Coral spawn timing is a direct response to solar light cycles and is not an entrained circadian response
- 467 Downloads
Broadcast spawning corals release gametes into the oceans with extraordinarily accurate timing. While the date of spawning is set by the lunar cycle, the hour/minute of spawning is set by the solar cycle. In this report, we describe experiments that test whether the time of spawning is regulated by an entrained biological clock or whether it is directly controlled by the solar cycle. Montastraea franksi samples were collected on the morning of the predicted spawning. Fragments from colonies were kept under three different lighting conditions and spawning monitored. The three conditions were sunset times of 0, 1 or 2 h earlier than normal. Fragments from the same colony spawned differently under these three conditions, with an early sunset causing a corresponding early shift in spawning. These results indicate that spawn timing is not controlled by a circadian rhythm and that it is directly controlled by local solar light cycle.
KeywordsBroadcast spawning Circadian rhythm Biological clock Mass spawning
This research was supported by NOAA and the Flower Garden Banks National Marine Sanctuary. Additional support was provided by Galatee Films by providing ship time and we would like to especially thank Antoine de Cozette for help in coordinating field work. Field work was aided by Sarah Davies, Kurt Carlson, Jay Reichman, Mike Nickell, Emma Hickerson and the crew of the M.V. Fling.
- Babcock RC (1984) Reproduction and distribution of two species of Goniastrea (Scleractinia) from the Great Barrier Reef province. Coral Reefs 2:187–195Google Scholar
- Dunlap JC, Loros JL, DeCoursey PJ (2004) Chronobiology: biological timekeeping. Sinauer Associates, Inc., Sunderland, MAGoogle Scholar
- Gorbunov MY, Falkowski PG (2002) Photoreceptors in the cnidarian hosts allow symbiotic corals to sense blue moonlight. Limnol and Oceanogr 47:309–315Google Scholar
- Hagman DK, Gittings SR, Deslarzes KJ (1998) Timing, species participation, and environmental factors influencing annual mass spawning at the Flower Garden Banks (northwest Gulf of Mexico). Gulf Mex Sci 16:170–179Google Scholar
- Hunter CL (1988) Environmental cues controlling spawning in two Hawaiian corals, Montipora verruscosa and M. Dilatata. Proc 6th Int Coral Reef Symp 2: 727-732Google Scholar
- van Veghel ML (1993) Multiple species spawning on Curacao. Bull Mar Sci 52:1017–1021Google Scholar
- Vize PD, Embesi JA, Nickell M, Brown DP, Hagman DK (2005) Tight temporal consistency of coral mass spawning at the Flower Garden Banks, Gulf of Mexico, from 1997–2003. Gulf Mex Sci 23:107–114Google Scholar
- Wallace CC, Babcock RC, Harrison PL, Oliver JK, Willis BL (1986) Sex on the reef: mass spawning of corals. Oceanus 29:38–42Google Scholar
- Willis BL, Babcock RC, Harrison PL, Oliver JK (1985) Patterns in the mass spawning of corals on the Great Barrier Reef from 1981 to 1984. Proc 5th Int Coral Reef Congr 4: 343–348Google Scholar