Quick Look Report: Dendrogyra cylindrus spawning research – July 2018

In July 2018, Nova Southeastern University led a multi-agency effort to observe and collect gametes from spawning pillar coral (Dendrogyra cylindrus) colonies in the Looe Key region of the Lower Florida Keys. Five boats and 23 divers representing six agencies/institutions recorded data and collected eggs and sperm for propagation of the species. Additional observations were conducted on ex situ fragments at Mote Marine Lab, Keys Marine Lab, and Florida Aquarium. Field spawning matched predicted dates, but spawning of males was significantly earlier than in previous years while egg release remained the same. Cryopreservation efforts documented sperm motility of only 1% after one hour. Estimated fertilization rates were consequently much lower than in previous years (< 10% compared to 90%). Laboratory fragments at Keys Marine Lab released eggs in timings consistent with laboratory releases in previous years: later in the night and over an extended number of nights. We posit that these asynchronous releases are the result of a missing environmental cue. In both field and laboratory colonies, observations of inter-year and/or inter-night hermaphroditism was observed. Recently thought to be rare within the species, production of both male and/or female gametes by an individual may be common. Mixed gamete solutions were transferred to Florida Aquarium and Mote Marine Lab; low levels of cell division and larval swimming were documented, but no settlers have yet been found. Mote will further assess settlement tiles in coming weeks.