Scientists seek to bring San Francisco's aging seawall to life
The San Francisco Embarcadero is full of eye-catching destinations: from Fisherman's Wharf, Pier 39, the Exploratorium, and the iconic Ferry Building to name just a few iconic stops.
But these days, down by the water, what's grabbing a lot of attention is what you don't see: underwater, the Bay supports an incredibly diverse ecosystem.
"I got out of the water after my first dive, and I felt like saying 'Hey do you people… walking around on the sidewalk... do you know what's going on down there?'" exclaimed scientist Chela Zabin. Zabin is an ecologist at the Smithsonian Environmental Research Center or SERC for short.
Unfortunately, sea level rise, extreme weather, and warming temperatures are posing a threat to native marine species. Not only that, but expert inspections of the seawall recommend repairs to the century-old structure.
Now an innovative experiment may offer a beneficial solution.
Along the aging seawall, at three different locations. a team of scientists from SERC have placed some very unusual tiles. The tiles are installed at the Pier 45 Breakwater, the Agricultural Building Seawall, and the South Beach Harbor East Breakwater.
In all, researchers have installed 288 tiles. They will study and compare the textures as well as sizes at different depths in Bay waters.
Three times a year, at low tide, the team climbs over the wall to inspect them. They will gather data on the marine life, as well as the impact the waves, salinity, and tides will have on the colonies.
With some species, they are also measuring metabolic flux. Some are brought back to street level for a closer look.
"What you're seeing is some amazingly luxurious growth of native seaweeds," noted Zabin.
The once-barren tiles are now brimming with native marine life. Zabin pointed a few examples to CBS News Bay Area.
"This is our native Olympia Oyster," she explained, as she pointed to a specimen about the size of a quarter.
Then Zabin showed a sea spider or pycnogonid which was scrambling around the tile, and a bright yellow sea slug covered in spots.
What makes these tiles so different: while some are smooth, others are constructed with bumps, and grooves, with portions that stick out, or ledges that provide shade and hold onto water. One experimental tile also contains a special chemical signature that marine species find attractive.
The cutting-edge experiment is known as the "Living Seawall Project", which was launched in 2022 by SERC with the Port of San Francisco.
The Port is dedicated to defending San Francisco from current and future flood risks as well as earthquake risks and has generated a Waterfront Resilience Program1. This program includes the Living Seawall Pilot project.
The goal is to see whether the textured tiles can better replicate a natural habitat for native species.
"Traditionally when we think of sea walls, these are these flat smooth, vertical surfaces, and there's been this new wave of thinking on how we can retrofit or enhance them to benefit biodiversity," explained Smithsonian scientist Corryn Knapp.
If the textured tiles prove beneficial, they could be incorporated into a new more resilient seawall that's already in the works. In 2018, San Francisco voters approved Prop A, a $425 million bond measure that would start rebuilding the Embarcadero seawall.
"We want to do something that tips the balance in favor of the native species," noted Zabin.
