in juvenile queen conch mortality ( Jory 1982; Iversen et al. 

 1986). 



Relatively little is known, however, about the factors 

 controlling recruitment, habitat selection, density dependency 

 and survival during the first months of settlement. In this 

 paper we present preliminary biological information on the life 

 history of S^ gigas from the southern Exuma Cays, Bahamas, during 

 1984, 1985 and 1986. 



Study Site 



The southern Exuma Cays lie on the southwestern edge of 

 Exuma Sound on the Great Bahama Bank, 110 miles southeast of 

 Nassau, Bahamas (Fig. 1). The overall study area is in the 

 vicinity of Lee Stocking Island (23°45'N, 76°10'W), site of the 

 Caribbean Marine Research Center ( CMRC ) . Most of the study sites 

 on the western side of the Cays have strong tidal currents, 

 particularly between islands, resulting in shifting sand banks. 

 Temperatures range from about 21°C in February to 30°C in August 

 and September. Salinity ranges from 36 ppt to an occasional 40 

 ppt. The bottom is characterized by stable subtidal sand and 

 seagrass flats, comprised primarily of turtlegrass ( Thalassia 

 testudinum) and high concentrations of the calcareous algae 

 Rhipoceohalus , Penicillus and Halimeda species. Mounds produced 

 by the shrimp Callianassa are common in the same area. 



The bottom is stabilized by an organic mat consisting 

 primarily of algae, diatoms and the rhizomes of T_^ testudinum . 

 The stabilized grassflats contain ooids, pellets, grapestones and 

 fine-grain carbonates (Kendall and Dill 1987). 



The eastern side of the Cays is characterized by a 

 typically open ocean profile (2m- >30 m), coral reefs, sand 

 flats and smooth rising relic coral reef mounds. 



Norman's Pond Cay (Fig. 2, Site A) is characterized by an 

 old salt production pond (about 80 acres) with an effluent 

 channel on the western side of the Cay. Sand and beachrock lie 

 north and south of the channel entrance. A partial dike at the 

 entrance to the channel maintains water level in the pond about 

 two feet above the surrounding sea during the ebbing and low 

 tides, resulting in an outward flow most of the day. For a short 

 period during high tide, when the level of the sea is above the 

 dike, the flow is into the pond. 



The site of the Children's Bay Cay S^ gigas nursery area 

 (Fig. 2, Site B) is characterized by a large bed of T. 

 testudinum adjacent to an unstable ooid shoal to the west and a 

 moderately deep channel ( >7 m) to the east. The nursery 

 ground is primarily in a grass bed at a depth of 3-5 m which 

 extends onto a shallow sand shoal (1-2 m). 



348 



