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Hypnea musciformis (Wulfen) J.V.Lamour. |
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Description: Plants often in clumps or masses 10-20 (50) cm high of loosely intertwined cylindrical axes and branches becoming progressively slenderer distally, infrequently coarser; axes 0.5-1.0(2) mm diam. Below, tapering to apices; branching irregular and variable, with broadened hook (hamate), or tendril-like, often twisted around axes of other algae; branches with small spinelike branchlets 50-200um at base, also tapered, simple or bifurcate and more or less numerous on older or younger (basal or upper) parts of same plant; primary holdfast lacking or difficult to recognize, tangled with other larger algae. Tetrasporangial sori on branchlets as for genus Spermatangial plants not detected. Cystocarps globular, usually crowded toward upper parts. Introduction and Origin: The introduction of H. musciformis occurred in Kaneohe bay, during January 1974. H. musciformis was a stowaway on other algae that was used for an agar substitute. It was originally from Florida, this species being found throughout the Caribbean. Since its arrival in Hawaii, H. musciformis was used as an agar source but commercial growth proved non-profitable. Hawaiian Distribution: Oahu, Molokai, and Maui. Spermatangial plants not detected. H. musicformis became abundant on Kaneohe reefs in three years. In the following two years H musciformis had spread to Waimanalo and Kaaawa. H. musciformis spreads at a rate of 3.8km a year Habitat: Low intertidal and shallow subtidal reef flats, frequently entangled on Sargassum. Epiphytic on various other algae, or directly attached to sandy flat rocks. Environmental Effects: H. musciformis forms dense floating masses that block out the sunlight, and eventually wash up on the beach. It outcompetes Hypnea cervicornis for substrate and is currently the most dominant epiphytic algae. World Distribution: Type locality: Trieste, Italy. Mediterranean, Indian Ocean, the Philippines in the Atlantic from the Caribbean to Uruguay. Commercial Interests: H. musciformis was brought in as a potential source for kappa carrageenan in Hawaii, turning out not to be cost effective. Due to its brittleness, fragments clogged many of the filters and nets. Because of its high abundance on the shores of Maui, H. musciformis could be used as soil fertilizer. Rate of Spread / Method: Growth rate is almost fifty percent of body mass per day (Dawes). Factors likely to influence Spread and Distribution: The lack of tertiary sewage treatment plants in Maui have changed coastal waters conditions from oligotrophic to eutrophic. When hurricane Iniki hit Hawaii the abundance of H. musciformis decreased abruptly, yet it recovered immediately. This shows that land-based nutrient outputs are very high. Reasons for Success: High growth rate. Thallus with multiple meristems ensures fast vegetative reproduction. Abundant production of tetraspores. Hook-like tips of branches are a morphological advantage, facilitating epiphytic growth. Control Methods: Biological control could be possible, since there are many organisms that feed on H. musciformis. It has been documented that grazing by Gammaridea (amphipods) and Aplysia (seahares) affect its distribution. Gut analysis of turtles revealed large amounts of H. musciformis in their diet. Also, invertebrates are known to live within the large clumps of H. musciformis. However, grazing is of little effect due to the high growth rate of this algae. A possible means of control should be to explore its suitability for human consumption. References: http://www.fao.org/docrep/xO169f/xO169fl6.htm http://www.dana.ucc.nau.edu/~ks24/hypnea.html Brchez, F. R, Pereira. Et al. 1993. Culture of Hypnea musciformis(Rhodophyta, Gigartinales) on artificial substrates attached to linear ropes. Hydrobiologia. 261:415-420. Durako, M. Dawes, C. 1980. A compariative Seasonal Study of Two Populations of Hypnea musciformis from the East and West Coasts of Florida, USA I. Growth and Chemistry. Marine Biology. 59:151-156. Durako, M. Dawes, C. 1980. A compariative Seasonal Study of Two Populations of Hypnea musciformis from the East and West Coasts of Florida, USA II. Growth and Chemistry. Marine Biology. 59:157-162. Mshigeni, K. W, Lorri. 1977. Spore Germination and Early Stages of Development in Hypnea musciformis(Rhodophyta, Gigartinales). Marine Biology. 42:161-164. Russel, D. 1992. The ecological invasion of Hawaiian reefs by two marine red algae, Acanthophora spicifera and Hypnea musciformis and their association with two native species, Laurencia nidifica J.Ag. and Hypnea cervicornis J. Ag. ICES mar. Sci. Symp. 194:110-125. Schenkman, R.1989. Hypnea musciformis(Rhodophyta) Ecological influence on Growth. Journal of Phycology. 25:192-196. Yogamoorthi, A. 1998. Ecological studies on phytal fauna associated with intertidal seaweeds from south east coast of India. Journal of Ecobiology. !0:245-250. |
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