Invasive Algae – Caulerpa prolifera

Caulerpa prolifera found in Newport Bay
Caulerpa prolifera


In March, 2021, an invasive algae species was discovered in Newport Bay, California. The algae, which is native to Florida and other subtropical and tropical locales, is scientifically known as Caulerpa prolifera. It can grow quickly, choking out native seaweeds and potentially harming marine life through lost habitat.

Federal, state, and local agencies immediately joined forces to identify the extent of the algae's infestation in Newport Bay. California Department of Fish and Wildlife (CDFW) scientists and divers were deployed in April and May, 2021 to map and confirm the location of the infestation.

Why is Caulerpa Bad?

The invasive algae can grow quickly and rapidly out-compete native species, including native eelgrass, and may be inedible to native marine herbivorous fish and invertebrates. The species has invaded seagrass and soft‐bottom habitats in the Suez Canal, the Canary Islands, and Portugal, dramatically displacing native algae, plants, and animals.

Based on environmental impacts of other Caulerpa species, Caulerpa prolifera is potentially a serious invasive. Other species of Caulerpa are well‐documented as having aggressively displaced native habitats when introduced, both in California, Australia, and Mediterranean waters. Allowing any species of Caulerpa to become established and spread within California is likely to result in considerable economic, recreational, and biological impacts.

In 2000, a close relative, Caulerpa taxifolia was found in two southern California lagoons. The seriousness and acknowledged threat prompted an effective, highly successful eradication project. This eradication took six years at a cost of more than seven million dollars. The successful eradication, however, led to the recovery of critically important eelgrass habitat, and protected California’s coastal ecosystems. Risk modeling for Caulerpa conducted in 2006 placed China Cove in the highest risk category for an introduction.

Caulerpa Eradication Plan

Based on diver surveys, the infestation appears to be presently contained within a small area of Newport harbor at China Cove. The scientific consensus is that it is critical to take immediate action to eradicate the species. Due to the high level of recreational activities in the area, and Caulerpa’s ability to spread through fragmentation, initial removal efforts will begin as soon as possible.

CDFW, along with partners on the Southern California Caulerpa Action Team from the Santa Ana Regional Water Quality Control Board, State Water Resources Control Board, California Coastal Commission, NOAA’s National Marine Fisheries Service, U.S. Fish and Wildlife Service, and the City of Newport Beach have created the Newport Bay Rapid Response Eradication Plan (PDF), to address the immediate need to remove the invasive algae Caulerpa prolifera from China Cove. This plan includes the following components:

  • Initial Containment –To help prevent disturbance by boat anchors, boat wakes, divers, or swimmers, the identified infestation area has been isolated by the City of Newport Beach through placement of floating buoys and lines surrounding the area.
  • Localized Eradication Level Survey - Prior to removal, an intensive diver survey will be conducted within the China Cove infestation area. Divers will locate, identify, and mark any Caulerpa found.
  • Localized Removal - Diver-assisted suction removal will be used to completely remove Caulerpa prolifera, including sub-surface portions. The removed material will be pumped to the beach for separation of algae and solids from the water. The discharge will be handled with great caution to prevent re‐introduction to the nearshore environment.
  • Post Removal Surveys – Diver surveys will be conducted both immediately following removal and over a longer time frame to help ensure the species is completely removed and does not repopulate the area.
  • Broad Area Surveys – Diver surveys will occur in surrounding areas, both inside and outside Newport Harbor, to ensure other areas have not been invaded.

Species Identification

Caulerpa prolifera is a species of green algae in the family Caulerpaceae. The algae is bright green and consists of a number of blades linked by underground runners (stolons), which attach to the substrate with small root-like structures (rhizoids). Below are photos of Caulerpa prolifera found in Newport Bay.

Caulerpa prolifera found in Newport Bay - link opens in new window
Caulerpa prolifera found in Newport Bay - link opens in new window
Caulerpa prolifera found in Newport Bay - link opens in new window
Caulerpa prolifera found in Newport Bay - link opens in new window

What Should You Do?

Although there is significant concern this species could potentially be harmful to native species, there is no danger to humans. However, it is imperative that the public avoid contact with the plant due to its extreme ease of recolonizing from just tiny fragments. If you believe you have seen this invasive algae, please use the form on the right to submit a notification to CDFW.

Additional Information

Suspect Invasive Species Sighting Report


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