According te these authors: 



"Carnivorous fishes (e.g. grunts, Pomadasyidae) resting on 

 coral reefs by day and feeding on seagrass invertebrates by 

 night are largely responsible for the enhanced fish biomass 

 characteristic of coral reefs near seagrass beds. The proximity 

 of seagrass beds to coral reefs provides food for fishes and 

 invertebrates feeding within the beds, shelter for juveniles, 

 and organic material exported to reefs. The primary limit to 

 further exploitation is lack of shelter within the beds." 



Thus the patch reef community represents a distinct natural system 

 whose biota is adapted to the environmental conditions of the back reef 

 zone. Continued survival of this system is critical for maintenance of the 

 habitat utilized by numerous fishes and the spiny lobster. Utilization of 

 the patch reefs for shelter from predators allows both juveniles and adults 

 to exploit an enormous and nearby source of energy, the biomass of the seagrass 

 association. Much of this energy, in the form of finfish and shellfish 

 biomass is harvested by both the commercial and sport fishing industry of 

 the Florida Keys. 



b. Reef Flat 



The Looe Key Reef Flat is roughly in the shape of an isosceles triangle, 

 its base facing south towards the Straits of Florida and the apex pointing land- 

 ward to the north. On this landward side there is a very gradual transition 

 from the seagrass association of the Patch Reef area into the Reef Flat, marked 

 mainly by the beginning of extensive sand flats and an elevation of the bottom 

 to about 2 m in depth. From here toward the south, the Reef Flat becomes 

 gradually shallower with the main part of the area showing a depth of approx- 

 mately 1.5 m. The Reef Flat terminates in a sharply defined rock and rubble 

 zone immediately behind the uppermost rim of the Fore Reef. The water depth 

 in this area is no greater that about 0.5 m. The Reef Flat does not show 

 any profile other than the elevation of seagrass ridges approximately 0.5 m 

 above the sand bottom. The benthos consists primarily of calcareous sand, 

 rubble, coarse sediment and extensive seagrass beds. The latter are vegetated 

 by pure stands of turtle grass, or a mixture of turtle grass, manatee grass, 

 and algae. In some areas without seagrass, the bottom community consists of 

 algae and invertebrates. 



The algae, in most area of the Reef Flat, include: species of the genera 

 Halimeda , Udotea , Penicillus , Caulerpa , Rhipocephalus , Cladophoropsis , Dasycladus 

 vermicularis , and several other chlorophycean algae, as well as representatives 

 of the red algal genera Laurencia , Goniolithon , Spyridia , and Chondria . Older 

 blades of turtle grass are almost invariably covered with the red algal 

 epiphyte Melobesia membranacea , and much of the manatee grass was observed 

 to be densely covered with an epiphytic species of Ceramium . Brown algae 

 are represented by species of the genus Dictyota , as well as Padina sanctae-crucis , 

 and Stypopodium zonal e . In the rock and rubble sector of the Reef Flat 

 behind the Fore Reef the algal community consists of those species requiring 

 a hard substrate. These include: Goniolithon spp . , Lithothamnium incertum , 

 large clumps of Halimeda opuntia , Dictyotota spp . , Stypopodium zonaTel 



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