Invasive Algae          Red Algae            Green Algae             Brown Algae               Seagrasses             Glossary            

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In the 50 years since its introduction,
Acanthophora spicifera has become one of the most successful and abundant algae on Hawaiian reef flats. It often out competes other reef algae, such as species of Laurencia and Hypnea.

Distribution of A. spicifera in Hawaiian Islands.
Map by Jen Smith.

A Pocillipora meandrina surrounded by A. spicifera.

Apices are pyramidal, with incurved trichoblasts. Peri-central cells corticated densely, central axial cells usually evident. In older axes, central axial filaments may be surrounded by small-celled adventitious filaments.

Hawai‘i:  Well established on Maui, Moloka‘i, Lana‘i, Kaho‘olawe, O‘ahu, and Kaua‘i. Recently identified on Hawai‘i Island.

Mechanism of Introduction:  Unintentional introduction from Guam.

Worldwide:  Acanthophora spicifera has a nearly continuous distribution in all the tropical and subtropical seas of the world.

Acanthophora spicifera is the most widespread and successful alien alga in Hawai‘i. It appeared for the first time in Hawai‘i in the early 1950’s, most likely entering on a barge from Guam. The red alga is found on reefs and intertidal habitats. This alga’s plastic morphology has allowed it to adapt to different conditions and invade a diversity of habitats. The brittle nature of the branches often results in fragmentation, which contributes to frequent, large free-floating populations and widespread distribution.

A. spicifera benefits from association with aggregates of other algal species that are more tolerant of wave exposure and are able to retain water when exposed to air. It is often found growing next to and competing with the native species of Laurencia and Hypnea cervicornis. H. cervicornis may even entangle in the upper branches of A. spicifera as an epiphyte.