Defense Date

12-7-2023

Document Type

Thesis

Degree Type

Master of Science

Degree Name

Marine Science

First Advisor

Joana Figueiredo

Second Advisor

Abigail Renegar

Third Advisor

Nicole Fogarty

Keywords

reproduction, histology, Acropora cervicornis, synchronization

Abstract

The persistence of reefs relies on mature corals spawning synchronously to maximize fertilization and produce larvae to replenish local populations. Corals synchronize the release of gametes by responding to temperature, sun, and moon light cycles; however, abnormalities in these patterns can disrupt synchrony. This study is the first to describe regional asynchronous spawning of Acropora cervicornis by quantifying gamete development and spawning times among two reefs, an in situ nursery off Fort Lauderdale, and an in situ nursery in the Florida Keys. While A. cervicornis in the Florida Keys synchronously spawned within the predicted window of 2-5 days after the full moon both years, corals off Fort Lauderdale spawned 7-10 days before the full moon in 2022 and 1-9 days after the full moon in 2023. Additionally, A. cervicornis in Fort Lauderdale also spawn an hour longer than those in the Keys. While regional asynchrony cannot be explained by temperature differences, it remains unclear if light pollution or turbidity drive regional asynchrony. Regardless, it is likely that corals in this region are not receiving the moon light cue for spawning causing asynchronism in both the spawning day and hour of A. cervicornis in Fort Lauderdale. This results in dramatically reduced fertilization success and, consequently, lowers coral recruitment and the ability of reef populations to replenish themselves. A reduction in sexual reproduction and therefore reef connectivity and recruitment will reduce the genetic diversity needed for populations to remain resilient to future disturbances such as marine heat waves.

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