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FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Halophila baillonis Aschers. antl H. engeimannii 

 Aschers. of the Hydrocharitaceae. Halophila 

 aschersonii Ostenf., as well as the above, is found 

 in the Caribbean and is reported as far south as 

 Recife, Brazil. The widespread Ruppia maritima 

 L., widgeongrass of the Potamogetinaceae and 

 Zannichellia palustris L., horned-pondweed of 

 the Zanichelliaceae, though usually not marine, 

 are found in brackish waters along the Gulf coasts. 



Only two other genera of marine flowering plants 

 are reported from the New World. Zostera marina 

 L., eelgrass of the Zosteraceae is found in shallow, 

 quiet waters of the Pacific and Atlantic coasts of 

 North America, reaching as far south along the 

 latter as North Carolina. Other species of this 

 genus have been collected on the coasts of Chili 

 and Uruguay (Setchell, 19.34b, 1935). Phyl- 

 lospadir scouleri Hook, and P. torreyi Wats., also 

 of the Zosteraceae, grow along the Pacific coast 

 near low-tide mark where they are exposed to 

 strong wave action. 



The Gulf and Caribbean sea-grasses are limited 

 in habitat largely to soft marl, mud, or sand in 

 warm, clear, shallow marine water. Thalassia, 

 Diplanthera, and Syringodium form extensive sub- 

 marine meadows or beds in shallow water of bays 

 and lagoons, seldom being exposed except at the 

 lowest tides. These plants extend also into deeper 

 water, having been dredged in the Dry Tortugas 

 area to 11 meters (Taylor 1928). Generally, the 

 species of Halophila thrive on calcareous bottoms 

 in much deeper water. H. baillonis has been 

 dredged from 5.5 to 29.3 meters but more com- 

 monly in 14 to 18 meters and H. engeimannii in 

 still deeper water, 4.6 to 73.2 meters and one 

 estimated depth of 91 meters (Taylor 1928). H. 

 aschersonii was dredged with H. baillonis along 

 the south shore of Puerto Rico from a depth of 18 

 meters (Howe 1915). These marine plants are 

 usually associated in southern Florida waters 

 with such marine algae as Acetabulum, Caulerpa, 

 Gracilaria, Halimeda, Hypnea, Penicillus, Poly- 

 siphonia, Sargassum, and Udotea. Thalassia espe- 

 cially furnishes a good habitat for such algal 

 epiphytes as Melohesia farinosa Lamouroux. 

 Ruppia is often abundant in shallow water of 

 enclosed bays, tidal estuaries, or other areas 

 where the water is less saline. 



The distribution of sea-grasses in the Gulf is 

 poorly known. All five Gulf species grow along 

 the northwestern coast of Cuba and around the 



Florida Keys. All of these but H. baillonis have 

 been collected in the Tampa Bay region by the 

 writer and on the northern Gulf coast of Florida 

 by others. Thalassia, Diplanthera, and Halophila 

 engelmanii are present in the coastal waters of 

 southern Texas. Several of the species must occur 

 along the Mexican coast. The apparent rarity of 

 marine spermatophytes except Ruppia on the 

 northern Gulf coast between Bay County, Florida, 

 and Aransas County, Texas, may be significant. 

 Perhaps the silt and fresh water dumped into the 

 Gulf by the Mississippi and other large rivers are 

 involved. 



Outside the Gulf and Caribbean, Diplanthera 

 has been collected on the coast of North Carolina 

 and Diplanthera, Thalassia, Syringodium., and H. 

 baillonis on Bermuda shores. Two species, Tha- 

 lassia testudinum. and Diplanthera wrightii have 

 been collected on both the Caribbean and Pacific 

 coasts of the Isthmus of Panama, possibly indi- 

 cating a former water connection across the isth- 

 mus. Close relatives of species in each of the 

 four Gulf genera are found in the Indo-Pacific 

 region. In all, approximately 40 species of sea 

 grasses are known, and the largest concentrations 

 of these occur in tropical waters of the Indian 

 Ocean, western Pacific Ocean, and the Red Sea. 



MANGROVE SWAMP 



Most conspicuous of the plant communities of 

 the Gulf coast is mangrove swamp. There is 

 much literature about this swamp-forest or swamp- 

 thicket that is so characteristic of tropical coasts 

 around the world. Davis (1940) has made a 

 thorough study of mangroves in Florida with 

 emphasis on their ecology and geologic role. 

 Their importance as land-biulders in Florida has 

 been emphasized, perhaps overemphasized, by 

 several writers (Curtiss 1888; Sargent 1893; Pol- 

 lard 1902; PhiUips 1903; Vaughan 1910; Harsh- 

 berger 1914; Simpson 1920). The embryology of 

 Rhizophora mangle L. has been studied by Cook 

 (1907), the physiology by Bowman (1917), and 

 the dispersal and establishment by Egler (1948). 

 Dispersal of Rhizophora and other mangroves has 

 been considered in some detail by Crossland 

 (1903), Guppy (1906, 1917), Ridley (1930), and 

 other biologists. In addition to some of the above 

 papers good accounts of mangrove swamp on 

 Gulf coasts have been written by Harper (1927) 

 and Davis (1942, 1943). Publications describing 



