title: Reproductive natural history and successful juvenile propagation of the threatened Caribbean pillar coral Dendrogyra cylindrus.
abstract: BACKGROUND
  The Caribbean pillar coral Dendrogyra cylindrus was recently listed as a threatened species under the United States Endangered Species Act. One of the major threats to this species is its low, virtually undetectable recruitment rate. To our knowledge, sexually-produced recruits have never been found in over 30 years of surveys of Caribbean reefs. Until recently, the reproductive behavior of D. cylindrus was uncharacterized, limiting efforts to study its early life history, identify population bottlenecks, and conduct outplanting projects with sexually-produced offspring. In Curaçao, we observed the spawning behavior of this species over three years and five lunar cycles. We collected gametes from spawning individuals on three occasions and attempted to rear larvae and primary polyp settlers.
  
  
  RESULTS
  Here we describe successful fertilization methods for D. cylindrus and we document rapid embryonic development. We describe the successful propagation of embryos to the swimming larvae stage, the first settlement of larvae in the laboratory, and the survival of primary polyp settlers for over seven months. We show that spawning times are highly predictable from year to year relative to the lunar cycle and local sunset times. We use colony-level data to confirm that males begin spawning before females. We also provide the first reports of split-spawning across months in this species.
  
  
  CONCLUSIONS
  Together, our findings of consistent spawning times, split-spawning, rapid embryonic development, and remarkable robustness of larvae and settlers now enable expanded research on the early life history and settlement ecology of D. cylindrus. This will help biologists to identify the population bottlenecks in nature that underlie low recruitment rates. Further, the settlement of D. cylindrus larvae in the laboratory now makes out-planting for restoration more feasible. Asynchronous spawning times and rapid embryonic development may have important consequences for population biology, connectivity, and management, by affecting fertilization dynamics and larval dispersal distances. We argue that a precautionary approach to conservation is warranted, given this species' peculiar life history traits and still-unresolved population structure. Overall, the natural history and husbandry contributions presented here should facilitate accelerated research and conservation of this threatened coral.
authors.affiliation: CARMABI Foundation, Piscaderabaai z/n, PO Box 2090, Willemstad, Curaçao. kristen@marhaverlab.com.|School of Natural Sciences, University of California at Merced, 5200 North Lake Road, Merced, CA, 95343, USA. kristen@marhaverlab.com.
authors.forename: Kristen L
authors.initials: KL
authors.lastname: Marhaver
authors.affiliation: CARMABI Foundation, Piscaderabaai z/n, PO Box 2090, Willemstad, Curaçao. m.vermeij@carmabi.org.|Aquatic Microbiology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 700, 1098 XH, Amsterdam, The Netherlands. m.vermeij@carmabi.org.
authors.forename: Mark J A
authors.initials: MJ
authors.lastname: Vermeij
authors.affiliation: School of Natural Sciences, University of California at Merced, 5200 North Lake Road, Merced, CA, 95343, USA. monicamedina@psu.edu.|Current Address: Department of Biology, Pennsylvania State University, 324 Mueller Lab, University Park, PA, 16802, USA. monicamedina@psu.edu.
authors.forename: Mónica M
authors.initials: MM
authors.lastname: Medina
mesh_terms: D000818:Animals; D037421:Anthozoa / Q000502:physiology*; D017691:Caribbean Region; D003247:Conservation of Natural Resources; D056727:Endangered Species; D005260:Female; D005306:Fertilization; D005854:Germ Cells / Q000502:physiology; D007814:Larva / Q000254:growth & development; D008297:Male; D012098:Reproduction