Date of Award

Spring 1997

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Program/Concentration

Ecological Sciences

Committee Director

Mark J. Butler IV

Committee Member

Cynthia M. Jones

Committee Member

Anthony J. Provenzano

Abstract

Recruitment variability of the early life history stages of marine benthic organisms can have profound consequences on population dynamics. I studied factors affecting recruitment success of postlarvae and early juveniles of the Caribbean spiny lobster. I examined patterns in postlarval supply, investigated wind forcing as a potential transport mechanism for recruiting postlarvae, and quantified predation on postlarvae in south Florida, USA. In an eight-year time series, spiny lobster postlarval supply occurred year-round between the new and first quarter lunar phases. The major annual peak occurred around March corresponding to spawning activity ten months earlier, and a smaller non-seasonal peak occurred with a five-month periodicity. Wind forcing of surface waters was correlated to postlarval supply only during winter months, but this accounted for a small proportion of the total variance. During new moon influx, predation on postlarvae tethered to floating arrays was highest over coral patch reefs and declined along a typical transport path over the coastal lagoon and leeward bay, especially near the surface. In contrast, predation during full moon was similar over reefs and the bay probably due to increased exposure to visual predators, whereas predation during new moon was significantly lower in the bay. In laboratory mesocosms, predation was lower under new moon conditions when prey density was low. These results indicate the adaptive value of recruitment during the darkest lunar phase and use of surface waters for rapid transport pass concentrated predator assemblages near reefs. In benthic habitats, predation was highest in coral crevices than in nearshore seagrass or macroalgae. To compare the role of a possible alternative nursery habitat to that of the south Florida system, I studied the population dynamics of juvenile spiny lobsters in mangrove-associated habitats in Belize. Juveniles use mangrove habitats as nurseries, but usage patterns depend on available shelter and isolation of islands which acts to restrict migration of subadult and juvenile lobsters. Settlement presumably occurs in vegetation, but successful recruitment to benthic populations may depend on the proximity of settlers to crevice shelter associated with mangrove islands or patch reefs. The size of a local spiny lobster population may, thus, be influenced by factors affecting postlarval supply to coastal populations, abundance of predators at areas of concentration which postlarvae must traverse, and the availability of suitable settlement habitat.

DOI

10.25777/a3ng-j022

ISBN

9780591603750

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