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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
Erect plants, to 40 cm
tall, with solid cylindrical branches, 2 - 3 mm wide, branched either
sparingly to repeatedly. Main branches have short, determinate branches,
irregularly shaped and spinose, with spines numerous and radially
arranged. There are no spines on main axes. The plant grows from a
large, irregularly shaped holdfast.
high-motion water areas, Acanthophora spicifera has short (4 - 10
cm), compact and very dense thalli. In moderate or low water motion
areas, the thalli are tall (10 - 25 cm), more openly branched and occur
in scattered clumps. Color is highly variable: can be
shades of red, purple, yellow, orange, or brown. Are often very dark in
color in intertidal, high motion areas. Usually lighter color in shallow
areas with low water motion and reflective sandy or silty bottoms.
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
Acanthophora spicifera is abundant on calm, shallow
reef flats, tidepools, and on rocky intertidal benches. This alga
usually attaches to hard substrates, such as rocks, basalt ledges, or
dead coral heads. It may also
be found free-floating, due to its brittle, easily-broken nature.
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.
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.
1999. Marine Red Algae of the Hawaiian Islands. Bishop Museum Press,
1961. A possible invader of the marine flora of Hawai‘i. Pacific Science
and J.L. McLachlan, 1986. Ecological studies of the alga, Acanthophora
spicifera (Vahl) Bøerg. (Ceramiales: Rhodophyta): Vegetative
fragmentation. J. Exp. Mar. Biol. Ecol., 104: 1-21.
and J.L. McLachlan, 1988. Composition, export, and import of drift
vegetation on a tropical, plant-dominated, fringing-reef platform
(Caribbean Panama). Coral Reefs, 7: 93-103.
and Mark M., 2000. Caribbean Reef Plants. OffShore Graphics, Washington,
and J. Hunt, 1979. Seaweeds of Hawai‘i. Oriental Publ. Co., Honolulu,
1992. The ecological invasion of Hawaiian reefs by two marine red algae,
Acanthophora spicifera (Vahl) Bøerg. and Hypnea musciformis
(Wulfen) J.Ag., and their association with two native species,
Laurencia nidifica and Hypnea cervicornis J.Ag. ICES Mar. Sci.
Symp., 194: 110-125.
J. and G. H. Balazs. 2000. Identification manual for dietary vegetation of
the Hawaiian green turtle, Chelonia mydas. NOAA TM-NMFS-SWFSC-294.
Ecological Success of Alien/Invasive Algae in Hawai‘i:
Marine Invasives in Hawai‘i: