floating debris moves according to 

 the whims of the tide and wind-dri- 

 ven currents. Some are exported 

 seaward into the Florida Current, or 

 westnorthwest through the Keys into 

 the gulf, or washed onshore to be- 

 come part of the sea wrack (Zieman 

 1982). Turtle grass typically 



retains most of its leaf biomass 

 locally, incorporating it as litter 

 and thus recycling its nutrients. 

 Manatee grass, because of its cir- 

 cular shape and relatively smaller 

 diameter is more susceptable to 

 grazing loss; as much as 60% to 100% 

 of the daily production may be de- 

 tached and exported (Zieman 1982). 



In contrast to Florida Bay and 

 the lower Everglades, less detritus 

 is exported from the Florida Keys. 

 Zieman (1982) estimates that only 

 about 5.1% of the daily production 

 of turtle grass ( Thalassia testu- 

 dium ) is exported, and this is 

 primarily as bedload. The rest is 

 incorporated into litter, decompo- 

 sed, or fed upon. This rather tight 

 nutrient cycling and energy flow 

 probably results from a combination 

 of forces: (1) high physical ener- 

 gies leading to high productivity; 

 (2) the stable climate which pro- 

 motes the development of extremely 

 energy efficient communities such as 

 coral reefs; and (3) the location of 

 the Keys as an interface between the 

 nearshore estuaries and pelagic 

 zones. 



Because of high physical energy 

 of mixing. Keys' waters are extreme- 

 ly clear, swept clean as it were by 

 nearby oceanic currents. The gener- 

 al lack of turbid terrestrial runoff 

 also contributes to water clarity as 

 does the vacum cleaner effect of 

 filtering corals and plankton, and 

 the sediment trapping effect of 

 seagrass beds. These conditions 

 promote seagrass and coral reef 

 productivity. 



The coral reef exemplifies the 

 concept of the complex and efficient 

 recycling system in which scleracti- 

 nian coral polyps maintain a symbi- 

 otic relationship with the algal 

 zooxanthellae. The algae are pro- 

 tected in the tissues of the coral 

 animals, which are themselves pro- 

 tected by highly specialized cell 

 products, the nematocysts (stinging 

 organelles used to paralyze and trap 

 prey). Coral respiration and algal 

 photosynthesis result in a mutually 

 beneficial exchange of gases (CO* 

 and O2), nutrients, and organic 

 materials. Certain of the organic 

 materials produced by the zooxan- 

 thellae are used in the development 

 of the corallum structure (Goreau 

 1959, Odum et al. 1974). 



The close recycling of mater- 

 ials at the primary trophic levels 

 emphasizes the role of the mobile 

 resident and transient organisms as 

 sources of energy flow between the 

 keys habitats and between pelagic 

 and nearshore habitats. Faunal 



interactions between keys habitats 

 fall into 3 general, but by no means 

 exclusive, categories: 



(1) mangrove - seagrass interac- 

 tions; 



(2) upland - seawrack - shallow 

 flats interactions; and 



(3) seagrass - coral reef inter- 

 actions. 



Examples of category (1) in- 

 clude the grey snapper ( Lutjannus 

 qriseus ) , spotted seatrout ( Cyno - 

 scion nebulosus ), and the red drum 

 ( Sciaenops ocellota ) which initially 

 recruit into the seagrass habitat, 

 and with growth, move into the man- 

 grove areas for several years (Heald 

 and Odum 1970). 



Examples of category (2) come 

 from both land and water. On land, 

 the raccoon ( Procyon lotor ) is a 

 nocturnal visitor to the shoreline 



200 



