Why We Can’t Afford to Lose Mission Bay’s Marshlands
Adapted from Sketches Magazine article “Update: ReWild Mission Bay,” by LaTresa Pearson
Kendall-Frost Marsh Reserve is amongst the last remaining natural wetlands in Mission Bay.
Once, a vast estuary complex extended from the mouth of the San Diego River, comprising more than 4,000 acres of wetlands. Today, the Kendall-Frost Marsh is nearly all that remains, representing part of just 40 acres of salt marsh still existing in this area. Despite its small size, this wetland area is vitally important, as wetlands like the Kendall-Frost Marsh Reserve provide wildlife and humans with critical services that can’t be replicated by other land types. This is why wetlands are so important to us here in San Diego.
- Wetlands like the Kendall-Frost Marsh provide critical habitat to native and endangered species, such as the endangered Ridgway’s Rail.
- Marshes store carbon, helping us fight climate change. Marshes also prevent flooding, helping us mitigate the impacts of rising sea levels.
- Healthy wetlands also provide us with clean water and prevent erosion.
- Protecting and expanding wetlands like those in Mission Bay is vitally important to ensuring we can still depend on their important ecological services.
Ecological Services of Wetlands
We depend on healthy wetlands more than you may realize. Here’s how.
Healthy coastal wetlands and other coastal ecosystems like eelgrass are valuable tools in the fight against climate change because they capture carbon and store it in their dense, muddy sediment, reducing the amount of greenhouse gas in the atmosphere. Tidal marshes can store, or sequester, carbon at rates two to four times greater than mature tropical forests, according to the International Blue Carbon Initiative, a global program focused on mitigating climate change through the conservation and restoration of coastal and marine ecosystems. Tidal marshes have a lot of plants, and those plants take carbon out of the air through photosynthesis and store it in their shoots and flowers above the ground, and in their roots and rhizomes below the ground.
Blue carbon researchers from Scripps Institution of Oceanography estimate that the Kendall-Frost Marsh is storing between 2,400-6,000 tons of carbon. That’s equivalent to the carbon released from around 4,000 round-trip flights between LA and New York City! But when wetlands are dredged like they were in the construction of Mission Bay Park, they release that carbon into the atmosphere, contributing to climate change rather than helping to reduce it.
Wetlands also build up sediment, which creates a buffer between rising waters and urban development, preventing flooding in coastal communities caused by storm surges and sea-level rise.
Healthy wetlands act as a natural water filter, helping to preserve clean water. The Mission Bay wetlands improve the water quality of Mission Bay and surrounding waters by absorbing nutrients and filtering or trapping pollutants from urban runoff before they can enter the ocean.
While we don’t often think of marshes as a public health measure, they provide a critical public health service: clean water. Sunbathers, surfers, and swimmers on Mission Beach may not realize it, but Kendall-Frost Marsh is helping them stay healthy! As clean water is increasingly threatened by urban runoff and other forms of pollution, the marshes become even more critical as a natural water filtration system.
Healthy wetlands help us keep it together – literally – by guarding against erosion. Wetlands cushion the impact of waves, protecting delicate areas from breaking down. Marshes also trap sediment that would otherwise wash away. As sea levels rise – and development continues to encroach on coastal wetlands – it’s vitally important that we maintain this natural protective barrier.
Protection of Biodiversity
Finally, salt marshes, mudflats, and sea grasses found in wetlands provide critical habitat for a variety of animals and plants. Native species abound in the Kendall-Frost Marsh; The coastal sage scrub is filled with the soft pink and cream blossoms of California Buckwheat, while close to the water you’ll find rambling seablite, saltgrass, arrowgrass, saltbush, saltmarsh daisy, California sea lavender, and saltwort. Yellow-green cordgrass interspersed with succulent pickleweed take over in the lower marsh, providing critical habitat for the federally listed endangered Ridgway’s Rail and the state-listed Belding’s Savannah Sparrow, which is only found in the last few remaining salt marshes that dot the Southern and Baja California coastline. In the mudflats, a variety of shorebirds thrive, while underwater eelgrass beds lie just beyond, out of sight, serving as nurseries to fish like the California Halibut.
Mission Bay’s coastal wetlands supply vital food, refuge, and nursery habitat for more than 75 percent of fishery species. They also protect biodiversity by providing essential habitat to the highly adapted and endangered species that live in them, as well as providing refuge for birds migrating along the Pacific Flyway.
The Time Is Now
Despite the many ecosystem services coastal wetlands provide, they are disappearing at an alarming rate. Southern California has already lost about three-quarters of its salt marshes, and many of the rest are threatened by the impacts of development and rising sea levels. Even some existing marshes like the Kendall-Frost Marsh may become too small to properly provide these ecosystem services anymore.
Preserving and managing sites like Mission Bay’s wetlands today is crucial to ensuring a livable future. Learn how you can take action.
Read the whole article in our Sketches Summer 2022 issue.
Photo courtesy of Karen Straus and Roy Little.