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 An extensive amount of research has analyzed moon luminance periodicity
and its contribution to lunar spawning synchronicity. Data extracts will
be included below and have been combined into 5 different groups. The
Great Barrier Reef, The Red Sea, The Hawaiian Islands, The Caribbean and
the Authors Captive Reef Ecosystem. 

 - The Great Barrier Reef -

 Research locations on the Great Barrier Reef included Magnetic Island
(19 deg 10 min S) (146 deg 52 min E), Orpheus Island (18 deg 36 min S)
(146 deg 29 min E), Big Broadhurst Reef and Bowden Reef (~19 deg S), Liz-
ard Island (~15 deg S) and Heron Island. Mass synchronous spawning in 
October and November from 1984 to 1987 for 16 species of soft coral (Al-
cyoniidae Family) at Magnetic Island was observed 2 to 5 days following
the full moon. Spawning occurred at Orpheus Island in November and De-
cember (Alino and Coll, 1989). Spawning in 1983 was observed on Big 
Broadhurst, Bowden Reef and Lizard Island to occur 5 to 6 days following 
the seasonal full moon. At Magnetic and Orpheus Island spawning was 3 
to 5 days following the full moon (Babcock et al., 1986). In 1981 mass 
spawning occurred in mid-october and mid-november 5 to 8 days after the
full moon at Magnetic Island. Spawning was observed again in november 4
to 5 days after the full moon. Acroporid and Faviid species were seen to
release spawns from 2000-2330 during the night. Spawns in 1982 were also
seen at Orpheus Island and Bowden Reef in early December from 4 to 5 days 
following the full moon (Harrison et al., 1984). The species Goniastrea
australensis spawned at Heron Island between day 3 and 4 following the
full moon during research conducted from 1977 to 1980. Spawning occurred
from 1600-1800 during neap low tides (Kojis and Quinn, 1981).

 One reason for synchronous lunar spawning was speculated to be the re-
duction in the ability of would-be predators to consume all the repro-
ductive products from the spawning coral colonies (Alino and Coll, 1989).
It appears that the seasonal warming spring water started the maturing 
of gonads in these great barrier reef corals. A large study of 105 spe-
cies found that 87 of them spawned within 3 to 6 nights following the 
seasonal full moon. One mass spawning occurred on the inshore reefs in
october and this was followed by the off shore reefs which spawned in 
november (Babcock et al., 1986).

 - The Red Sea -

 The soft coral Parerythropodium fulvum fulvum was found to have two 
distinct lunar spawning rhythms. Shallow water (3 - 5 m) coral spawned 
between the full moon and last quarter. Deeper reef zone (27 - 30 m)
coral spawned between the new moon and first quarter. The reproductive
period for this	surface brooding egg developer was from the end of june
through the beginning of august (Benayahu and Loya, 1983). The planula 
brooding coral Stylophora pistillata was studied at a latitude of 30 deg 
N in the Gulf of Eilat. Planulae shedding occurred from december through
july during all 8 moon phases. The annual temperature range was 20 C to 
26 C. This same species was found to exhibit year long planulation with 
lunar periodicity at 7.5 deg N in a annual temperature range of 27 C to 
28 C (Rinkevich and Loya, 1979). Spawning on the Red Sea was discovered 
to exhibit some lunar periodicity however spawning seasons, months and 
lunar phases varied. The development of these traits have been attributed
to temporal reproductive isolation. The reproductive season was 3 to 4
months long and spawning occurred generally twice annually for 2 to 6 
nights. Most gonads started development in january and february and actual
spawning releases occurred in may, june, july and august (Shlesinger,

 - The Hawaiian Islands -

 Three species of Acropora were studied on the French Frigate Shoals and
A. valida spawned in 1989 right after a new moon. A. humilis was observed
to spawn during the moons first quarter. A. cytherea in okinawa spawned 1
to 2 days after the late spring full moon. On Johnston Atoll the coral was
seen to spawn 5 to 6 nights after the may 31 full moon in 1988 (Kenyon,

 A study on the coral species Pocillopora damicornis verified that lunar
periodicity was occurring for this monthly planula brooder. Two distinct 
types of P. damicornis were analyzed. Type Y spawned synced to the full
moon while Type B synced to new moon phases. The corals were subjected to
constant full moon luminance, constant new moon luminance and a 15 day
shifted lunar cycle. The corals responded quickly to the shifted cycle 
experiment. The reproductive output was reduced during the constant new
and full moon experiments. The following table combines results from both
coral types.
               |  constant full         shifted          constant new
 larvae        |
 produced      |     15,400              23,100             11,300
 mean planulae |
 settled on    |      7.30                52.00              35.50
 aquaria wall  |
 Type Y was able to sync into the shifted phase in 3 to 4 cycles while
type B could accomplish this shift in 2 to 3 cycles. Type B spawning went
into a unsynced rhythm very quickly in a constant full moon while type Y
held sync for 3 or 4 phases till going unsynced. Both types went into 
very little productive output after only 2 phases of new moon treatment.
Type Y was able to increase an unsynced production in 3 to 4 phases. In
nature type B will reduce its monthly planulae output during heavy cloud
cover periods. Type Y has shown an ability to sync into a new rhythm with-
out an apparent external sync.
 This study concluded that the mechanisms behind these observed phenomenon
in corals (as in most other species) is a mystery. They also noted that
the rather dramatic biological response to changes in the monthly cycle of
night irradiance demonstrates that subtle modulation of the natural photic
environment is an extremely important environmental factor. One explana-
tion for this phenomenon was that a regulatory process in corals involves
the photo chemical control of a substance that influences early gametogen-
esis. Another possibility was that extremely low rates of photosynthesis
by zooxanthellae on moonlit nights might influence metabolism and hence
influence reproduction in corals. Species could posses neurologically
linked photoreceptors that have not yet been described (Jokiel et al.,
 Two species of Pocillopora were also researched in the eastern pacific. 
P. damicornis spawned after the new moon and P. elegans spawned after the
full moon (Glynn et al., 1991).

 A study in Hawaii and Enewetak was performed on 19 species. Coral species
Pocillopora damicornis spawned after a full moon in Hawaii but spawned 
after a new moon at Enewetak. In Australia this species only planulated 
after the new moon from december to april and after the full moon from 
july to august. In Palau the coral was a new moon spawner. The following
table lists percentage spawning for some species during the 4 lunar phases
(Stimson, 1978).
    species         |new (1-7)|first (8-14)|full (15-12)|last (22-28)
 Pocillopora jun-jul|   55 %  |    29 %    |     1 %    |     0 %    
  verrucosa    jan  |   16 %  |    53 %    |     0 %    |     0 %
 Pocillopora jun-jul|   65 %  |    12 %    |     0 %    |    38 %
  damicornis   jan  |   57 %  |   100 %    |     0 %    |     8 %
 Pocillopora jun-jul|   60 %  |     5 %    |     0 %    |     0 %
  elegans      jan  |    0 %  |    40 %    |     0 %    |     0 %
 Seriatopora jun-jul|   54 %  |    43 %    |    27 %    |     0 %
  hystrix      jan  |    0 %  |    ---     |     0 %    |    13 %
 Acropora    jun-jul|   40 %  |     0 %    |     0 %    |     0 %
  humilis      jan  |    0 %  |     0 %    |     0 %    |     0 %
 Acropora    jun-jul|    0 %  |     8 %    |     0 %    |     0 %
  striata      jan  |   29 %  |    33 %    |     0 %    |     0 %
 Acropora    jun-jul|   12 %  |    20 %    |     0 %    |     0 %
  corymbosa    jan  |    0 %  |     0 %    |     0 %    |     0 %

 - The Caribbean -

 In the shallow waters of the Atlantic coast of Panama, 11 species of
scleractinian coral were studied at a latitude of 9 deg N. Spawning
periodicity for 7 broadcast corals was from august to september which
happened to be a period of declining temperatures. Annual sea tempera-
tures vary from 26.5 C to 29 C and initiation of gametogenesis might be
caused by rising temperature in spring. The remaining studied species
were year long planula brooding spawners. Of the four planulae brooders
only Favia fragum showed lunar periodicity in release rhythm. Planula 
size for F. fragum exhibited a lunar development rhythm which is listed 
below (Soong, 1991).
         lunar day  |   24   25   26   30   5   8   10
         size in mm |  .55  .60  .67  .72  .81 .83 .86

 The coral species Favia fragum, a year long planulae brooder, was stud-
ied to determine if lunar periodicity existed in development of sperma-
tozoa, ovaries and embryo. Lunar periodicity was found during oogenesis
by determining that maximum size was reached from 8 to 18 days following
the new moon. It appears that several months are required for oocytes to
attain maximum size and only a few are fertilized every month. Spermato-
genesis was also found to have lunar periodicity by developing tails from
day 10 to 18. Embryogenesis first started from day 16 to 17 with the ap-
pearance of embryos which developed into brooded planulae. Peak release 
of fully developed planulae occurred from day 9 to 11. The timing of ovu-
lation and spawning events were more closely synchronized with the lunar
cycle than the timing of planulation. Ovulation occurs over at most 2 to
3 day period, while planulation occurs over more than a week. This study
suggested that the lunar forces are acting to synchronize the spawning
event and that the planulae begin to dribble out about 3 weeks later as
they mature (Szmant-Froelich et al., 1985).

 A study of Caribbean corals was performed to determine lunar periodi-
city. Most corals observed spawned in the July to September period.
Diploria strigosa was observed spawning 7 nights following the July/
August 1985 full moon. Preparation for spawning for Acropora cervicornis
on night 6 after the August 1984 full moon and 7 to 8 days after the 
July/August 1985 full moon. Several colonies of Montastrea annularis
spawned in the laboratory 8 days after the September 1984 full moon.
The D. strigosa released large bundles 2-4 mm in diameter of gametes by
individual polyps at around 2100 h. Mycetophyllia ferox brooded planula
only during the winter season (January to April). Favia fragum displayed
embryogenic cycles all year long. This study demonstrates that Caribbean
Reef corals do have well-defined seasonal patterns of sexual reproduction
(Szmant, 1986).

 The caribbean broadcast spawning reef corals Montastrea annularis and 
M. cavernosa were studied at Puerto Rico. M. annularis is hermaphroditic
while M. cavernosa is gonochoric. Speculation was made that planulating
coral are opportunistic and short lived corals, while broadcast spawners
are longer lived. Oogenesis in M. annularis begins in early summer and is
completed in less than 4 months. While in M. cavernosa oogenesis occurs
throughout most of the year. The spermatogenic period of M. annularis is 
also shorter than M. cavernosa. Both species spawned 1 week after the full
moon in august. Annual temperature range is 3 to 4 C. Spawning in Puerto
Rico occurs in the warmest months of year while the photoperiod is de-
creasing. Spawning might be uniform from Bermuda to Panama which could
contradict the Great Barrier Reef latitudinal spawning variations (Szmant,

 - The Authors Captive Reef Ecosystem -

 A lunar time scale experiment was conducted on the authors reef and the
full moon periodicity was shortened to a 15 day cycle instead of the nor-
mal 29.5 days. This experiment attempted to produce a synchronous mass 
spawn within a 3 month test period but was not successful. While this ex-
periment was running an annual broadcast egg spawner released eggs and 2 
brooders released planulae bundles. The egg broadcaster was a branching
Euphyllia ancora coral that released eggs after an artificial new moon on
July 8 1992. Planulae bundles of green and brown color were also released
during this experiment. The events are listed below.

  June 6 1992 new moon
                           June 9  green planulae bundle released
                           June 11 brown planulae bundle released
  June 14 1992 full moon   
  June 21 1992 new moon
  June 29 1992 full moon
  July 6 1992 new moon     July 8  approximately 100 eggs broadcast
                           July 9  approximately 200 eggs broadcast
                           July 9  green planulae bundle released
                           July 10 approximately 1500 eggs broadcast
                           July 11 approximately 50 eggs broadcast
                           July 11 brown planulae bundle released
  July 14 1992 full moon 
  July 21 1992 new moon    July 21 approximately 250 eggs broadcast
                           July 22 approximately 1000 eggs broadcast
                           July 23 approximately 250 eggs broadcast
                           July 24 approximately 200 eggs broadcast
  July 25 1992 constant full moon interruption till august 4. 
  August 5 1992 new moon   August 9 approximately 100 eggs broadcast.

 The above recordings illustrate that the monthly planulae brooders were
probably not able to produce mature planulae in half normal time. The 
annual egg broadcaster released eggs after the new moon on July 6 and 15
days later after the July 21 new moon. This demonstrates that once the 
eggs are mature the spawning release will sync into the lunar phase even 
if this phase is twice as fast. This experiment shows the importance of
using a rhythmic moon luminance in the spawning induction of captive co-
rals. Since most spawns occur following the full moon and new moon, it 
appears that the actual triggers may be the lowering of luminance inten-
sity from full and the increasing luminance from new. The authors reef  
ecosystem is currently synced into a natural 29.5 day lunar rhythm.
 Moon Rise and Set Times
 This parameter represents the rise and set time of the moon for any spe-
cific day of the monthly cycle. Calculating rise and set times for exact
geographical reef locations requires algorithmic computer power for accu-
racy, however some published marine tables are available. Astronomical 
software programs could be combined with computer control to automatically
raise and lower the proper moon luminance at specific calculated times. 
Integrating a moon control system can be very beneficial for inducing sp-
awning but fortunately less complicated methods are possible. The authors
moon control system requires the manual linear setting of luminance values
which are based on average total photons received per night. This has sti-
mulated Euphyllia ancora, Trachyphyllia geoffroyi, Gorgonian sp., Turbin-
aria turbinata, Actinodiscus sp. and other corals to naturally spawn via
planulae or coral egg releases. The table below lists the authors monthly
linear moon luminance values for an entire cycle. Note - full moon inten-
sity is approximately half twilight intensity.
day  | 1   2   3   4   5   6   7   8   9   10   11   12   13   14   15  16
value|.00 .01 .02 .04 .07 .11 .16 .22 .28 .36  .44  .54  .64  .74  .86 1.0
phase|new                            first                            full
day  | 17  18   19   20   21   22   23   24   25   26   27   28   29   30
value|.86 .74  .64  .54  .44  .36  .28  .22  .16  .11  .07  .04  .02  .01
phase|                            last 
 Interruptions of moonlight regularly occur due to cloud weather patterns
which vary nightly and hourly. This has led scientists to speculate that
lunar rise and set times could be significant in the development of sync-
hronous monthly spawning rhythms (Oliver, 1992). This potential ability to
sync with rise and set times might find substantiation in a scientific
study performed on Pocillopora damicornis coral. The coral was researched 
at Enewetak Marshall Islands (11 deg 26 min N) (162 deg 24 min E) and Kan-
eoke Bay Hawaii (21 deg 60 min N) (157 deg 47 min W). Three distinct lunar
rhythms were discovered and determination if these were due to geographic
phenomena or isolated phase shifting was attempted. Planula releases that
occurred in outdoor aquaria stayed in sync with the natural undisturbed
specimens on the reef. The species in Enewetak released planula following
the new moon with peak releases occurring seven days after full. In Kan-
eoke Bay two distinct planula lunar release periods were found. One group
released between the full moon phase and third quarter, while the second
group preferred to release between the first quarter and the full moon.
The mean water temperature in hawaii was 25.0 C (77.0 F) with an annual
range of 7.7 C and the study sites were in shallow water. A mean temper-
ature of 27.9 C (82.2 F) with an annual range of 4.8 C occurred in the
deeper waters at Enewetak. One hypothesis for the shifted lunar spawning
phase was the possibility that geographically separated populations thr-
ough natural selection had modified their timing of peak planula release
to coincide with optimum local environmental conditions. A second hypo-
thesis was concerned with the possibility that these coral were actually
composed of three distinct species of Pocillopora. The ability to synch-
ronize planulae release on any phase of the moon was certainly demonstra-
ted (Richmond and Jokiel, 1984).
 Water Temperature
 This parameter represents the average daily water temperature and usually
varies in a seasonal rhythm. Daily temperature fluctuations in a captive
reef ecosystem should be kept to a minimum. Water on a natural reef is
warmer during the local summer period and cooler during the local winter
period and some reef locations experience very large annual temperature
extremes. These variations in temperature were researched in three scien-
tific studies and data from this research is listed below. Note - Some
values were interpreted from graphs.

 Annual temperatures on Curacao Netherlands Antilles (12 deg 30 min N).
   (Van Moorsel, G.W.N.M., 1983).
        1979  jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
          C   26.6 26.4 26.3 26.5 26.8 28.1 27.6 27.7 28.6 28.5 28.7 27.4

        1980  jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
          C   26.8 26.7 25.4 26.5 27.4 27.0 26.8 27.8 28.5 29.0 28.2 27.2

        1981  jan  feb  mar  apr 
          C   27.2 27.0 26.6 27.5 

 Maximum and minimum temperature examples for the eastern side of Canga-
luyan Island, Pangasinan, Philippines (16 deg 22 min N) (120 deg 0 min E)
(Yap et al., 1992).
    Highest maximum daily temperature 33 C (91.4 F) jul-oct 1983
    Lowest maximum daily temperature 29 C (84.2 F) jan-feb 1984
    Highest minimum daily temperature 31 C (87.8 F) apr-jun 1984
    Lowest minimum daily temperature 24 C (75.2 F) dec 83 - jan 1984
  Maximum temperatures
     1983  July/Apr   Sep/Oct   Dec/Jan   Feb/Mar   Apr/May  1984
             33         33        29.7     31.6       32       C
  Minimum temperatures
     1983  July/Apr   Sep/Oct   Dec/Jan   Feb/Mar   Apr/May  1984
             28         26.8      23.9     25.8       31       C

 Barbados seasonal temperature extremes, 26.2 C(79.2 F) - 29.5 C(85.1 F)
(13 deg 10 min N) (Tomascik and Sander, 1985).

 When seasonal temperature variations have wide extremes, corals appear
to spawn within certain thermal parameters. Temperatures coinciding with
tropical coral spawning were researched and data extracts from four of
these studies is listed below.

 Gonad maturation of Goniastrea australenis at Heron Island on the Great
Barrier Reef may be influenced by the spring temperature rise beginning
in september. Final ripening occurred when a minimum temperature of ap-
proximately 23 C (73.4 F) to 24 C (75.2 F) was reached. At nearby Lord 
Howe Island the rapid spring temperature rise begins in november and the
23 to 24 C gradient is not reached until January. This could explain why 
spawning of this species occurs 2 months later at Lord Howe Island (Kojis
and Quinn, 1981).

 The coral Pocillopora damicornis was studied in Hawaii and the best re-
productive temperature was found to be 26 to 27 C (78.8 to 80.6 F). The 
maximum reproduction rate occurred within 1 degree C of 26.5 C. The coral
was able to maintain a high growth rate in the 24 to 29 degree C range,
with rates changing by less than 10 % with a 1 degree C difference in tem-
perature. The high reproductive rate changed drastically with a 1 degree
difference in the temperature range of 26 - 27 degree C. Summer tempera-
ture was always above 26 C (Jokiel and Guinther, 1978a).

 Sexual reproductive spawning in Hawaii of various Acropora sp. occurred
at a temperature of 29.5 degrees Centigrade (85.1 F)(Kenyon, 1992).
 The Great Barrier Reef undergoes a rapid rise in temperature which occurs
in the local spring from august to september. Mass spawnings happen from 
mid-october to early december. The possible importance of temperature in
determining timing of the spawning season is supported by the differences
in the month of spawning at the inshore and offshore reefs. On 1982 at Ma-
gnetic Island, spawning happened during early november while spawning at
Big Broadhurst Reef, Orpheus Island occurred one month later in early de-
cember. The shallow water at Magnetic Island warms faster and gonads ma-
ture quicker. The following charts list temperature data from these sites.
(Babcock et al., 1986).
  Palm Island  jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
   1979-1984   30.3 30.6 30.2 28.8 27.1 24.8 23.0 23.4 25.1 27.1 28.8 29.2 
   2-5m depth   spawning occurred in november at 28.3 C
  Magnetic                                             25.1 28.2 29.6
     Island     spawning occurred in october at 27.4 C 
                    jan  apr  sep  oct  nov
            1980    21.5 22.0 24.0 26.7 28.0   spawning 27.3 C
            1981    22.0 23.8 24.6 24.5 28.0   spawning 26.5 and 29.0 C
            1982    21.0 21.5 22.2 24.5 27.0   spawning 27 C
            1983    21.3 21.5 24.0 28.0 29.0   spawning 28.4 C

 Temperatures and photoperiods follow annual patterns that vary relative 
to latitudinal location. These geo-indexed parameters might be the con-
trolling factors in spawning pattern variances. Latitudinal seasonal va-
riations have been studied and data from three of these studies was ex-
tracted and listed below.

 The following chart compares annual temperature variations to latitudinal
locations (Richmond and Hunter, 1990).
 |parameter       |Central|Caribbean|Hawaii|Red Sea|Okinawa|Great Barrier|
 |description     |Pacific|         |      |       |       |Reef-Magnetic|
 |                | Guam  | Barbados| Oahu | Eilat |       | Island      |
 |annual variation|       |         |      |       |       |             |
 |in sea water    |  2.2  |   3.2   | 4.0  |  6.0  |  9.8  |   12.0      |
 |temperature     |       |         |      |       |       |             |
 |percentage of   |       |         |      |       |       |             |
 |coral spawning  |  18%  |   26%   |  29% |  20%  |  65%  |    88%      |
 |in same month   |       |         |      |       |       |             |
 |and lunar phase |       |         |      |       |       |             |
 |latitude degrees|13 deg | 13 deg  |21 deg|30 deg |26 deg |   19 deg    |
 |latitude minutes|30 min | 10 min  |30 min|00 min |30 min |   00 min    |
 |depth of site   |> 10 m | > 10 m  |> 10 m|> 10 m |> 10 m | *  < 10 m   |
   Temperature variation in the above chart is in degrees centigrade. De-
  gree of synchrony among species may be related to sea water temperature
  ranges in each region and the trend is for decreasing synchrony as the 
  annual variations in temperature get smaller. This correlates with ti-
  ghter interspecific synchrony with increased seasonal temperature range.
  This could establish an order of importance for the parameters causing
  synchronicity in mass spawning to be: temperature (seasonal cue), photo-
  period (stimulate photosynthesis) and moon luminance (monthly sync).

 The coral Pocillopora damicornis was studied at Rottnest Island near
Western Australia which is the southern limit of its distribution. The
findings from this study were compared to studies performed on this sp-
ecies at other geographical locations. The seasonality in planulation 
is primarily mediated by variations in sea temperature. The local varia-
tion in sea temperatures were greater than 10 degrees C. Planulation
only occurred at maximum water temperature of 25 to 26 C. This species
in Hawaii was found to have a year round planulation with optimum de-
velopment of planulae occurring at 26 to 27 degrees C. The temperature  
annual range at the Hawaii location was 7.7 degrees C. On Lizard Island
of the Great Barrier Reef the annual temperature range is 4 degrees C,
which provides a less marked seasonal variation in temperature. A sub-
stantial seasonal component was found in the abundance of planulae, due
to the planulation rate being minimum at minimum temperature ranges. At
Enewetak on the Marshall Islands seasonal temperature varies only 4.8
degrees C. Year round planulation occurs with a fecundity rate doubled
during summer as compared to winter. This means that environmental pa-
rameters don't fully explain the latitudinal variation in planulation
for this species, due to the Lizard Island findings. At non-optimum tem-
peratures the period of gametogenesis may be increased, planulation may
shift or production can be ceased and reabsorption of gametes may ensue
(Stoddart and Black, 1985).
 The coral Acropora palifera, a planulae producer, was studied at three
different locations. The latitudinal coordinates of the locations were
all south of the equator and are listed below (Kojis, 1986b).
 Lizard Island  Great Barrier Reef  Lat 14 degrees 40 minutes 
 Salamaua/Busama near Lae, Papua New Guinea Lat 7 degrees 4 minutes 
 Heron Island Great Barrier Reef Lat 23 degrees 27 minutes (Kojis, 1986a)
 The intent of the study was to determine how sea temperatures which vary
inversely with latitude, affect the spawning procedures of this coral. 
The mean temperature and annual range are listed below.
  measurement    |   Salamaua   |   Lizard Island   |   Heron Island   |
  mean surface   |              |                   |                  |
  temperature    |    29.5 C    |      26.5 C       |     24.5 C       |
  annual range of|              |                   |                  |
  monthly mean   |     3.5 C    |        5 C        |       6 C        |
  water temps    |              |                   |                  |
  latitude       | 7 deg 4 min S| 14 deg 40 min S   | 23 deg 27 min S  |
                 | low latitude | mid latitude      | high latitude    |
  breeding       |  year round  |    year round     |  once in spring  |
                 |  monthly     |    monthly        |  yearly          |
  fecund percent |  50 % shift  |    50 % shift     |      100 %       |
  minimum temp   |    > 24  C   |                   | breed at 24 C Two|
                 |              |                   | months before max|
  monthly temp|jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
 Heron island |27.2 27.2 27.2 26.0 24.5 22.8 22.2 21.8 21.7 23.2 25.0 26.7
 Lizard Island|29.1 29.0 28.9 27.2 26.0 25.5 24.1 24.5 25.0 25.5 26.8 28.0
 Salamaua     |31.2 31.9 30.5 30.8 27.7 29.6 28.4 28.6 28.0 28.7 31.1 31.0
  note - Heron island temps averaged over 12 years. 1966-1977
         Lizard island temps averaged over 9 years. 1974-1982
         (Kojis, 1986b)
 The monthly temperature table shows that the coolest months were july to
september. The rising temperature gradient occurred from october to decem-
ber. Latitudes from 23 to 14 degrees have sea temperature conditions that
vary annually and this might have caused local marine species to develop
distinctive breeding seasons. Some species do not follow this pattern and
this could be due to species-specific breeding temperature requirements. 
The following hypothesis was supported by the findings of this study. 
"Seasonal variations in sea temperature caused seasonal breeding in marine
animals. The length of the breeding season of a species will be longer in
lower latitudes than in higher ones and that where annual temperature con-
ditions are nearly unvarying, breeding will be year round" (Kojis, 1986b).
 A new hypothesis was devised in the study. In high latitude regions the 
marine species evolve a history strategy that limits the amount of energy
they allocate to reproduction, so that more energy can be allocated to
growth. The single annual reproductive cycle and accompanying production 
of fewer planulae, along with the larger size of colonies at Salamaua ap-
pears to support this supposition. The justification for additional allo-
cation of resources to growth is due to the lower temperature and shorter
photoperiod which slows growth, development and gamete maturation in the
winter season. The planulae on Heron Island were retained for 4.5 months
while those at Salamaua which were fewer and smaller were retained for 2.5
months. This meant that less effort was put into reproduction by the Sala-
maua corals on average but more spawns occurred year round. Large seasonal
temperature extremes might influence the timing of reproduction. If the
temperature patterns are small or unstable, photoperiod might become the
main factor for establishing the timing of reproduction (Kojis, 1986b).

 The average seasonal temperature periodicity reported in the preceding 
scientific studies was 76.8 F to 85.8 F or 24.9 C to 29.9 C. Average sp-
awning occurrence range was 77 F to 78.8 F or 25 C to 26 C, however three
single species studied reported average spawning temperatures of 83.1 F or 
28.4 C. The average mean yearly temperature for the three latitudes of 7,
14 and 23 degrees was 80.3 F or 26.8 C. Spawning induction should occur in
a captive aquaria in the 77 F (25 C) to 79 F (26 C) degree range, however
the peak summer temperature could be as high as 79 F (26.1 C) to 81 F (27.
2 C). The suggested maximum annual rhythm is 75 F (23.9 C) to 80 F (26.7
C) for a reef which is operating exceptionally well. Higher temperatures 
might be required for certain geographically located species which only
spawn at temperatures exceeding 80 F (26.7 C). The latitudinal location
and depth specifications for a naturally developed specimen is very impor-
tant for ecosystem duplication. If a mass synchronous spawning event is
desired than the wide temperature rhythms which occur at high latitudes
should be duplicated. Monthly spawning with less synchronicity requires a
narrow rhythm with a higher temperature average that is equivalent to the
environmental specifications which occur at lower latitudes. Please exer-
cise caution when using reef ecosystem temperatures that exceed 79 F or
26 C.
 Salinity Trends
 This parameter represents local salinity trends which occur in certain 
natural reef locations. An example of these trends was recorded during a
scientific study conducted on Barbados in the West Indies. The findings 
will be listed below.

   Monthly Salinity and Temperature Rhythms. Salinity in ppt. Temp in C.
 |start 1982 |June July Aug  Sep  Oct  Nov  Dec  Jan  Feb  Mar  Apr  May |
 |location 1 |                                                           |
 |salinity   |29.3 29.9 30.4 32.0 32.0 32.2 33.7 33.3 33.1 32.4 31.8 30.7|
 |temperature|28.3 28.5 28.7 29.3 29.9 30.2 28.8 27.9 28.1 27.3 27.3 28.3|
 |location 2 |                                                           |
 |salinity   |31.2 32.1 31.3 32.2 31.2 34.5 34.2 35.2 35.5 34.1 33.7 33.3|
 |temperature|27.6 27.7 28.6 28.0 28.5 29.2 28.8 27.8 27.2 26.2 26.3 27.0|
 |location 3 |                                                           |
 |salinity   |32.2 31.8 30.9 32.2 31.8 34.5 34.2 35.2 35.4 34.2 33.5 33.0|
 |temperature|27.6 27.6 28.5 27.7 28.5 29.2 28.8 27.8 27.3 26.3 26.4 27.0|
   Highest temperatures occurred from september through november. They
  then sloped downward until the march through april cold period. The
  highest salinities occurred around january and then the value declin-
  ed until june and july.
   All three locations were studied and the average number of male and 
  female gonads per 0.25 cm squared of Porites porites tissue represent- 
  ed the productive activity or Gonad Index. The peak months of activity
  occurred from november through january. The following table column val-
  ues are defined as follows. Gonad Index as described above. Temp in de-
  grees Centigrade. Salinity in ppt. SPM (suspended particulate matter) 
  in mg per liter. Chla (chlorophyll a) in mg per meter cubed. PEN (per-
  centage of surface illumination) in percentage (Tomascik and Sander, 
 |                  |Gonad Index   Temp  Salinity   SPM   Chla     PEN   |
 |location 1        |                                                    | 
 |average value     |   5.48      28.56    32.3     7.32  0.895   28.82  |
 |standard deviation|   5.22       1.11     1.7     2.86  0.406   11.84  |
 |sample size       |   137        57       56       46    46      28    |
 |location 2        |                                                    | 
 |average value     |   6.26      27.89    33.5     5.94  0.799   34.52  |
 |standard deviation|   6.65       0.94     1.1     3.41  0.470    7.32  |
 |sample size       |   119        57       54       44    46      28    |
 |location 3        |                                                    | 
 |average value     |   8.85      27.82    33.4     5.21  0.546   40.45  |
 |standard deviation|   8.51       0.91     1.2     3.29  0.270    8.43  |
 |sample size       |   110        57       56       44    46      28    |
     The Gonad Index increase from location 1 to 2 was 12.5 % and from 
    location 1 to 3 was 38.1 %. This difference between the three sites
    might be due to genetic variability or the different environmental 
    parameters recorded (Tomascik and Sander, 1987).

 Annual synchronous spawning events which only occur during a few days are
occasionally subjected to the environmental parameter extremes which can
occur in a natural reef ecosystem. An example affecting buoyant propagules
from epidemic spawning corals occurred at Magnetic Island in November 1981.
A heavy rain squall coincided with the spawning and propagules on the sur-
face were probably destroyed by reduced salinity. This negated the repro-
ductive effort of these coral for an entire year (Harrison et al., 1984).
 One scientific study recorded annual rainfall and temperature at four
locations in the central american region. Costa Rica (lat 8 deg 43 min N)
(long 83 deg 52 min), Panama Gulf of Chirigui (lat 7 deg 49 min N) (long
81 deg 45 min), Panama Gulf of Panama (lat 8 deg 38 min N) (long 79 deg 
4 min) and Galapagos Island (lat 0 deg 35 min S) (long 90 deg 17 min). 
In the table that follows temp is in degrees centigrade and ppt is pre-
cipitation in parts per thousand. Note - values were interpreted from
graphs (Glynn et al., 1991).
 location   |jan  feb  mar  apr  may  jun  jul  aug  sep  oct  nov  dec
 Costa Rica |
    ppt     | 0    0    5    15  115  220  215  190  240  245  100   15
    temp    |28.2 28.5 28.8 29.1 28.7 28.5 28.5 28.4 28.3 28.0 27.9 28.0
 of Chirigui|
    ppt     | 30   35   50  100  205  250  210  290  295  415  250  105
    temp    |28.6 28.7 29.0 29.0 28.7 28.4 28.4 28.5 28.2 27.9 28.0 28.2
 of Panama  |
    ppt     | 25   10    5   65  220  190  195  205  200  305  280  130
    temp    |26.2 24.9 24.2 25.8 28.4 29.0 28.8 28.9 29.0 28.8 28.5 28.2
 Galapagos  |
  Island    |
    ppt     | 35   15   60   60   50   45   15   5    5    7    7    30
    temp    |24.7 25.1 25.2 25.3 24.4 23.2 22.8 21.7 22.0 22.3 22.9 23.4
Some natural reef locations do experience seasonally rhythmic salinity 
variations which are primarily due to freshwater rainfall which occurs
during the local rainy seasons. The value of this salinity parameter for
the induction of spawning in a captive reef ecosystem has yet to be deter-
 Local Hydrodynamics
 This parameter represents local current strengths and how they induce
morphological changes in coral growth. These ecomorphs might have rele-
vance in the development of spawning induction procedures. An experiment
conducted in Hawaii was run to determine the effects water motion vari-
ability would have on different types of stony corals. Three coral species
were utilized with each reaching maximum abundance in specific water cur-
rent environments. Pocillopora meandrina (high wave energy), P. damicor-
nis (L.) (semiprotected reefs) and Montipora verrucosa (Lamarck) (calm 
environments). The results from this experiment will be summarized here
for analysis by reef breeders who are experimenting with water current 
 |                           |  water motion measured (diffusion factor)  |
 | Environment               |      n         mean  +-S.D.       Range    |
 |Montipora verrucosa zone   |     61         2.4 +- 1.19      1.5 - 6.7  | 
 |Pocillopora damicornis zone|     34         4.3 +- 1.35      2.3 - 6.6  | 
 |Pocillopora meandrina zone |     30        15.0 +- 6.69      4.9 - 27.1 | 
   Results of Laboratory Water Motion Study (Jokiel, 1978b)
 | parameter measured               |   relative water motion treatment   |
 |                                  |   low(L)    medium(M)     high(H)   |
 |water motion energy transfer rate |     0         0.05         0.33     |
 | (agitator horsepower in aquarium)|                                     | 
 |mean temperature. n=41. (C+-S.D.) | 24.0 +-0.8  24.0 +-0.8   24.3 +-0.9 |
 |mean measured water motion n=15   |  1.7 +-0.3   5.4 +-1.9    7.4 +-2.3 |
 | (diffusion factor +- S.D.)       |                                     |
 |median measured water motion n=15 |    1.7         4.7          6.6     |
 | (diffusion factor)               |                                     |
 |coral reproduction (new colonies  |     13         178          237     |
 |                    per aquarium) |                                     | 
 |median size of new colonies       |     1           2            3      |
 |  (number of polyps)              |                                     |
 |median linear growth of colonies  |                                     | 
 |    Pocillopora meandrina  (mm)   |     0          1.1          1.3     |
 |    Pocillopora damicornis (mm)   |    0.5         1.8          2.8     |
 |    Montipora verrucosa    (mm)   |    2.9         3.5          4.4     |
 |mortality as estimated total      |                                     |
 | percentage of tissue loss        |                                     |
 |    Pocillopora meandrina  (mm)   |    40           5            5      |
 |    Pocillopora damicornis (mm)   |     0           0           15      |
 |    Montipora verrucosa    (mm)   |     0           0            0      |
   The calm water coral M. verrucosa achieved a high growth rate in low
  water motion treatment and continued to benefit from increased water
  current. The study did suggest that a certain saturation level exists
  for each particular species that is relative to each specimens prior
  environmental growth exposure. The moderate water coral P. damicornis
  did achieve better growth with stronger water motion but a saturation
  point does exist where growth rate will slow until damage results to
  coral tissue from storm type currents. The turbulent water coral P.
  meandrina probably has a growth rate which peaks at currents twice as 
  high as was simulated in the experiment (Jokiel, 1978b).

 Corals undergo morphological adaptations to differing hydrodynamic envi-
ronments. An example would be the P. meandrina from the study above which
has developed skeletal projections called verrucae which provide a drag on
the water and slow the current flow near the coral surface tissue. These
adaptations were observed for two species of Acropora coral which were lo-
cated at Heron Island Reef in the Great Barrier reef. Five distinct forms
or "ecomorphs" were verified for the hermatypic planulae brooding corals
A. cuneata and A. palifera. The names used to describe these ecomorphs,
(inner reef flat, outer reef flat, crest, slope and lagoon), were derived
from the corals dominate geographical domain (Kojis, 1986a). Coral branch
thickness may also be related to local hydrodynamic environmental parame-
ters. Thick branched specimens which are transferred from strong current
to calm current, experience a high initial mortality rate but will even-
tually grow thinner branches. The initial mortality rate could be attri-
buted to respiratory shock due to a skeletal growth which is not efficien-
tly designed for calm water environments. When thinner branched corals 
are transferred to strong current, thicker branches grow in response to
current divergence (Jokiel, 1978b). Some species of coral have the ability 
to survive and propagate in areas that inhibit normal growth rates. Asex-
ual reproductive processes are the dominate modes used to propagate these
coral species in areas which are environmentally marginal for growth. High
wave energy is one example of an inhibiting parameter (Richmond and Hunter,
1990). Reef currents with velocities of 4 to 5 cm per second, might be
strong enough to passively disperse propagules released from polyp ball
methods of reproduction (Sammarco, 1982).
 Many captive reef engineers are utilizing wave motion generators to pro-
vide a pulsating or rhythmic motion to their reef. This improves the oper-
ation of the corals respiratory system and will keep ecosystem water flow-
ing around the coral. This current will promote the transfer of nutrients,
waste products and dissolved gases between the coral and water interface.
As long as an increased water flow is under the saturation point for a 
particular coral, the respiration will be accelerated contributing to he-
althness and enhancing the ability to develop gametes. The utilization of
this parameter in a captive reef ecosystem can become extremely complex
when individual specimen morphological adaptation requirements are factor-
ed into the system setup. Active water flow needs to exist in any captive
system but the saturation point and specific demands of each coral should
be considered when locating each specimen within the ecosystem. Further
research is required for determination of the value of water current para-
meters as well as wave generated rhythmicity for the induction of spawning
in a captive reef ecosystem. The author has recently upgraded his 180 gal-
lon reef with elevated pvc matrixes which have 1200-2000 liters per hour
submersible water pumps forcing current through holes drilled strategic-
ally in the matrix.
 Local Tidal Variations
 This parameter represents tidewater level changes and associated current
movements. The Great Barrier Reef synchronous mass spawns occur during
neap tides which begin after the full and new moons and continue until 
the third and first quarter moons respectively. An extended slack current
period results from the relative small difference in high and low tidal
water heights. One reason for this spawning evolutionary trait might be
the increased fertilization potential for released gametes (Alino and Coll,
1989)(Babcock et al., 1986)(Kojis and Quinn, 1981). Coral egg or planulae
sexual spawns have been observed in the authors reef during slack current
periods (Trachyphyllia geoffroyi) and high current periods (Euphyllia 
ancora, Gorgonian sp., Turbinaria turbinata and Actinodiscus sp.). When
these occurrences are considered along with other aquaria spawning reports,
the deduction that tidal current rhythms might be coincidental or ancill-
ary to spawning synchronicity, gains substantiation.
 Further evidence against tidal factors influencing synchronous spawning
was documented in an experiment which utilized Pocillopora damicornis co-
ral specimens. Planulae release from this coral in a captive aquaria with-
out tidal influences, stayed in periodicity with field specimens. The rhy-
thmic patterns in the aquaria were more regular and intense than the field
corals due to the more moderate physical environment which existed in the
laboratory. A severe rainstorm on 14 December 1980 killed exposed corals
and caused slightly submerged coral to experience low salinity. This re-
sulted in the continual aborting of developing planulae and a low rate of
reproduction to occur for several months in the field specimens. The lab-
oratory coral ecosystem was cycled with sea water collected from deeper
regions and spawning periodicity was not adversely affected. These corals
also received normal sun and moon luminance and after 16 months the lab-
oratory corals continued to reproduce synchronously with the reef-flat
corals. This experiment probably eliminated futher consideration of tide-
related physical effects on monthly synchronous spawning (Jokiel et al.,
 Fluctuations in Reef Chemistry
 These parameters represent chemical measurements that many captive reef
owners perform routinely. Variances can occur hourly, daily or weekly and
are kept within an established acceptable range. The importance that any 
annual rhythmic parameter variance would have for the induction of coral 
spawning has yet to be determined. They are listed here for completeness
in environment parameter research. Dissolved Oxygen, Dissolved Carbon Di-
oxide, Alkalinity and Hardness, Carbonate Hardness, PH, Redox Potential
and Calcium Concentration. These values might not require annual rhythmic
variance and it would be practical to experiment with the more relevant
parameters discussed previously. Please consult reef aquaria literature
for suggested acceptable levels and ranges for these chemical parameters.
 Alternate Strategy for Applying Environmental Rhythmicity
 Rhythmicity in moon phase luminance appears to be the most important en-
vironmental monthly spawning synchronizer. The natural 29.5 day periodi-
city for this parameter should be artificially simulated in captive reef
ecosystems. The main annual spawning season inducer appears to be temper-
ature variances. As the annual variation increases, the spawning season
will shorten for monthly brooding species whose minimum gonad development
temperatures are not attained. One methodology for inducing spawning en-
tails keeping the annual temperature constant and above the minimum gonad
maturation range. This would prevent the annual egg broadcasters from re-
leasing eggs synchronously on the same lunar cycle and the normal spawning 
month should occur annually due to gonad maturation development require-
ments. Monthly brooders will start to release planulae based on the lunar
periodicity of the ecosystem. Brooding fecundity might be increased if
the photoperiod is kept at a summer length for the entire year. The reef
breeder should employ a different strategy to stimulate spawning which
only occurs during a brief annual period. The utilization of photoperiod
periodicity might be combined with annual temperature variances for the
development of this mass spawning event. The resulting pollution from such
an event should be considered before an attempt is made.
Tropical Coral Reef Environment Rhythmicity and
 Techniques for Inducing Captive Coral Spawning
    October 1992 
Author - Steve Tyree [Reef Breeder and Computer Support Specialist]
Literature Cited

Alino P.M. and J.C. Coll (1989): Observations of the Synchronized Mass 
    Spawning and Postsettlement Activity of Octocorals on the Great Barr-
    ier Reef, Australia: Biological Aspects.  Bull. Mar. Sci. 45:697-707

Babcock R.C., G.D. Bull, P.L. Harrison, A.J. Heyward, J.K. Oliver, C.C.
    Wallace and B.L. Willis (1986): Synchronous spawnings of 105 Sclerac-
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Benayahu Y. and Y. Loya (1983): Surface Brooding in the Red Sea Soft Coral
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Glynn P. W., N. J. Gassman, C. M. Eakin, J. Cortes, D.B. Smith and H. M.
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Harrison P. L., R. C. Babcock, G. D. Bull, J. K. Oliver, C. C. Wallace 
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    ence, N. Y. 223:1186-1189

Jokiel P. L. and E. B. Guinther (1978a): Effects of temperature on repro-
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Jokiel P. L. (1978b): Effects of water motion on reef corals. J. exp.
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Jokiel P. L., R. Y. Ito and P.M. Liu (1985): Night irradiance and sync-
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Kenyon J. C. (1992): Sexual reproduction in Hawaiian Acropora. Coral
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Kojis B. L. and N. J. Quinn (1981): Aspects of Sexual Reproduction and
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Kojis B.L. (1986b): Sexual reproduction in Acropora(Isopora) (Coelenter-
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Korringa P. (1947): Relations between the moon and periodicity in the
    breeding of marine animals. Ecol. Mongr. 17:345-381

Oliver J. K. (1992): Personal correspondence via computer mail.

Richmond R. H. and P. L. Jokiel (1984): Lunar Periodicity in Larva Re-
    lease in the Reef Coral Pocillopora damicornis at Enewetak and Ha-
    waii. Bull. Mar. Sci. 34(2):280-287

Richmond R. H. and C. L. Hunter (1990): Review - Reproduction and re-
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Sammarco P. W. (1982): Polyp Bail-Out: An Escape Response to Environment-
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 Glossary of Terms
allopatric - originating in or occupying different geographical areas.

asexual - designating or of reproduction without union of male and female
          germ cells: budding, fission are types of asexual reproduction.

broadcast - to cast or scatter eggs and sperm over an area for fertiliza-
             tion and distribution.

brooding - developing eggs within the body cavity or on external surface.

diel - see photoperiod.

embryogenic- the formation and development of the embryo.

fecundity - fertile, productive, prolific.

gametes - a reproductive cell that is haploid and can unite with another 
          gamete to form the cell that develops into a new organism.

gametogenic - process of consecutive cell divisions and differentiation
              by which mature eggs or sperm are developed.

gonads - an organ in animals that produces reproductive cells; esp., an 
         ovary or testis.

gonochoric - separate sexes, male reproductive organs in one individual and
            the female organs in another.

haploid - an organism or cell having only one complete set of chromo-
          somes ordinarily half the normal diploid number.

hermaphroditic - animal with sexual organs of both male (testes) and fe-
                 male (ovaries).

hermatypic - see hermaphroditic.

hydrodynamic - having to do with the motion and action of water and other
               liquids; dynamics of liquids.

morphological - form and structure, as of an organism, regarded as whole.

oocytes - an egg that has not yet undergone maturation.

oogenesis - the process by which the ovum is formed in preparation for
            its development.

photoperiod - the number of daylight hours best suited to the growth and
              maturation of an organism.

planulae - the ciliate, free-swimming larva of a coelenterate.

propagules - a structure that propagates an organism. 

sexual - designating or of reproduction by the union of male and female
         germ cells.

testes - male sex glands which secrete spermatozoa.

 Reef Breeding Conversion Equations
 Fahrenheit to Celsius
                               C = (5/9)*(F-32)
 Celsius to Fahrenheit  
                               F = (C*(9/5))+32
 Liters to US Gallons
                               G = L/3.8
 US Gallons to Liters
                               L = G*3.8
 PPM to ml/liter to mg/liter
                               mg/liter = ml/liter =~ PPM
 Liter to ml
                               1 ml = L/1000
 ml to microliter
                               1 microliter = 1000 ml

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