Evaluation of Substrate Properties for Settlement of Caribbean Staghorn Coral Acropora cervicornis Larvae in a Land-Based System

Abstract

Stony coral culture has recently been the focus of increasing interest and effort, with most production taking place by asexual reproduction through fragmentation. In corals grown for reef restoration, techniques for sexual propagation offer the potential to increase genetic diversity of species for which this is a concern. After decades of population decline, the Caribbean staghorn coral Acropora cervicornis was listed as threatened under the U.S. Endangered Species Act in 2006, along with its congener, elkhorn coral A. palmata. We used practical large-scale, land-based culture conditions with aquaria set up in a choice/no-choice design to test three substrate properties for their influence on settlement and metamorphosis in staghorn coral planula larvae. This transitional life stage is critical for sexual reproduction and currently represents a culture bottleneck. A total of 999 live primary polyps were produced across all experimental substrates. Planula larvae showed significant preference for substrates that were biologically conditioned, top oriented, and rugose. Conditioning was essentially prerequisite for settlement and metamorphosis, with orientation and texture also affecting larval settling. Although the ideal combination of substrate properties produced lower settling and metamorphosis rates than those observed in smaller-scale culture experiments with elkhorn coral, results are informative in the development of reliable aquaculture techniques for sexual propagation of Caribbean Acropora in land-based systems.

Received February 10, 2016; accepted April 27, 2016

Acknowledgments

Thanks to the Coral Restoration Foundation for work throughout the year identifying spawning colonies and providing hospitality, resources, and access to corals during the spawning period. Thanks also to The Florida Aquarium for providing resources during the spawning period and assistance in all aspects of gamete collection and fertilization and to the University of Florida Tropical Aquaculture Lab for providing resources during the settling experiment.