186 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



more than 90 percent S. nutans which gradually 

 passes into an unhealthy state, particularly in 

 the latter part of the year and in the more north- 

 westerly area. 



LOCAL FEATURES OF THE GULF COAST 

 MARINE ALGAL FLORA ' 



Since the algal vegetation of most of the shore- 

 line of the Gulf of Mexico has not been studied, a 

 review of what has been done is in order and an 

 application of the information derived from this 

 to the rest of the coast. Such an analysis will 

 show what work needs to be done and what areas 

 may be expected to yield the greatest rewards. 



The Florida Keys, as far as we yet know, sup- 

 port much the richest algal flora in our area. 

 About 400 species of marine algae are known from 

 the State, and most of them have been found 

 among the Keys. The fact that intensive study 

 has been limited to the Dry Tortugas was a mat- 

 ter of chance; probably the other more exposed 

 Keys are equally rich. Fortunately, a very help- 

 ful study of the littoral ecology of these islands 

 has recent!}' been presented by the Stephensons 

 (1950) which relates the plant and animal compo- 

 nents. The presence of offshore corals, in itself, 

 is of no present advantage because algae do not 

 grow to any extent on living corals, but the older 

 portions of reefs, dead masses of coral rock and 

 debris form an excellent foundation for algal 

 colonies. Many spectacular ones appear: great 

 beds of Halimeda opuntia and Caulerpas in shallow 

 water, of living browTi and white Padina fans, 

 golden clumps of Dictyotas and iridescent 

 Zonaria zonalis a little deeper. In the next lower 

 depths and in shaded areas, a great variety of 

 "red" algae appear. Beach rock outcrops, the 

 foundation and moat of Fort Jefferson, wide 

 stretches of soft muddy sand, ridges of shell and 

 small coral fragments, all have special advantages 



1 Owing to lack of personal familiarity with most of the Gulf coastline and 

 the fact that published marine botanical studies are generally lacking or 

 poorly documented, the wTiter has appealed for help and information to 

 several persons, many of whom are not botanists, but each is well informed 

 regarding some part of the coast. Among these may be mentioned with 

 especial gratitude: Professor Clair A. Brown, University of Louisiana, 

 Baton Rouge, Dr. P. A. Butler, Fisb and Wildlife Service, Pensacola, Fla., 

 Professor John H. Davis, University of Florida, Gainesville, Dr. Francis 

 Drouet, Chicago Natural History Museum, for the northern shores of the 

 Gulf, Dr. Joel W. Hedgpeth, University of Texas Marine Station, Port 

 Aransas, Roy N. Jervis, University of Michigan, for the Cuban coast. Direc- 

 tor of the Herbarium, Hno. Leon, Colegio de la Salle, Habana. Cuba, Pro- 

 fessor W. Armstrong Price, Agricultural and Mechanical College of Texas, 

 College Station, Dr. Paul Weaver, Houston, Texas, for the Mexican coast, 

 and Professor R. H. Williams, University of Miami, Coral Gables, Fla. 



and are favored by particular species, as discussed 

 elsewhere. The proximity of the Gulf Stream to 

 the east gives good circulation of the water, and 

 at times an abundance of the species of pelagic 

 sargassums is evident. 



Wlien one crosses Florida Bay to Cape Sable 

 one leaves behind the area of most favorable 

 growth conditions, and the floras around the Gulf 

 are thenceforth restricted ones. The west coast 

 of Florida, without the advantage of a strong 

 offshore current and considerably encroached upon 

 by the red mangrove, Rhizophora mangle, offers a 

 less favorable habitat which continues unimproved 

 for many miles to the north since only at isolated 

 spots such as Cape Sable, Pavilion Key, and 

 Marco are large sandy beaches reported and no 

 extensive suitable rocky shore. In the Florida 

 Bay area Davis (1940) reports turtle grass with 

 Acetabularia, Caulerpa, and Gracilaria growing 

 among the pioneer Rhizophora colonies. The 

 mangrove roots may well support the typical 

 Bostrychia vegetation, some suitable mud-favoring 

 species like Penicillus may occur in the shallow 

 open areas, but the vegetation is not likely to be a 

 rich or varied one for neither these inshore fea- 

 tures nor the sand of the offshore islands favor 

 any variety of algae. The Ten Thousand Islands 

 area is especially characterized by the great devel- 

 opment of red mangroves over much shell and 

 marl beneath with beaches showing on the 

 largest islands (Davis 1940). A collection made 

 at Naples shows a poor flora of Enteromorpha, 

 Ectocarpus, Spyridia, and the like. The configu- 

 ration outside Fort Myers and Punta Gorda 

 promises better conditions, but we have no re- 

 ports, and the amount of fresh water discharged 

 may restrict the flora. The Tampa Bay area is 

 certainly different, for rock outcrops, as on Hills- 

 boro Bay, locally offer a good substratum for 

 algal growth. Limited though the collections we 

 have seen have been, they certainly indicate that 

 there is a good, though not very complex, shaUow- 

 water flora of well-developed specimens. How- 

 ever, a good deal of the shoreline is sandy or of 

 shell reefs, with considerable mangrove thickets, 

 and proceeding northward we again come upon an 

 inhospitable, swampy coast. From Cedar Key, 

 we have received coflections indicating a rather 

 limited flora but by no means an extremely re- 

 duced one including several typical tropical 

 genera like Codium, Caulerpa, Padina, Laurencia, 



