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A dynamic filter to larval dispersal in a reef-building coral
L.M. Cherubin, I.B. Baums, and C. Paris
University of Miami
lcherubin@rsmas.miami.edu(Abstract received 05/20/2005 for session A)
ABSTRACT
The movements of larvae between marine populations are difficult to follow directly and have been the subject of much controversy, especially in the Caribbean. The debate centers on the degree to which populations are demographically open, such that depleted populations can be replenished by recruitment from distant healthy populations, or demographically closed and thus in need of local management. Given the depressed state of many tropical reef populations, understanding of these movements now bears critically on the number, placement, and size of marine reserves. Genetic analyses have shown that populations of the Caribbean reef-building coral, Acropora palmata, have experienced little or no recent genetic exchange between the western and eastern Caribbean. Puerto Rico was identified as an area of mixing between the two subregions. Here, we aim to verify the plausibility of a present day oceanographic barrier in the vicinity of Mona Passage using two larval migration numerical models, based on both life history characteristics and physical forcing. The models differed in spatial scales with one simulating Caribbean-wide dispersal and the other focused on dispersal in the Mona Passage. Our results from the larger scale dispersal experiment confirmed that there was no significant larval exchange between the eastern and western Caribbean, driven by the large scale flow. The smaller scale numerical model indicated that virtual larvae released from localities on both sides of the Mona Passage did not readily traverse the passage during the August spawning season, while those released from Mona Is. were retained in the lee within topographically steered eddies. These eddies formed partly as a result of the steep topography of Mona Island and acted as a defacto barrier to dispersal of the largely passive coral larvae. The comparison of genetic and coupled physical-behavioral models of larval movements is a powerful tool to address dispersal over several time scales.
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2005 LAPCOD Meeting, Lerici, Italy, June 13-17, 2005