Abstract
Juvenile queen conch (Strombus gigas L.) occur in discrete aggregations within seemingly uniform seagrass beds throughout the Exuma Cays, Bahamas, suggesting that the aggregations occupy ecologically unique sectors of the habitat or that conch gain fitness by aggregated distribution. To examine the structure of a juvenile aggregation and to determine the underlying mechanisms which affect juvenile conch distribution, we axamined density, size composition, growth, survivorship, and movement patterns within a typical tidal-flow field nursery over a 14 mo period (August 1989 to September 1990). At the beginning of the study in August 1989, the conch population occupied 16.7 ha, with densities>0.2 juvenile conch m-2. The aggregation formed an ellipse, with longitudinal axis parallel to the main axis of the tidal current. Surveys conducted every 2 mo showed that conch density in the aggregation center remained constant while all other zones had lower densities which varied with time. In areas of high population density within the aggregation, several mass migrations of juveniles (20 to 99 conch m-2) occurred in early 1990. Tagged juveniles transplanted to zones outside the aggregation had high growth rates but suffered higher losses than individuals transplanted to the aggregation center. A tethering experiment confirmed the hypothesis that predator-induced mortality is significantly higher outside than inside the conch aggregation. Our results suggest that the queen conch aggregation occupied only a portion of the habitat that is optimal for feeding and growth. Aggregations could be maintained by differential mortality over a site; however, predation rates are probably density-dependent. Gregariousness, observed in translocation experiments, may provide an active mechanism for maintaining aggregated distribution and reducing mortality in conch nurseries. The ecological significance of aggregations should be considered in fisheries management and stock enhancement programs with queen conch.
Similar content being viewed by others
Literature cited
Alcolado, P. M. (1976). Crecimiento, variaciones morfologicas de la concha y algunas datos biologicos del cobo Strombus gigas L. (Mollusca, Mesogastropoda). Serie oceanol. Acad. Cienc. Cuba, Inst. Oceanol., Habana 34: 1–36
Andrew, N. L. (1991). Changes in subtidal habital following mass mortality of sea urchins in Botany Bay, New South Wales. Aust. J. Ecol. 16: 353–362
Appeldoorn, R. S. (1984). The effect of size on mortality of small juvenile conchs (Strombus gigas Linne and S. costatus Gmelin). J. Shellfish Res. 4: 37–43
Aronson, R. B. (1989). Brittlestar beds: low predation anachronisms in the British Isles. Ecology 70: 856–865
Ballantine, D. L., Appeldoorn, R. S. (1983). Queen conch culture and future prospects in Puerto Rico. Proc. Gulf Caribb. Fish. Inst. 35: 57–63
Berg, C. J., Jr. (1976). Growth of the queen conch Strombus gigas, with a discussion of the practicality of its mariculture. Mar. Biol. 34: 191–199
Berg, C. J., Jr., Olsen, D. A. (1989). Conservation and management of queen conch (Strombus gigas) fisheries in the Caribbean. In: Caddy, J. F. (ed.) Marine invertebrate fisheries: their assessment and management. Wiley, New York, p. 421–442
Bernstein, B. B., Williams, B. E., Mann, K. H. (1981). The role of behavioral responses to predators in modifying urchins' (Strongylocentrotus droebachiensis) destructive grazing and seasonal foraging patterns. Mar. Biol. 63: 39–49
Caddy, J. F. (1989). A perspective on the population dynamics and assessment of scallop fisheries, with special reference to the sea scallop, Placopecten magellanicus Gmelin. In: Caddy, J. F. (ed.), Marine invertebrate fisheries: their assessment and management. Wiley, New York, p. 559–589
Carpenter, R. C. (1981). Grazing by Diadema antillarum (Philippi) and its effects on the benthic algal community. J. mar. Res. 39: 749–765
Catterall, C. P., Poiner, I. R. (1983). Age- and sex-dependent patterns of aggregation in the tropical gastropod Strombus luhuanus. Mar. Biol. 77: 171–182
Chesher, R. H. (1969). Destruction of Pacific corals by the sea star Acanthaster planci. Science, N.Y. 165: 280–283
Davis, M., Hesse, C., Hodgkins, G. (1985). Commercial hatchery procedures for queen conch Strombus gigas, seed for the research and grow-out market. Proc. Gulf Caribb. Fish. Inst 38: 326–335
Davis, M., Stoner, A. W. (1993). Metamorphosis of queen conch larvae: the role of gregariousness and trophic cues. (In preparation)
Hesse, K. O. (1979). Movement and migration of the queen conch, Strombus gigas, in the Turks and Caicos Islands. Bull. mar. Sci. 29: 303–311
Iversen, E. S., Rutherford, E. S., Bannerot, S. P., Jory, D. E. (1987). Biological data on Berry Islands (Bahamas) queen conchs, Strombus gigas, with mariculture and fisheries management implications. Fish. Bull. U.S. 85: 299–310
Laughlin, R. A., Weil, M. E. (1983). Queen conch mariculture and restoration in the Archipelago de Los Roques. Proc. Gulf Caribb. Fish. Inst. 35: 64–72
Lowe, E. F., Turner, R. L. (1976). Aggregation and trail-following in juvenile Bursatella leachii pleii. Veliger 19: 153–155
Marshall, L. S., Jr. (1992). Survival of queen conch, Strombus gigas, in natural seagrass habitats: impact of prey, predator and habitat features. Ph.D. disseration. College of William and Mary, Williamsburg, Virginia
Ogden, J. C., Brown, R. A., Salesky, N. (1973). Grazing by the echinoid Diadema antillarum Philippi: formation of halos around West Indian patch reefs. Science, N.Y. 182: 715–717
Ormond, R. F. G., Campbell, A. C., Head, S. H., Moore, R. J., Rainbow, P. R., Saunders, A. P. (1973). Formation and breakdown of aggregations of the crown of thorns starfish, Acanthaster planci (L.). Nature, Lond. 246: 167–168
Randall, J. E. (1964). Contributions to the biology of the queen conch, Strombus gigas. Bull. mar. Sci. Gulf Caribb. 14: 246–295
Scheibling, R. E. (1985). Directional movement in a sea star (Oreaster reticulatus): adaptive significance and ecological consequences. Contr. mar. Sci. Univ. Tex. (Suppl) 27: 244–256
Stoner, A. W. (1989). Winter mass migration of juvenile queen conch, Strombus gigas, and their influence on the benthic environment. Mar. Ecol. Prog. Ser. 56: 99–104
Stoner, A. W. (1993). Significance of habitat and stock pre-testing for enhancement of natural fisheries: experimental analyses with queen conch. (in preparation)
Stoner, A. W., Davis, M. (1993). Experimental outplanting of juvenile queen conch (Strombus gigas): comparison of wild and hatchery-reared stocks. (in preparation)
Stoner, A. W., Hanisak, M. D., Smith, N. P., Armstrong, R. A. (1993). Large-scale distribution of queen conch nursery habitats: implications for stock enhancement. In: Appeldoorn, R. S., Rodriguez, B. (eds.) The biology, fisheries, mariculture and management of the queen conch. Fundación Cientifica Los Roques, Caracas, Venezuela (in press)
Stoner, A. W., Lally, J. (1993). High-density aggregation in queen conch, Strombus gigas: formation, patterns, and ecological significance. (in preparation)
Stoner, A. W., Lipcius, R. N., Marshall, L. S., Jr., Bardales, A. T. (1988). Synchronous emergence and mass migration in juvenile queen conch. Mar. Ecol. Prog. Ser. 49: 51–55
Stoner, A. W., Sandt, V. J. (1991). Experimental analysis of habitat quality for juvenile queen conch in seagrass meadows. Fish. Bull. U.S. 89: 693–700
Stoner, A. W., Sandt, V. J., Boidron-Metairon, I. F. (1992). Reproductive activity of queen conch, Strombus gigas, and the abundance of veligers. Fish. Bull. U.S. 90: 161–170
Stoner, A. W., Waite, J. M. (1990). Distribution and behavior of queen conch, Strombus gigas, relative to seagrass standing crop. Fish. Bull. U.S. 88: 573–585
Stoner, A. W., Waite, J. M. (1991). Trophic biology of Strombus gigas in nursery habitats: diets and food sources in seagrass meadows. J. mollusc. Stud. 57: 451–460
Weil, M.E., Laughlin, R. (1984). Biology, population dynamics, and reproduction of the queen conch, Strombus gigas Linné, in the Archipelago de Los Roques National Park. J. Shellfish Res. 4: 45–62
Wicklund, R. I., Hepp, L. J., Wenz, G. A. (1991). Preliminary studies on the early life history of the queen conch, Strombus gigas, in the Exuma Cays, Bahamas. Proc. Gulf Caribb. Fish. Inst. 40: 283–298
Author information
Authors and Affiliations
Additional information
Communicated by N. Marcus, Tallahassee
Rights and permissions
About this article
Cite this article
Stoner, A.W., Ray, M. Aggregation dynamics in juvenile queen conch (Strombus gigas): population structure, mortality, growth, and migration. Marine Biology 116, 571–582 (1993). https://doi.org/10.1007/BF00355476
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00355476