Information on reproduction in reef corals is presented. An understanding of its reproductive behaviour is an important factor in helping to preserve the coral reef ecosystems.Coral reefs, Spawning

Noordeloos, M.

Oliver, J.

Yusuf, Y.

English

Research Papers in Economics

NAGA, WorldFish Center Quarterly  Vol. 26 No. 4 Oct-Dec 2003 28
articles
The timing of reproduction in reef corals 
has received considerable attention in 
recent years. Understanding the 
reproductive behavior of corals can be an 
important factor in helping to preserve 
coral reef ecosystems. Coral spawning 
and reproduction allows corals to inhabit 
other geographic areas and recover from 
damage or stressful events. During their 
larval stage, corals can travel hundreds of 
kilometers and can eventually settle on 
reefs quite far from where they were 
spawned.  Depending on ocean currents, 
some reefs could be dependent on 
upstream reefs for most of their new 
recruits. Thus, the destruction of a single 
coral reef area can have devastating 
consequences for other reefs that are 
connected to it.
The sexual reproduction of corals can be 
classiﬁ  ed as either brooding or spawning. In 
brooding, only male gametes are released 
Coral spawning information
into the water and these are then taken in 
by female corals containing egg cells. 
Brooding happens when those eggs are 
fertilized and develop internally into fully 
developed larvae, which are released in a 
process known as planulation. Spawning, 
on the other hand, refers to the process 
in which corals release sperm and eggs to 
be fertilized outside of the individual (i.e. 
in the water column).
  
Brooding
In brooding coral eggs are fertilized 
internally and fully developed larvae are 
released in a process known as 
planulation. Many brooding species have 
several reproductive cycles through the 
year, usually with a monthly periodicity. 
Planulae of brooding species that are 
released at an advanced developmental 
stage may be able to settle quickly near 
the parent colony compared with the 
planulae of spawning species. Planulae in 
brooding species usually have limited 
dispersal rates and they settle quickly 
near the parent colony, although some 
studies have shown that they are also 
capable of dispersing over long distances.
  
Spawning
It was previously thought that the 
majority of the scleractinian corals are 
viviparous or brooders. Recent studies 
suggest that the majority of coral species 
are hermaphroditic (dual sex) or 
gonochoric (single sex) broadcasters in 
which egg fertilization and development 
are external. Mass spawning occurs when 
many individuals and species release their 
eggs and sperm simultaneously. Mass 
spawning ﬁ  rst gained worldwide attention 
as a result of studies on corals on the 
Great Barrier Reef (GBR), where most 
species are now known to participate in 
Y. Yusuf, M. Noordeloos and J. Oliver
ReefBase
www.reefbase.org
Fig. 1. Coral spawning datasets query using interactive map29 NAGA, WorldFish Center Quarterly  Vol. 26 No. 4 Oct-Dec 2003
articles
mass-spawning events to some extent. 
Elsewhere, many species have been 
observed participating in mass spawning 
events, e.g. in Okinawa, Taiwan, Hong 
Kong, the high latitudes of Australia, the 
Mediterranean Sea, the Gulf of Mexico, 
Bermuda, other parts of the Caribbean, 
the eastern Paciﬁ  c Ocean, Galapagos 
Islands, and Brazil. 
In many areas, spawning is generally 
predictable and highly synchronous among 
colonies and species. It is thought that a 
variety of environmental factors help 
corals to synchronize the timing of 
spawning events. Maturation of gametes 
has been linked with an increase in water 
temperatures in the months prior to 
spawning. The main nights of spawning 
coincide with neap tide periods when 
tidal currents are minimal, increasing the 
chance of fertilization. 
The timing and degree of mass spawning 
within and among coral species varies 
widely among coral communities in 
different locations. Fautin (2002) provides 
some spawning “rules of thumb”:
•  On the GBR, over 140 broadcast 
spawning coral species reproduce 
during annual mass spawning events 
over 4-5 day periods, a few nights 
after the full moon, during spring or 
early summer.
•  In Western Australia, corals at both 
tropical and subtropical latitudes mass 
spawn in the late summer.
•  In southern Japan, mass coral 
spawning occurs on reefs at  Akajima 
Island, although spawning is less 
synchronous, with the main period of 
spawning extending over 2-3 lunar 
months in some species.
•  In the Caribbean, coral spawning 
usually occurs from July to September 
and corals on northern reefs spawn 
earlier than those on southern reefs. 
Spawning is concentrated during 
periods of 2-9 nights after the full 
moon. Some multispeciﬁ  c spawning 
on the same night within a site has 
also been recorded.
Fig. 2. Coral spawning: Favia sp. releasing eggs
•  At Eilat in the northern Red Sea, 
spawning within each species is 
synchronized at particular lunar 
phases each year; however, spawning 
among species is asynchronous and is 
staggered over a four-month period.
•  Extended reproductive seasons with 
less synchronization of spawning 
among coral species have also been 
recorded in Hawaii, the Gulf of 
Mexico and the central and eastern 
Paciﬁ  c.
Source: Fautin, D.G. 2002. Reproduction of 
Cnidaria. Can. J. Zool. 80:1735-1754. 
  
Coral spawning in ReefBase
As a result of recent interest within the 
scientiﬁ  c community in coral spawning, 
ReefBase started compiling spawning 
observations into a standard database. 
This database currently holds information 
on 99 coral spawning observations. This 
dataset is regularly updated and 
expanded, using scientiﬁ  c publications, the 
CoralList email-group, and other sources. 
The Coral Spawning dataset can be 
downloaded from ReefBase’s Download 
Section (http://www.reefbase.org/
download.asp), and can also be 
automatically displayed in ReefBase’s GIS. 
This allows you to view and query coral 
reef datasets using interactive maps (Fig. 
1). In addition, ReefBase’s Photo Gallery 
currently contains 35 photos on coral 
spawning, and the Literature Database 
lists some 100 references related to coral 
spawning.
  
How you can help
If you observe(d) coral spawning (Fig. 2), 
we are keen to hear from you. There are 
several ways in which you can contribute 
to ReefBase and help the wider scientiﬁ  c 
and management community to get a 
better overview of this important 
phenomenon. Spawning observations can 
be sent to us via e-mail, or entered into 
our Spawning Form 
(http://www.reefbase.org/input/
inp_spawning.asp), which will feed directly 
into the ReefBase database. In addition, if 
you have any copyright-free photos and/or 
publications related to coral spawning, you 
can use the Photo Upload and/or Literature 
Upload facilities on the ReefBase website.

Coral spawning information

http://www.worldfishcenter.org/Naga/naga26-4/pdf/naga-26-4-reefbase.pdf

Coral spawning information

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