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Title: The reproductive ecology of two corals and one gorgonian from sub-tropical Bermuda
Author: de Putron, S. J.
Awarding Body: University of Wales Swansea
Current Institution: Swansea University
Date of Award: 2003
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This study examines the sexual reproductive ecology of three species of corals common on the sub-tropical reefs of Bermuda: the scleractinians Porites astreoides and Madracis mirabilis, and the gorgonian Pseudoplexaura porosa. The reproductive biology of corals in Bermuda is of particular interest because low winter seawater temperatures and geographical isolation make it an extreme of distribution for many of the species there. In addition, the Bermuda platform comprises reef zones that experience gradients of temperature, sediment loading and wave intensity at the different depths. The objectives are twofold: firstly, information is presented on the reproductive mode, sexuality and fecundity of the corals, and the occurrence of lunar periodicity to gamete development, planula release or spawning. The second objective addresses the question of whether environmental variability across the Bermuda platform and between years alters the reproductive cycles of these species. The study species varied in reproductive mode and sexuality. The scleractinian Porites astreoides is a brooder with a mixed sexuality; the gorgonian Pseudoplexaura porosa exhibits gonochorism with broadcasting, and the scleractinian Madracis mirabilis has hermaphroditic colonies with a proposed intermediate 'pseudo-brooding' reproductive mode. Fecundity was variable within and between Po. astreoides colonies but was not related to colony size. There was a relationship between polyp size and gamete production in Ps. porosa. The synchrony of lunar periodicity to spawning or planulae release varied between the species and this is related to the difference reproductive modes. The extent that planula release of Po. astreoides was synchronised to the lunar cycle also varied according to the reef zone in Bermuda, a proposed consequence of variable turbidity levels from inshore to offshore. Observed differences in the reproductive effort of Po. astreoides and Ps. porosa, both at the different reef zones within Bermuda, as well across study years, are related to spatial and inter-annual variations in temperature profiles.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available