Aquatic Invasive Species

Prickly Seaweed (Acanthophora spicifera)

Description:

• Smooth cylindrical branches (CABI, 2019)
• Can be light pink, brown, green or yellow in color (CABI, 2019)
• Usually dark in color in intertidal areas and lighter in color in low water motion areas (GISD, 2021)

Habitat:

• Typically found on small reef flats, in tidepools, and in the intertidal zone of benches (GISD, 2021)
• Generally attaches to hard substrates (UH Botany Dept., 2001)

Impacts & Concern:

• Reproduces asexually through fragmentation, which leads to widespread distribution (UH Botany Dept., 2001)
• Often grows next to and competes with native species (UH Botany Dept., 2001) 
• Most abundant seaweed on shallow reefs, most widespread invasive algae in Hawai‘i (HEAR, 2017)

Introduction:

• Unintentionally introduced from Guam through hull fouling in 1950 (HEAR, 2017)
• First fragments were discovered in Pearl Harbor in 1952 (HEAR, 2017)

Distribution in Hawaii (UH Botany Dept., 2001): 

• Kauai: Present 
• O‘ahu: Present
• Molokai: Present
• Lanai: Present
• Maui: Present
• Big Island: Present

Related AIS Team Management Projects:

• Urchin outplanting efforts in Kāne‘ohe Bay and Waikiki MLCD/FMA

References:

• UH Botany Department (2001). Acanthophora spicifera. Retrieved March 22, 2021, from https://www.hawaii.edu/reefalgae/invasive_algae/rhodo/acanthophora_spicifera.htm
• Global Invasive Species Database (GISD) (2021) Species profile: Acanthophora spicifera. Retrieved March 22, 2021, from http://www.iucngisd.org/gisd/species.php?sc=1060 on 22-03-2021.
• CABI Invasive Species Compendium (2019). Acanthophora Spicifera Datasheet. Retrieved March 22, 2021, from https://www.cabi.org/isc/datasheet/107763
• Hawaii Ecosystems at Risk Project (HEAR) (2017). Acanthophora spicifera (Rhodomelaceae) – Hear species info. Retrieved March 22, 2021, from http://www.hear.org/species/acanthophora_spicifera/