10 feet. 



In the Bahamas, localized areas of luxuriant marine growth 

 (corals, algae, sea fans, etc.) are called "heads." This term 

 will be applied to describe such features here. 



The lagoon is 1500 yards wide and transition from lagoon to reef 

 is abrupt and marked by a sharp decrease in depth and an increase 

 in bottom organisms. 



Ranging between 200 to 400 feet wide, the barrier reef provides 

 a sharp delineation between lagoon and outer platform (Plate 1). 

 The reef is dominantly populated by Milleporidae , Acropora Palmata, 

 Agaricia agaricites and various alcyonarians (Plate 2). At low 

 tide the reef breaks the surface in several areas and, although 

 a few channels provide passage between lagoon and outer platforni, 

 generally presents a solid barrier in the area reconnoitered. 

 Approximately 100 yards south of the southern boundary of the 

 area studied, the solidarity of the reef gives way to scattered 

 heads separated by wide channels 10 to 12 feet deep. 



A sharp increase in depth, and a decrease in coral abundance, 

 marks the eastern or seaward termination of the reef and commence- 

 ment of the outer platform (Plate 2) . Extending approximately 500 

 yards from barrier reef to marginal escarpment, the outer platform 

 ranges from 10 feet to 120 feet deep, and terminates sharply into 

 a precipitous upper marginal or rim escarpment. Between the 

 barrier reef and 20 feet depth the outer platform consists of 

 a hard bottom covered by a thin veneer of coarse sand with 

 occasional gorgonians and scattered massive corals, e.g., 

 Diploria strigosa . In depths greater than 20 feet the population 

 of corals and other marine organisms gradually increases to the 

 point where, between 40 and 60 feet, a virtual forest of corals 

 is present. This "coral forest" is dominated by tall columnar 

 forms of Montastrea annularis . These range from 15 to 20 feet 

 high and are dissected by blindly terminating channels 5 to 10 

 feet wide and floored by a loose, coarse sand (Plate 3). The 

 luxuriance and variety of marine life on this area of the outer 

 platform is extraordinary and attests to the vigorous water 

 circulation necessary to support such a community. Between 60 

 and 80 feet in depth the coral abundance gradually decreases 

 and gives way to low (2 to 4 ft. high) heads arranged generally 

 in a spur and groove configuration normal to the reef. From 



13 



