Fishery Bulletin 91(3), 1993 



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GREAT BAHAMA BANK 



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Sand 

 Bar 



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 IZone CI 



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LOW WATER B '•'"•'' ... ..-/<'•------ q . '.- 



NEIGHBOR CAY 



Figure 2 



Detailed map of the Neighbor Cay, Bahamas, study site showing the habitat zones where environ- 

 mental measurements and conch density were made. Zones A, B, C, and D are bare sand. Zones E, 

 F, and G are vegetated with turtlegrass (Thalassia testudinum). Numbers at the mean low water 

 line (MLW) indicate positions of transects which ran perpendicular to the beach. 



above-ground parts of the macrophytes were separated 

 by species and dried at 80°C for 24 hours. The indi- 

 vidual components were weighed (O.lg) and biomass 

 was expressed in g dry weight/m 2 . Water depth was 

 measured at mean low water at every station in each 

 zone. 



Conch distribution 



Conch density (no./m 2 ) was determined in January 1989 

 at each station by searching two 0.75-m radius circles 



(to 10cm depth) to extract buried conch. Preliminary 

 observations at the Neighbor Cay study site showed 

 that burial depth was limited to 3-4 cm for 35-54 mm 

 conch. All conch were counted and measured for shell 

 length (SL, spire to siphonal groove). 



In early February 1989, heavy mortality due to pre- 

 dation reduced the early juvenile population by at least 

 50%. Crushed shells of small conch were abundant in 

 all of the primary habitats, and crabs were the sus- 

 pected predators. Few free-ranging, tagged conch were 

 found alive after that time. 



