Can an endangered plant help wildlife escape rising seas?

On a recent sunny day, we pounded large wooden branches into the sand and mud next to newly planted shrubs at a salt marsh in a northern part of San Francisco Bay. Our research lab, led by Dr. Katharyn Boyer at San Francisco State University’s Estuary & Ocean Science (EOS) Center, was testing whether an endangered plant with a propensity to climb can help provide endangered animals with refuge from increasingly rising seas.

High tide is a dangerous time for the animals that inhabit our coastal salt marshes. These environments are full of flat expanses with low-lying vegetation — and when they flood with water, small animals living there become easy pickings for raptors flying above, as well as roving foxes and coyotes. That danger is likely to increase as a result of global warming. Some bay marshes will not be able to build sediment fast enough to keep pace with the accelerating rise in sea levels, and high tides will flood the marshes more frequently.

In the spirit of Bay Area innovation, we’ve been seeking creative solutions to help the region adapt to these changing environmental conditions. One solution comes in the form of a plant: California sea blite. This federally endangered succulent disappeared from San Francisco Bay in the 1960s, but still remains in limited numbers in Morro Bay (near San Luis Obispo). It’s a large wetland shrub that will grow even taller given something to climb, such as a large log that has washed in with the tides, or even a fence or an oak tree.

If California sea blite can be encouraged to grow taller than flooding waters, the canopies of its branches can provide places where small wildlife, such as the endangered salt marsh harvest mouse and California Ridgway’s rail, can escape the water and remain hidden during high tides. In the past, local coastal marshes had much more woody debris that a plant like this could have climbed. Today, however, bridge and flood-control maintenance on small streams leading into San Francisco Bay reduce the wood that reaches downstream marshes.

As scientists focused on ecological restoration, we’re working to produce similar structures as a restoration strategy. By installing arbors made from discarded branches next to California sea blite, we are harnessing the plant’s natural ability to climb on woody branches. Also, since it’s a fast-growing succulent, it is well-adapted to surviving the droughts that will become increasingly common with our warming climate.

This spring, we planted California sea-blite, grown from Morro Bay plants at the EOS Center. They were planted at Blackie’s Pasture in Tiburon and at Giant Marsh along the north Richmond shoreline. Early results indicate that the arbors installed help the plants grow taller and larger.

We’re also experimenting with alternative arbor designs and figuring out the ideal conditions for growing young California sea blite plants. Results from these experiments will help us understand the best ways to recover California sea-blite from its local extinction in the San Francisco Bay and use it in restoration projects. It is important to act now. Since the 1800s, 90 percent of the salt marshes in San Francisco Bay have been lost to urban and agricultural development. In addition to providing a home to wildlife, this ecosystem acts as the first defense against storms, flooding and coastal erosion. We rely on these habitats to protect our neighborhoods, freeways and airports from strong storm surges and rising seas that can flood our cities.

Our project is just one example of “nature-based infrastructure,” shoreline enhancements that use nature to reduce the impacts of sea level rise while increasing habitat for wildlife. Returning an endangered plant to the shores of the bay while adding a tool to our climate change resiliency toolkit is an exciting prospect. Amidst the urgency, we are hopeful.

This article was written by San Francisco State University’s Estuary & Ocean Science Center graduate student Kelly Santos and research technician and Boyer Lab manager Melissa Patten, with input from Professor of Biology Katharyn Boyer and our colleague Peter Baye, a coastal ecologist. Our lab is focused on the ecology and restoration of coastal habitats, especially tidal marshes and seagrass beds. This column is one of an occasional series about the Bay and sea around us through the eyes of researchers at the center.

Wire Service

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