of the stony corals as well as under and behind rubble. They become quite 

 obvious at night when they expose their arms to feed. At least one species, 

 on Looe Key is bioluminescent and displays pulsating light patterns when 

 disturbed. 



The dominant vegetation on the Fore Reef are encrusting species of red 

 algae of the genera Goniolithon , Lithothamnium , and Peyssonellia . Widely 

 scattered small clumps of Halimeda opuntia f. minor . Bryopsis pennata , and 

 Dictyota spp . occur on the tops and sides of the spurs. The distinct paucity 

 of the algal flora found here is probably a reflection of grazing pressure 

 from organisms such as sea urchins. 



The Fore Reef zone has by far the greatest numbers of fish. Almost all 

 of the species encountered in the reef system can be found here, with the 

 exception of some deeper water species only observed beyond a depth of 10 m. 

 Two of the most abundant species, found in the Fore Reef zone, are tomate 

 grunts, ( Haemulon aurolineatum ), and yel lowtail snappers, ( Ocyrus chrysurus ). 

 Absent or rarely seen, according to the Inventory, (Antonius et al 19/8) 

 were grey or mangrove snapper, ( Lutjanus griseus) , and larger serranids, 

 such as black, red and nassau groupers. Black grouper and mangrove snapper, 

 where seen, were usually on the western end of the reef and moving away, out 

 of the range of visibility. 



d. Deep Reef 



At the seaward edge of the spur and groove system a sandflat begins in 

 about 9-11 m depth, wery gradually sloping down with a slight incline. In 

 front of the eastern half of the Fore Reef this sandflat is uninterrupted. 

 At the western half it is intersected by a deep reef, which begins here as a 

 finger-like extension of scattered coral outcrops just beyond the terminus 

 of the spur and groove system. From here a reef flat of 10-12 m depth stretches 

 several hundred meters to the west without showing much profile, representing 

 a comparatively shallow subzone of the Deep Reef. 



Towards the south, the Deep Reef gradually changes into a second subzone. 

 Here, the reef flat curves into a slope of increasing steepness with a consi- 

 derable profile caused by surge channels. In the deepest portion of this 

 subzone, the slope forms a small but true drop-off which ends on a sandflat 

 in about 30 to 35 m depths. In this deepest sector of the Deep Reef, the 

 sediments are quite fine and silt-like and are easily raised up from the 

 bottom. 



The shallower, plateau-like part of the Deep Reef is somewhat similar 

 to the previously described Patch Reefs. Octocorals are dominant here, with 

 a very similar species composition to that of the Patch Reefs, but they do 

 not outnumber stony corals here as much as they do in the Patch Reefs. The 

 most frequently encountered octocoral on this part of the Deep Reef is the 

 plexaurid Muriceopsis petila . Sponges are fairly common and grow to larger 

 sizes than in the Patch Reefs. Stony corals do not exceed medium sizes and 

 are scattered in distribution. 



55 



