[Coral-List] Rincon, PR, Acropora spawning summary

[Eric Borneman]

Together with observations from the Baums lab, Rincon had an unusual  
spawning year. As reported by Alina Szmant, Ilana Baums and myself  
here, we saw a few colonies of A. palmata spawn on Aug 9 with most  
occurring at the N end of Steps Beach and generally only portions of  
individual colonies.

On Aug 10 spawning occurred in many colonies, mostly from the  
undersides of branches with a spawn slick forming at Steps Beach  
throughout the area but not a complete spawn of all colonies or even  
individual spawning and isolated colonies at the southern Tres Palmas  
side;

August 11 had a similarly large spawn from about the same number of  
colonies as the 10th, forming a slick that moved quickly seaward, and  
generally from upper colony surfaces, and with more colonies spawning  
at the Tres Palmas side. The Baums group had strong spawning at Bajo  
Gallardo.

August 12 had strong spawning in clustered colonies at the southern  
part of Tres Palmas, as monitored by the Baums group. Because of  
strong electrical thunderstorms in the area, we did not get in the  
water to monitor the Steps side.

No colonies were observed spawning on August 13.

Most interesting this year was the timing with spawning moving from a  
north to south direction (chemical signaling?). Previous split spawns  
did not split in this nature or with the underside/upper surface of  
branches spawning, but rather was simply a partial spawn of some  
colonies and not of others. Clearly, spawning was delayed about a day  
or two from their normal timing but within the time frames known for  
the species. Furthermore both we and the Baums group had variable  
sperm quality with some dates showing low sperm motility and mixed  
fertilization rates from low fertilization to >90%. Colonies appeared  
grossly healthy. We took sample core punches of palmata and  
cervicornis and found no oocytes in cervicornis. A. palmata had well  
developed, stage 1-II, or no oocytes in punch core samples.

__________________________
Eric Borneman
Dept. of Biology and Biochemistry
University of Houston