Three football fields' worth of specially textured concrete is about to line parts of San Diego Bay, designed not just to hold back waves but to create habitat in nooks shaped like natural tide pools. The Port of San Diego is installing 1,060 linear feet of this habitat-focused shoreline armor at two bay locations after years of testing showed it dramatically out-performed ordinary rock riprap at supporting marine life.
The material, called ECOncrete COASTALOCK, is built to do double duty: stabilizing the shoreline while creating habitat that mimics natural tide pools, according to the Port of San Diego. In a two-year pilot project that launched in 2020, the units doubled species richness and abundance, increased native biodiversity, and produced twice the biomass compared to conventional shoreline armoring, the port reports. 10News also reported on the project, which the port has described as a success.
How the Pilot Took Shape
The roots of the project trace back to 2019, when the port approved an ECOncrete pilot under its Blue Economy Incubator Program specifically to enhance the ecology of riprap armor protecting Harbor Island, according to the port's industry trade publication coverage in Civil Engineering Source. ECOncrete completed the first COASTALOCK installation along Harbor Island in March 2021, placing 74 units across two 75-foot sections of shoreline. The port and ECOncrete then monitored the installation for two years to evaluate how well it held up structurally and ecologically, the trade publication notes.
That monitoring turned up measurable differences from the rock it replaced. Researchers found increasing trends of species richness on the COASTALOCK units compared with the adjacent riprap stone, and significantly higher biomass accumulation, including both organic and inorganic matter, per the same report. The Port and ECOncrete monitored the installation for two years, with measurable gains in species richness and biomass compared with adjacent riprap.
A Second Pilot Waits on Permits
The port isn't stopping with ECOncrete. The Board of Port Commissioners has approved a separate Blue Economy Incubator pilot with a company called Ocean Ecostructures, which has the potential to increase biodiversity in San Diego Bay, the port announced. Ocean Ecostructures plans to install 30 specially designed units on existing infrastructure around the bay, aiming to support continued marine-life growth without adding new shoreline structures.
“The project will explore ways to do more for San Diego Bay using infrastructure already there,” Zach Birmingham said, according to 10News's reporting on the plan. The Ocean Ecostructures project still requires the permitting process to be completed before any units go into the water, and once that happens, the sites will be monitored for two years to assess how the technology performs, 10News reported. Separately, the two-year pilot will be deployed across multiple locations throughout San Diego Bay and monitored for effectiveness, with the explicit aim of enhancing biodiversity at port infrastructure without disrupting daily operations, according to Container News.
Why So Much of the Bay Is Hardened
The push for habitat-friendly concrete reflects how little of San Diego Bay's shoreline remains in a natural state. Concrete is the main construction material for coastal and marine infrastructure worldwide, accounting for more than 70% of ports, coastal defenses and waterfronts, according to the BBC. Roughly 80% of existing shorelines around San Diego Bay are armored and hardened, per a low-confidence figure cited in a California water board document, though that estimate has not been independently confirmed.
Not every expert agrees on how well eco-friendly concrete performs everywhere it's tried. The BBC notes that evidence for eco-friendly concrete as a better surface for marine organisms is very mixed and can depend heavily on location, a caveat worth keeping in mind as San Diego's results get compared elsewhere. The Port of San Diego has backed 15 such pilot projects overall as part of its broader blue-economy efforts.
Other Ports Are Watching Too
San Diego isn't alone in testing textured concrete as a marine habitat tool. The European Living Ports project implemented ECOncrete solutions at the Port of Vigo in Spain, one of the world's largest fishing ports, and reported increased abundance and diversity of fish, invertebrates and algae there, according to CORDIS, the European Commission's research portal. That project also uses low-carbon concrete mixes that can cut the material's carbon footprint by up to 70%. ECOncrete itself was founded in 2012 by two marine biologists aiming to build eco-friendly materials for coastal infrastructure, per the same report.
Similar experiments have popped up from Hong Kong to San Francisco. A preliminary Hong Kong test found eco-tiles doubled the number of marine species compared with bare artificial seawalls, reaching 12 species, the BBC reported. In San Francisco, preliminary findings from the city port's Living Seawall pilot showed native oysters, crabs, seaweed and other marine life colonizing specially designed seawall tiles, according to the San Francisco Port Authority, though that result is also described as preliminary rather than conclusive.
