calcareous mud, and represents a 

 product of the restricted circula- 

 tion and the numerous sediment 

 producing plants and animals that 

 populate the windward sides of the 

 shoal mud-mounds (Ginsburg and James 

 1974). Referred to as the "Algal 

 Bank Community" by Ginsburg and 

 James (1974), it is made up of loose 

 branched finger corals (Pontes 

 porites and P. divaricata ) and 

 branched and segmented coralline red 

 algae ( Goniolithon strictum ). The 

 shoals surrounding Rodriques Key 

 (off Key Largo) provide the best 

 studied example of this habitat 

 (Turmel and Swanson 1976). 



In addition to the red algae 

 Goniolithon sp., the flora consists 

 primarily of the turtle grass ( Thal- 

 assia testudinum ), laminated blue- 

 green algal biscuits (onocolites) , 

 and numerous green algae, most 

 commonly including Halimeda Opuntia , 

 H. incrassata , and Penicillus capi- 

 tatus . 



The fauna usually includes a 

 variety of siliceous sponges, fora- 

 minifera, tunicates, the stinging 

 coral Millepora alcicornis , several 

 species of brittle stars (ophiu- 

 roids), the sediment-ingesting holo- 

 thurian Holothuria floridana , sever- 

 al echinoids and starfish, and the 

 tunneling shrimp Callianassa sp. 

 The mollusks are esentially the same 

 as described for the grass-covered 

 mud bottom habitat (Turmel and 

 Swanson 1976, Enos 1977, Kissling 

 1977). 



Reef Rubble Habitat 



In the back reef area, immedi- 

 ately adjacent to the outer reefs, 

 and on dead reefs at the slope 

 break, coarse reef rubble accumula- 

 tes and forms a distinctive habitat 

 and associated biotic assemblage. 

 These areas represent an intermedi- 

 ary phase between the mature coral 



reef and hard rock bottom habitat. 

 Biological and physical (hurricanes) 

 forces act on existing coral reefs 

 to provide the substrate for the 

 rubble community. The reef rubble 

 community consists of numerous 

 sediment producing and cementing 

 organisms that will eventually fill 

 and cement the voids and crevasses 

 between the rubble to form a rock 

 bottom (Multer 1977). 



The flora most commonly occur- 

 ring includes the green algae Hali- 

 meda opuntia , Batophora sp., and 

 Dascyladus vermiculata , the red 

 coralline algae Lithothamnium sp., 

 and brown algae (e.g., Sarqassum 

 polyceratum ) . The fauna consists 

 primarily of foraminifera, the fire 

 coral Millipora alcicornis , the 

 starlet coral Siderastrea sidera , 

 numerous alcyonarians (e.g. Plexaura 

 flexuosa , Gorqonia flabellum ) typi- 

 cal of hard rock bottoms and the 

 fore reef habitats, and several 

 echnoids (e.g., Diadema antillarum , 

 Eucidaris tribuloides ) (Enos 1977, 

 Multer 1977). 



The geographic placement of the 

 marine habitats, included in the 

 previous discussion, is a generally 

 accurate picture of the Florida Keys 

 marine setting (Enos 1977). Often, 

 however, this pattern is broken, 

 reflecting localized transient and 

 permanent variations of the physical 

 forces, particularly circulation and 

 depth. Zieman (1982) presents an 

 interesting example of the transient 

 form with a description of seagrass 

 recolonization following a distur- 

 bance known as a blowout. A blowout 

 is an area of seagrass where a dis- 

 ruption of the rhizome/substrate 

 integrity permits the active erosion 

 and undercutting of the seagrass 

 bed. What results is a crescentic 

 form tens of meters wide that pre- 

 sents a gradation of habitat types 

 (bare rock, mud, or sand bottoms to 



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