depleted because of coastal development and dredging. Pollution and water quality changes also affect the species because it is sensitive to accessibility to light. You may be wondering what would happen if eelgrass populations were lost. In the 1930s, eelgrass wasting disease wiped out about 90% of eelgrass populations on the Atlantic coasts of Europe and the US (CA Department of Fish and Game). What followed was a decline in brant geese populations and scallop populations, as well as the extinction of eelgrass limpet (Lottia alveus). All these species rely on eelgrass for survival, so the disappearance of eelgrass directly affects the health and population sizes of these species.
It is evident that eelgrass serves many important ecosystem functions to marine ecosystems, but what does it do for humans? Eelgrass can protect our shorelines from coastal erosion and absorb wave shock by helping to lock sediment in place. As sea levels rise, eelgrass can help to mitigate the effects that it has on our California coast. It is a much more natural and sustainable solution than other man-made strategies like concrete walls that actually cause faster rates of coastal erosion. Coastal development also increases coastal erosion, and beautiful waterfront homes and buildings are at great risk of instability and flooding due to erosion and harsh waves from rising sea levels. Eelgrass also has the ability to sequester carbon up to 35 times the rate of tropical rainforests (NOAA Fisheries). The ability to sequester carbon makes it a potential solution to our rising fight against climate change. Many scientists are turning their attention to seagrass bed restoration and conservation and how it can be used in meeting climate action goals. Many countries participating in the United Nations Environment Program have included seagrass beds in their plans for mitigating and adapting to the changing climate.
Eelgrass was designated as an Essential Fish Habitat (EFH) and a Habitat of Particular Concern by the federal government, under the Magnuson-Stevens Fishery Conservation and Management Act in 1996. As an EFH, federal agencies are required to consult with the National Oceanic and Atmospheric Administration (NOAA) fisheries following the California Eelgrass Mitigation Policy and Implementing Guidelines (CEMP) to avoid and mitigate their effects on eelgrass (UN Environment Program). The initiative includes efforts towards eelgrass restoration to ensure the growth and protection of lost original habitats. Countries globally are beginning to experiment with large scale eelgrass restoration projects, but there is much research to still be done about the efficiency and success rate of restoring.
In Orange County there are local efforts to restore eelgrass to the Upper Newport Bay led by a partnership between Orange County Coastkeeper (OCCK), Rick Ware, President and Senior Marine Biologist of Coastal Resources Management, Inc. and the California Department of Fish and Wildlife. Since 2012, the program has planted 300 square meters (or 0.0741 acres) of eelgrass which has grown to about one acre of eelgrass in the bay, a 13.5x increase (Orange County Coastkeeper). With the success of the ongoing projects comes ecological, economic, and educational benefits that will serve generations to come. The presence of a stable eelgrass habitat brings species diversity and health in the estuary and restores important ecosystem services. A healthy estuary adds to the value of the bay for recreational activities and increases opportunities for education! You can stay up to date with the restoration’s progress on OCCK’s website and join us at OC Habitats for more opportunities for restoration at Upper Newport Bay or just to learn more about the habitat’s diversity!
Resources
Ramey, K. (2008). 16 Eelgrass, Zostera marina - Status of Fisheries Report 2008. CA Department of Fish and Game. https://nrm.dfg.ca.gov/FileHandler.ashx?DocumentID=34429