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Invasive Algae Home Red Algae Green Algae Brown Algae Seagrasses Glossary |
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Click on pictures for larger images
Halophila decipiens, a pantropical species, was recently discovered in both shallow and deep sandy areas on Hawaiian coasts. It may compete with the native seagrass.
Flower on Halophila decipiens.
Halophila decipiens bed, O‘ahu.
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Description Pairs of leaves on petioles formed along a rhizome rooted in sand. Leaves from 3 - 8 mm wide, obovate, not narrowing at base, thin and hairy; margin spinulose. Petiole 3 - 15 mm long. Male and female flowers are produced at each leaf node. Branching leads to intertwined plants in a meadow or runners colonizing new substrate.
Structural Features Leaf blade thin and flaccid out of water; fine hairs on both sides of leaf make leaf feel rough. Spines on margin visible with magnification. Ripening fruit often conspicuous on rhizome.
Habitat Forms dense meadows in sand rich in organic matter. Found at depths from 0.5 - 35 m. Often coated with epiphytes.
Distribution Hawai‘i: O‘ahu, Hawai‘i. Mechanism of Introduction: Unknown. Worldwide: Subtropical to tropical Pacific, Indian, Atlantic Ocean, Caribbean.
Ecology/Impact Halophila decipiens was discovered October, 2000 near the Kahala Mandarin Hotel and several additional populations have since been located. If it is found to out-compete the native Halophila hawaiiana, then it may pose a threat to that species due to its great reproductive capacity. Research is underway to determine what impact this species may have on the native seagrass and associated communities. |
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References Phillips, R.C. and E.G. Menez. Seagrasses. 1988. Smithsonian Contributions to the Marine Sciences 34. 89 pp. E.G. Menez and R.C. Phillips. 1983. Seagrasses from the Phillipines. Smithsonian Contributions to the Marine Sciences 21. 40 pp.
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Web Pages Seagrass Page. http://www.botany.hawaii.edu/seagrass/
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