San Diego Bay Gets $200K Grant to Fight Invasive Caulerpa Algae

The Port of San Diego extends emergency declaration as it works to eradicate the fast-growing algae threatening the bay's marine ecosystems.

Jan. 27, 2026 at 7:47pm

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The Port of San Diego is continuing its emergency response to an invasive algae known as Caulerpa (Caulerpa prolifera) found in San Diego Bay. The Board of Port Commissioners has extended the local emergency declaration through March 15, 2026, marking the 18th continuance since the initial declaration in November 2023. Caulerpa poses a significant threat to the bay's native marine life, including eelgrass, which forms the base of the food chain. Divers have been applying sealed benthic barriers to known patches of the algae, and the Port has been awarded a $200,000 grant to support ongoing survey and eradication efforts.

Why it matters

Caulerpa is a fast-growing alga that can choke out native seaweeds and eelgrass, which are critical to the health of San Diego Bay's marine ecosystem. Eelgrass provides shelter and food for numerous species, including over 70 types of fish and more than 100 endangered green sea turtles. Protecting this habitat is crucial to maintaining the bay's biodiversity and water quality.

The details

The first discovery of Caulerpa in San Diego Bay occurred in September 2023 during a routine dive survey in the Coronado Cays. Since then, approximately 11,300 square feet of the algae has been identified, with over 300 square feet within the Port's jurisdiction. Divers have been applying sealed benthic barriers to known patches, a method that has proven successful in other Southern California locations. The Port is collaborating with the Southern California Caulerpa Action Team, a coalition of agencies working to prevent further spread. Complete eradication requires two years of monitoring with no new discoveries.

  • Caulerpa was first discovered in San Diego Bay in September 2023 during a routine dive survey in the Coronado Cays.
  • The Board of Port Commissioners has extended the local emergency declaration through March 15, 2026, marking the 18th continuance since the initial declaration on November 14, 2023.

The players

Port of San Diego

The government agency responsible for managing and promoting the Port of San Diego, which includes San Diego Bay.

Southern California Caulerpa Action Team

A coalition of agencies working to prevent the further spread of Caulerpa in Southern California.

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What’s next

Complete eradication of Caulerpa in San Diego Bay requires two years of monitoring with no new discoveries.

The takeaway

The fight against the invasive Caulerpa algae in San Diego Bay underscores the critical importance of protecting the bay's delicate marine ecosystem, which is home to a diverse array of species and habitats. The ongoing eradication efforts, supported by a $200,000 grant, demonstrate the commitment of local authorities to safeguarding the bay's ecological balance.