This post was contributed by a community member. The views expressed here are the author's own.

Baseball has been described as “a game of inches.” Just a fraction of an inch up or down, where the bat strikes the ball, determines whether the hitter’s swing produces a ground out, base hit or fly ball.

Tidal wetlands are also a game of inches for the wildlife that compete for space. Where the ocean tides reach land, a few inches of land elevation, relative to sea level, determines whether the resulting habitat is vegetated saltmarsh, barren mudflat, or open water (subtidal). Within each habitat, a unique assemblage of plants and animals dominate.

The photo below, taken at the San Dieguito Wetlands near Del Mar, one of Ballona's southern sisters, shows two very different habitats adjacent to each other.

On the left, where ocean tides submerge the land most of the time, we see slender, vertical blades of cordgrass. On the right, where an island juts just inches above the high tide’s reach, scraggly pickleweed covers the land. The blue water is subtidal habitat, where water always covers the land.

This small area is an excellent example of how critical the land elevation is for determining tidal wetland habitat. On the left is Low Marsh habitat, while Mid Marsh and High Marsh habitats are on the right.

Cordgrass only grows where tidal inundation occurs most of the time, in Low Marsh. Mid- and High Marsh habitats depend on the tidewaters receding daily and allowing the land to drain most of the time. The dominant vegetation type in southern California tidal wetlands, cordgrass or pickleweed, are each adapted to that particular tidal inundation duration. See the simplified diagram below.

The photo below shows a much larger expanse at San Dieguito displaying the same two habitats: cordgrass Low Marsh dominating the lower elevation center of the basin, while pickleweed covers the higher elevation fringes of the basin. The blue water at center is not subtidal, but rather mudflat habitat, covered with only an inch or two of tidewater. The elevation difference between the three habitats in this photo is less than six inches.

Above: Cordgrass and pickleweed dominate Low- or Mid-Marsh at the San Dieguito Wetlands.

All of the habitat in this photo was constructed - by bulldozers, scrapers and excavators - from pasture land that had been historically infilled. The same approach is planned at Ballona for the 200 acres south of Fiji Way, filled in by mud dredged from Marina Del Rey's construction.

Above: Pickleweed Mid- and High Marsh at Ballona. There is no cordgrass expanse at Ballona because insufficient land exists at the proper elevation, and tide gates prevent the area in this photo from full tidal inundation. The Department of Fish and Wildlife's restoration plan will allow full inundation and create new Low-, Mid- and High Marsh south of Fiji Way.

As we all know, Earth’s climate is warming, melting polar and glacial ice and raising sea level. Depending on the predictive model used, sea levels will rise between several inches or more than three feet over the next hundred years. See the graph of a few model predictions below.

Above: Model predictions of sea level rise along the California Coast. Source: Dan Cayan, Scripps Institute of Oceanography, from The Impacts of Sea Level Rise on the California Coast, Heberger et al., Pacific Institute, 2009. CEC-500-2009-024-F

At every tidal wetland on California’s coast, this sea level rise will change the marsh habitat type and the animal species that depend upon them. As sea level rises, subtidal habitat (open water) will replace mudflats. Low marsh will give way to mudflat, and so on.

Ridgeway’s Rail vs Belding’s Savannah Sparrow

The Belding's Savannah Sparrow is a small bird that exclusively inhabits pickleweed saltmarsh, the higher elevation habitat. Belding's are an endangered species and live at Ballona, San Dieguito and most other southern California tidal wetlands.

Above: The Belding's Savannah Sparrow, perched within pickleweed within the Ballona Wetlands. Photo by Patrick Tyrrell

Ridgeway's Rail (formerly called the Light-Footed Clapper Rail) is a larger hen-like bird that exclusively inhabits cordgrass saltmarsh, the lower elevation habitat. Ridgeway's are also endangered and found at many southern California tidal wetlands. They do not presently exist at Ballona, because Ballona does not have sufficient cordgrass habitat. Ridgeway's likely existed at Ballona in the distant past, before oil production, agriculture and Marina Del Rey destroyed most of the cordgrass areas.

Above: Ridgeway's Rail. U.S. Fish and Wildlife Service photo.

As sea levels rise at wetlands, the Mid-and High Marsh Belding's habitat will be replaced with Ridgeway's habitat. Eventually, Ridgeway's habitat will surrender to subtidal habitat, which is nice for fish but not so nice for either Ridgeway's or Belding's. Both species' numbers will diminish and be confined to the upper elevation fringes of our wetlands over the next century as the sea encroaches. This gradual habitat conversion will occur at every southern California tidal wetland, unless we decide to do something about it.

The California Coastal Commission and local governments are already wrestling with how to manage the coastal impacts of sea level rise. For homes on the beach or on the edge of eroding bluffs, the Commission seems to be leaning toward "managed retreat." Put very simply, if your home is on the beach and will eventually be consumed by sea level rise, the state may buy your home at taxpayer expense for some determined value so you can move elsewhere, but they may not allow you to armor your home to protect it from the rising sea. No doubt, there will be a lot of arguing about this in the coming decades.

What about California's tidal wetlands, their sea-level dependent habitats, and the species they support? Shall we just let nature take its course (acknowledging our human-caused contribution to sea level rise) and watch Belding's habitat slowly surrender to Ridgeway's habitat? Or, should we construct infrastructure such as tide gates, and/or raise the land elevation, to protect the existing habitats? Should we control or manage sea level rise at some California wetlands but not others? Why or why not?

Who gets to decide those statewide policy questions? Do we need to decide them today? Should we leave the decisions to our children and grandchildren? They will be living with and managing the changes. Might they have better ideas than we about what to do?

Dr. David W. Kay served on the Board of Directors of the non-profit Friends of Ballona Wetlands from 2007 until 2015, and served as Board President in 2012-13. He presently serves on the Board of Ballona Discovery Park in Playa Vista. Dr. Kay is a staunch advocate for the state of California's plans to restore the Ballona Wetlands Ecological Reserve.

From 1984 until 2022, Dr. Kay was employed by Southern California Edison Company, exclusively in the company's environmental services organizations. His many responsibilities included restoration of the 440-acre San Dieguito Wetlands near Del Mar. He retired in 2022 as Senior Manager for Major Project Environmental Management at the company, after 38 years of service.

Dr. Kay earned bachelor and masters degrees in biology and a doctorate in environmental science. See Dr. Kay’s Patch Community Contributor profile here.

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