Abstract.- Allozymes were used 

 tx) examine spatial and temporal com- 

 ponents of genetic variation among 

 populations of queen conch in the 

 Florida Keys and Bimini over a 4- 

 year period. Spatial and temporal 

 genetic variation were both signifi- 

 cant (F< 0.001) despite high levels of 

 genetic similarity among samples 

 (mean Nei's I, 0.994). However, no 

 consistent pattern of variation was 

 observed. The gene diversity among 

 localities (Glt 0.50%) did not differ 

 significantly (P>0.05) from the diver- 

 sity among years or samples within 

 locahties (Gsl 0.60%). In addition, 

 Florida Keys and Bimini populations 

 were very similar genetically to 

 those studied previously in the Carib- 

 bean Sea and Bermuda (mean Nei's 

 I, 0.988). In general, populations of 

 queen conch appear to be structured 

 as a mosaic of spatial and temporal 

 genetic patchiness within a continu- 

 um of high genetic similarity. This 

 genetic similarity is presumably main- 

 tained by larval drift and gene flow. 

 However, the observed patterns of 

 genetic variation suggest a dynamic 

 population structure. This structure 

 may reflect presettlement stochastic 

 events and processes in the marine 

 environment. 



Genetic patchiness among 

 populations of queen concli 

 Strombus gigas in tlie 

 Florida Keys and Bimini* 



Donald E. Campton 



Department of Fisheries and Aquaculture, University of Florida 

 7922 NW 7 1 St Street, Gainesville, Florida 32606-0300 



Carl J. Berg Jr. 



Florida Marine Research Institute, Florida Department of Natural Resources 

 13365 Overseas Highway, Marathon, Florida 33050 

 Current address: P,0 Box 769, Kilauea, Hawaii 90754 



Lynn M. Roblson 



Department of Fisheries and Aquaculture, University of Florida 

 7922 NW 71st Street, Gainesville, Florida 32606-0300 

 Current address: Department of Fisheries and Allied Aquacultures 

 Auburn University, Auburn, Alabama 36849 



Robert A. Glazer 



Florida Marine Research Institute, Florida Department of Natural Resources 

 13365 Overseas Highway, Marathon, Florida 33050 



The queen conch Strombus gigas is a 

 large marine gastropod of significant 

 economic importance to the Carib- 

 bean Sea area (reviewed by Berg and 

 Olsen 1989). The native range of the 

 species extends from south Florida 

 to Venezuela and eastward from 

 Central America to the Bahama and 

 West Indies Islands. An isolated 

 population also inhabits the coastal 

 waters of Bermuda. The species has 

 been heavily exploited in commercial, 

 recreational, and subsistance fisher- 

 ies throughout its geographic range. 

 Many populations are considered 

 depleted or overfished. 



The life history of queen conch sug- 

 gests the potential for extensive gene 

 flow through larval dispersal (Schel- 

 tema 1971, 1986). Laboratory studies 

 indicate that larvae maintain the 

 planktonic stage for 12-35 days (x 

 21 days) before settling and meta- 



Manuscript accepted 4 March 1992. 

 Fishery Bulletin, U.S. 90:250-259 (1992). 



* Journal Series R-01534, Florida Agricultural 

 Experiment Station. 



morphosis (Ballantine and Apple- 

 doorn 1983, Davis and Hesse 1983). 

 Larvae entrained in swift, Caribbean 

 currents (l-3km/h) could thus be 

 transported significant distances 

 (Kinder et al. 1985). However, disper- 

 sal and recruitment patterns of S. 

 gigas during the planktonic stage are 

 largely unknown. Effective manage- 

 ment and rehabilitation of the spe- 

 cies throughout its geographic range 

 necessitate an understanding of pop- 

 ulation structure, patterns of gene 

 flow, and genetic relationships. 



In a recent allozyme study, Mitton 

 et al. (1989) found a high level of 

 genetic similarity among populations 

 of queen conch from eight localities 

 throughout the Caribbean Sea. How- 

 ever, significant spatial heterogen- 

 eity in allele frequencies indicated 

 that the sampled populations were 

 not totally panmictic. In addition, 

 allele frequencies for the geograph- 

 ically disjunct population of Bermuda 

 were distinctive at one locus. 



250 



