State of Hawai'i
Division of Aquatic Resources
Learn & Explore/Species/Introduced & Invasive/Prickly Seaweed
Category: Invasive
A widespread invasive seaweed that smothers native coral and algae communities
Prickly Seaweed
(Acanthophora spicifera)
Smooth cylindrical branches 4
Can be light pink, brown, green or yellow in color 4
Usually dark in color in intertidal areas and lighter in color in low water motion areas 2
Typically found on small reef flats, in tidepools, and in the intertidal zone of beaches 2
Generally attaches to hard substrates 1
Reproduces asexually through fragmentation, which leads to widespread distribution 2
Often grows next to and competes with native species 1
Most abundant seaweed on shallow reefs, most widespread invasive algae in Hawai‘i 4
Unintentionally introduced from Guam through hull fouling in 1950 4
First fragments were discovered in Pearl Harbor in 1952 4
Kauaʻi: Present
O‘ahu: Present
Molokaʻi: Present
Lānaʻi: Present
Maui: Present
Hawaiʻi Island: Present
Urchin outplanting efforts in Kāne‘ohe Bay and Waikīkī MLCD/FMA
UH Botany Department. (2001). Acanthophora spicifera. Marine Algae of Hawaiʻi. https://www.hawaii.edu/reefalgae/invasive_algae/rhodo/acanthophora_spicifera.htm
Global Invasive Species Database (GISD). (2021). Species profile: Acanthophora spicifera. https://www.iucngisd.org/gisd/species.php?sc=1060 on 22-03-2021.
CABI Invasive Species Compendium. (2019). Acanthophora Spicifera. [Data sheet]. https://www.cabi.org/isc/datasheet/107763
Hawai‘i Ecosystems at Risk Project (HEAR). (2017). Acanthophora spicifera (Rhodomelaceae). https://www.hear.org/species/acanthophora_spicifera/