Date: Wed, 21 Aug 1996 19:15:01 -0400 (EDT) From: Coral Health and Monitoring Program To: coral-list@reef.aoml.noaa.gov Subject: Coral Spawning/Gulf of Mexico (fwd) ---------- Forwarded message ---------- Date: 21 Aug 1996 16:32:25 -0400 From: "Deslarzes, Ken" To: Coral Health and Monitoring Program Subject: Coral Spawning/Gulf of Mexico From: Gregory S. Boland, Dept. of Oceanography, Texas A&M University, College Station, Texas 77843, USA. Ph. 409-845-8387 -Copy of a Press Release- Seven evenings after the full moon of July; Flower Gardens Banks National Marine Sanctuary (NW Gulf of Mexico), August 6, 1996. The corals continue to surprise all the coral reef biologists, including this one after five years of observation and research. I would have bet, along with virtually every one else, that the odds were very small of seeing any spawning at the Flower Gardens this early in August, but the Flower Gardens surprised us yet again. On the night of August 6th, seven evenings after the full moon of July 30, the Flower Gardens impressed a large number of volunteer research divers from Oceanographic Expeditions with a mass spawning event (albeit very reduced in comparison to previous year's events). In comparison to other sites throughout the Atlantic and Caribbean during normal events, even a reduced mass spawning at the Flower Gardens appears quite spectacular. The first witnessed coral spawning occurred at 20:55 hrs CDT from both male and female Montastraea cavernosa. One dive team also recorded a mass egg bundle release from a single Diploria strigosa head at 21:30 hrs. This author entered the water at 21:45 and shortly after came across the head of a female M. cavernosa releasing rather loose aggregations of tiny eggs. In previous years, this diecious species extruded much more agglutinated egg masses than what was seen this year in August. Individual eggs rapidly separated from each other as they were expelled from each polyp. A total of three different species were seen spawning between a narrow time window of 20:55-22:20 hrs. These included D. strigosa, Montastraea franksi and both sexes of M. cavernosa. People on the vessel also reported a limited presence of a spawn slick on the water's surface roughly during the same period. Ten divers entered the water for a third dive sequence on the evening of August at 23:55 hrs. None observed any evidence of spawning during their dive of approximately 35 minutes and no other coral eggs were observed on the surface for the rest of the evening up to at least 02:00 hrs of 7 August. The second night of the cruise did not result in any diver observations of spawning between the hours of 20:30-21:30 hrs but there were observations of coral egg bundles on the surface. The species producing the egg bundles was not positively identified but appeared to be from a M. franksi. Several heads of D. strigosa were observed and photographed by this author underwater in pre-spawning "setting stage". The vast majority (>95%) of the other D. strigosa heads did not show any signs of a setting stage. A very brief appearance of egg bundles also appeared on the surface at 21:30 hrs during the night of 8 August, 9 evenings after the full moon. This is the time frame for the spawning of Colpophyllia natans, but the observed egg bundles were much smaller that the normal baby pea-sized C. natans egg bundles. The observed bundles could have been from a single head due to the very short duration (2-3 min) the spawn drifted past the vessel. There is little doubt that the 3 or 4 September coral spawning event will be quite spectacular, but then, we have been fooled before.