FW: Spawning in Acropora cervicornis

Precht, Bill Bprecht at pbsj.com
Fri Aug 10 11:06:40 EDT 2001

Dear Coral List:

Yesterday a brief message was sent out alerting us to reproduction in A.
cervicornis off Ft. Lauderdale, Florida.

This is a very important observation... although A. cervicornis is a known
broadcast spawner... in recent years, very few cases of A.c. being "caught
in the act" have been documented.  Reproduction in this species relies
heavily on the asexual fragmentation of the branches... As most of the
readers know, however, this species has undergone catastrophic declines in
populations throughout the region in the last few decades. 

I have included the entire press release from NCRI(thanks to Dick Dodge).

The key now is to see if they  (and others) find high levels of Acropora
recruits in the coming months...

If anyone would like to see a photo of the spawning in progress... contact
the folks at NCRI... (address below)



-----Original Message-----
From: Richard E. Dodge [mailto:dodge at nova.edu] 
Sent: Wednesday, August 08, 2001 8:01 AM
To: Precht, Bill
Subject: Press Release

Press Release


Late on the evening of August 6th a team of researchers from the National
Coral Reef Institute [NCRI] at Nova Southeastern University witnessed a
spawning event of staghorn coral, Acropora cervicornis, located on
Southeast Florida coral reefs off Ft. Lauderdale. Masses of orange
egg-sperm bundles were released into the water column between 11:15 and
11:30 p.m. Sea conditions were a moderate chop and the gametes were carried
south by a strong northerly current. The coral thicket was located in 3.3
meters of water approximately one-half mile offshore. 

This event is noteworthy for several reasons. This is the first time such a
spawning event has been witnessed and documented for corals in Broward
County waters. In addition, the accumulations of staghorn coral demonstrate
that there are healthy reefs existing in some unexpected areas.

The research team, operating out of Nova Southeastern University's
Oceanographic Center in Dania Beach, was comprised of four people:  Dr.
Bernardo Vargas, a postdoctoral researcher at NCRI; Dr. James Thomas,
Research Director at NCRI; Brian Ettinger, a research technician at NCRI;
and Abby Renegar a graduate student at the Oceanographic Center. 

The scientists left the dock at 7 p.m. and anchored near a reef (one of a
number off the Ft. Lauderdale area) that has been a research focus for Dr.
Vargas. A collection net was placed over one colony to trap gametes.
Observations were made from 8 to 11 p.m by the SCUBA diving scientists who
waited for the spawning to occur. 

Coral spawning events, while the subject of much study recently, are
difficult to predict but are generally linked to phases of the moon.  Dr.
Vargas's calculations and results from other researchers indicated that
spawning was expected on August 11, the 6th night after the full moon (and
has been known to occur 7 to 8 days after the full moon).  Prior underwater
observations by Dr. Vargas indicated gamete bundles were increasing in size
and consequently, plans were made to observe the most likely spawning date
of 11 August. Preliminary observation trips to "bracket" the most likely
night were planned, beginning on August 6th. As happens many times in
science, the organisms were not aware of the timetable set for them by
scientists.  Hence, on the first preliminary dive, the team was rewarded by
a spectacular display of nature, a pulse of reproductive activity lasting
approximately 15 minutes.  This is yet another example of how preparation
and luck come together in scientific research.  The team plans to continue
diving through the week to document any more reproductive activity.

 Many corals spawn synchronously, an adaptation thought to overwhelm egg
predators (fish and other marine invertebrates) to which the gametes
represent a high-energy food source. 

Documentation of this event is good news for the coral reef research and
management community. With a steady stream of reports of reef degradation
and death, it is a positive point to note that some reefs continue to
exhibit robust health and growth, even in the most unlikely places.
Located between two major inlets, Hillsboro and Port Everglades, and
adjacent to a densely populated coastal setting, it is reassuring that
reefs are occurring in the shallow waters off Broward County. Subject to
possible runoff and effects of pollution, and extensive coastal development
including modification by high-rise complexes, reefs might not normally be
expected to occur in this setting. Nevertheless, the reefs appear to be
thriving. The irony and highly significant finding is that this staghorn
coral species is persisting, growing, and spawning in a supposed marginal
habitat when most of its brethren species has disappeared or are highly
impacted elsewhere throughout the Florida Keys and Caribbean.  


 NCRI 8000 N. Ocean Dr., Dania, FL 33004 USA   (954) 262-3617   fax
(954)-262-4027  email:  ncri at mako.ocean.nova.edu
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