Invasive Algae Detected Along Kauai's South Shore

The DLNR Division of Aquatic Resources warns of the spread of Avrainvillea erecta, a large green algae that can alter native marine ecosystems.

Apr. 4, 2026 at 10:04am

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The DLNR Division of Aquatic Resources (DAR) has detected the presence of an invasive algae species, Avrainvillea erecta, along the south coast of Kauai. This large green algae, which can form dense meadows and outcompete native species, was first recorded on the island in 2025 and has now been confirmed at several locations. DAR is asking boaters and fishers to help prevent the further spread of this algae by avoiding anchoring in areas where it is known to occur and thoroughly cleaning their equipment after use.

Why it matters

The invasive Avrainvillea erecta algae poses a threat to Kauai's native marine ecosystems by altering the seafloor habitat and potentially outcompeting local species. Its ability to spread through anchoring activity is a particular concern, as it can be easily transported to new locations. Preventing the further spread of this invasive algae is crucial for maintaining the health and biodiversity of Kauai's coastal waters.

The details

Avrainvillea erecta is a large green algae that grows in sandy seafloor habitats at depths of around 60 feet, with observations on Kauai ranging down to 120 feet. In dense patches, it can form thick meadows that trap sediment, alter the sandy environment, and potentially outcompete native species. The algae's distinctive single, fan-like blade extending from a long stalk anchored in the sand makes it easily identifiable. DAR's surveys have confirmed the presence of A. erecta at several locations along Kauai's south coast, with patch densities ranging from sparse to dense, and some areas exceeding 80% cover.

  • In 2025, Avrainvillea erecta was newly recorded on Kauai.
  • In October 2026, DAR's Aquatic Invasive Species team conducted surveys and confirmed the presence of A. erecta at several locations along Kauai's south coast.

The players

DLNR Division of Aquatic Resources (DAR)

The state agency responsible for managing and protecting Hawaii's aquatic resources, including the detection and monitoring of invasive species like Avrainvillea erecta.

Avrainvillea erecta

A large green algae species that has recently been detected in Kauai's coastal waters, posing a threat to native marine ecosystems by forming dense meadows and outcompeting local species.

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What’s next

DAR is asking ocean users, especially boaters and fishers, to help prevent the further spread of Avrainvillea erecta by avoiding anchoring in areas where it is known to occur, particularly in deeper sandy habitats. If anchoring is unavoidable, they recommend thoroughly cleaning and sanitizing anchors and anchor lines before moving to another site.

The takeaway

The detection of the invasive Avrainvillea erecta algae along Kauai's south coast highlights the importance of vigilance and community involvement in monitoring and preventing the spread of non-native species that can disrupt local marine ecosystems. By working together to avoid anchoring in affected areas and properly clean equipment, ocean users can play a crucial role in protecting Kauai's coastal waters.