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Florida Fish and Wildlife Conservation Commission Logo Florida’s State Wildlife Grants Program Funded Projects

Evaluating the Role of the Predatory Snail, Thais deltoidea, on Enhancing Survival of Outplanted Staghorn Corals as Part of a Comprehensive Coral Reef Restoration Strategy
Gabriel Delgado , FWC
Abstract: Coral reefs in the Florida Keys, like those elsewhere in the Caribbean, have degraded due to numerous stressors. Staghorn and Elkhorn coral (Acropora spp.) in particular have undergone widespread declines and are now listed as threatened under the US Endangered Species Act. These species are vital for both the accretion of new reef and providing structural habitat for a variety of fishes and invertebrates. Such is the importance of these corals that they have been included on the Florida Wildlife Initiative’s list of Species of Greatest Conservation Need (SGCN), and the re-establishment of these species is widely viewed as the first step in proactive attempts to restore Florida’s reefs. However, the effects of predation on both remnant wild populations and nursery-propagated colonies of these two coral species have been profound. The corallivorous snail, Coralliophila abbreviata, in particular has been identified as the primary source of chronic mortality of these corals. At present, attempts to remove these predators from newly outplanted coral colonies has been marginally effective and requires substantial time and effort, and will therefore not be feasible in large-scale coral restoration activities. The carnivorous deltoid rock snail, Thais deltoidea, occurs in the same coral reef habitat as C. abbreviata. Observations in the laboratory are that Thais deltoidea does its foraging at night and the interaction between these two species is that T. deltoidea readily preys upon C. abbreviata. Preliminary results show that T. deltoidea targeted the smaller C. abbreviata individuals first. In that vein, the relative size difference between predator and prey also influenced attack success. The relative size difference between T. deltoidea and C. abbreviata was significantly larger in successful attacks than unsuccessful attacks. Thais deltoidea were, on average, 15 mm larger than C. abbreviata in successful attacks. Consequently, understanding the predator/prey dynamics between these species could ultimately aid in the development of a comprehensive coral reef restoration strategy for Florida by identifying coral reef restoration locations and conditions where predation upon newly restocked coral colonies by corallivorous snails would be minimized by the presence of T. deltoidea. However, research to this point has only documented the trophic interactions between these two species at a simplistic level. Although the results are intriguing, they do not address a host of questions about this trophic interaction that would allow assessment to what extent it may shape the coral reef community and, in particular, the survival of Acroporid corals. Predator-prey trophodynamics are complex and influenced by numerous factors including prey selectivity behavior, prey encounter rates, the probability of attack by the predator given such encounters, and the success of these attacks. The proposed research in this project will address some of these unknown trophic interactions. This proposed research is part of a broader coral reef restoration strategy being developed by various agencies, organizations, and individuals. This restoration strategy also incorporates collaborative efforts to restore wild coral colonies through the cultivation of corals for eventual outplanting on Florida’s coral reefs. For example, the FWC and Mote Marine Laboratory are collaborating with several organizations and the NOAA restoration center to develop and expand in situ coral nurseries in the Florida Keys. The proposed research provides an essential complement to these coral restoration efforts that will complete a strategy aimed at restoring the health and resiliency of Florida’s reef ecosystem.
Award Matching Funds Total
$22,678.00 $12,211.00 $34,889.00
Year Funded Starting Date Ending Date
2013 7/1/2014 4/30/2016

Location: Monroe

Final report