Acanthophora spicifera is a species of marine red algae

Red algae

The red algae are one of the oldest groups of eukaryotic algae, and also one of the largest, with about 5,000–6,000 species  of mostly multicellular, marine algae, including many notable seaweeds...

 in the family Rhodomelaceae

Rhodomelaceae

Rhodomelaceae is estimated to be the largest red algae family, with about 125 genera and over 700 species....

.

Distribution

Distribution of Acanthophora spicifera include:

• Guam
  Guam
  Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
  
  
• Houtman Abrolhos
• Hawaii
  Hawaii
  Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...
  
   - non-indigenous. It was unintentionally introduced to Pearl Harbor, Hawai‘i from Guam
  Guam
  Guam is an organized, unincorporated territory of the United States located in the western Pacific Ocean. It is one of five U.S. territories with an established civilian government. Guam is listed as one of 16 Non-Self-Governing Territories by the Special Committee on Decolonization of the United...
  
   in 1950 and has since become the most common nonindigenous algal species in the main Hawaiian Islands. On the west coast of Hawai‘i Island it has been documented at three sites, including Kaloko Fishpond in Kaloko-Honokohau National Historical Park
  Kaloko-Honokohau National Historical Park
  Kaloko-Honokōhau National Historical Park is a United States National Historical Park located in the Kona District on the Big island of Hawaii in the U.S. state of Hawaii. It includes the National Historic Landmarked archaeological site known as the Honokōhau Settlement...
  
  , Pu'ukohola Heiau National Historic Site and Pu'uhonua o Honaunau National Historical Park
  Pu'uhonua o Honaunau National Historical Park
  Puuhonua o Hōnaunau National Historical Park is a United States National Historical Park located on the west coast of the island of Hawaii in the U.S. state of Hawaii. The historical park preserves the site where, up until the early 19th century, Hawaiians who broke a kapu could avoid certain...
  
  .

Ecology

Acanthophora spicifera is one of the most common nonindigenous algal species in Hawaii and it displaces

Interspecific competition

Interspecific competition, in ecology, is a form of competition in which individuals of different species compete for the same resource in an ecosystem...

 many native species where it is abundant.

The success of Acanthophora spicifera in invading benthic habitats is attributed to: (1) its ability to reproduce both sexually and vegetatively (by fragmentation); (2) successful epiphytism; and (3) its adaptability to a wide range of hydrological conditions. Rapid recolonization is probably due to the ability of Acanthophora spicifera to regrow from even small amounts of residual tissue and the high rate of reproduction.

Algal abundance is influenced by both nutrient

Nutrient

A nutrient is a chemical that an organism needs to live and grow or a substance used in an organism's metabolism which must be taken in from its environment. They are used to build and repair tissues, regulate body processes and are converted to and used as energy...

 availability and herbivory. The combination of high nutrient concentration and low herbivory, as in Kaloko Fishpond, promotes greater increases in algal abundance than an increase in nutrients alone. Herbivory, therefore, appears to play an important role in preventing tropical macroalgal growth.

Acanthophora spicifera is a palatable and highly preferred food for herbivorous fishes in Hawai‘i and has been found in the mouths of green sea turtle

Green Sea Turtle

The Green sea turtle or green turtle is a large sea turtle of the family Cheloniidae. It is the only species in the genus Chelonia. Its range extends throughout tropical and subtropical seas around the world, with two distinct populations in the Atlantic and Pacific Oceans...

s.

Attempt to control

Acanthophora spicifera is a very difficult alga to eradicate, but controlling its spread and density may be feasible. A a range of approaches was assessed to control this invasive alga in Kaloko Fishpond in Hawaii. Removal techniques were labor intensive and had limited effect. All experiments showed a substantial initial decrease in algal density, but the long-term effect was minimal because of rapid regrowth. The most promising removal method was the use of submerged shelters to raise local densities of herbivorous fishes. Fishes grazed the alga and quickly reduced the biomass

Biomass

Biomass, as a renewable energy source, is biological material from living, or recently living organisms. As an energy source, biomass can either be used directly, or converted into other energy products such as biofuel....

. However, the large number of predators and absence of topographical structure will make it challenging to provide sufficient
shelters to increase the herbivorous fish population (biocontrol

BioControl

BioControl is a peer-reviewed scientific journal published by Springer Science+Business Media covering all aspects of basic and applied research in biological control of invertebrate, vertebrate, and weed pests, and plant diseases. The journal was established in 1956 as Entomophaga and published by...

) in the entire fishpond.