11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 11: From Molecules to Moonbeams: How is Reproductive Timing Regulated in Coral Reef Organisms?
11-9
Reproductive Pattern Of The Polychaete Sabellastarte Spectabilis in Hawaii.
David R. BYBEE* 1 , Julie H. BAILEY-BROCK 2 , Clyde S. TAMARU 3
1 Department of Biology, Brigham Young University-Hawaii, Laie, HI, 2 Department of
Zoology, University of Hawaii, Honolulu, HI, 3 Sea Grant College Program, University of
Hawaii, Honolulu, HI
The objective of this study was to determine the timing of reproduction in the Sabellid
polychaete Sabellastarte spectabilis (Grube 1878) and to correlate reproductive activity
with water temperature and day length. Worms were collected at approximately monthly
intervals from Jan. 2002 to Dec. 2003 from intertidal and subtidal reefs in Kaneohe Bay,
Hawaii, USA (21° N, 157 ° W). Reproductive activity was investigated qualitatively
using histological techniques and quantitatively with induction of spawning trials.
Worms were characterized into four discrete reproductive stages based on histological
evidence: 1) No evidence of reproductive activity in the coelom 2) Only coelomocytes
present in the coelom 3) Some gametes present in the coelom and 4) Coelom densely
packed with gametes. Stage 4 worms were present over an extended period of time
(females, March-December and males, March-November) indicating a potentially broad
reproductive season. No correlation between day length and maturation stages in S.
spectabilis was detected. However, there was a correlation between water temperature
and % frequency of Stage 4 worms. Maturation appeared to coincide with water
temperatures of 24 to 25 ºC (March – September) after which there was a reduction in the
% frequency of stage 4 individuals. Induction of spawning trials conducted between May
– January showed the month of October with a significantly higher percent success than
any other month investigated. According to all available information (e. g., natural
spawning in water tables, histological data, induction of spawning trials, correlation of
maturation stages with observed changes in average monthly water temperature.), there is
an apparent peak in reproductive activity (spawning) within a broad maturational season,
which may be influenced by water temperature.
11-10
The Effects Of Temperature And Light On The Gametogenesis And Spawning Of
Four Sea Urchin And Five Sea Cucumber Species On Coral Reefs in Kenya And La
Reunion
Nyawira MUTHIGA* 1 , Chantal CONAND 2 , Joan KAWAKA 3 , Sophie KOHLER 4
1 Marine Program, Wildlife Conservation Society, Bronx, NY, 2 Laboratoire de biologie
marine, Université de La Réunion, Saint Denis, France, 3 Wildlife Conservation Society,
Mombasa, Kenya, 4 University de La Reunion, Saint Denis, France
This paper reviews studies of the reproductive cycles of 4 species of sea urchins
(Echinometra mathaei, Diadema savignyi, D. setosum, Tripneustes gratilla) and 5 species
of sea cucumbers (Actinopyga echinites, Holothuria atra, H. leucospilota, H. scabra and
Stichopus chloronatus). Measurements of gonad index and macro and microscopic
observations of gonads were used to evaluate changes during gametogenesis in
individuals collected on Kenyan and Reunion reefs. The effects of temperature, light and
lunar period were also assessed. Echinometra mathaei, H. arenacava, H. leucospilota in
Kenya and H. atra in Reunion showed an annual pattern while A. echinites, H.
leucospilota and S. chloronatus in Reunion and H. scabra in Kenya showed a biannual
pattern of reproduction. A particularly pronounced seasonal pattern occurred in E.
mathaei, H. arenacava and H. leucospilota on Kenyan reefs where gametogenesis started
in July when temperatures and light were at their lowest and spawning peaked between
March-April just after peak levels of temperature and light. These species showed higher
correlations between light and gonad index than between temperature and gonad index
indicating that light had a stronger influence than temperature on the onset of
gametogenesis on these species on the Kenyan coast. In the species without pronounced
annual reproductive patterns, gonad indices were high during one (D. setosum, D.
savignyi, T. gratilla in Kenya) or two (A. echinites, H. leucospilota and S. chloronatus in
Reunion and H. scabra in Kenya) periods of 1 - 2 and up to 6 months but the
reproductive season often coincided with periods of high temperature and light. Only
three of the sea urchin species (D. savignyi, D. setosum and T. gratilla) showed lunar
periodicity.
11-11
Gametogenic and reproductive cycles of a sea anemone that provides essential habitat for
anemonefish
Anna SCOTT* 1,2 , Peter HARRISON 3
1 Coral Reef Research Centre, Southern Cross University, Lismore, Australia, Coffs Harbour,
Australia, 2 National Marine Science Centre, Coffs Harbour, Australia, Coffs Harbour, Australia,
3 Coral Reef Research Centre, Southern Cross University, Lismore, Australia, Lismore,
Australia
Sea anemones that host obligate symbiotic anemonefish are ecologically important throughout
many reefs of the Indo-Pacific. Despite their importance there is very little information
available on their sexual reproductive biology. This study aimed to address this lack of
knowledge by determining the gametogenic cycles of the sea anemone, Entacmaea quadricolor.
Gonad samples were taken in the field using a specially developed biopsy sampling technique
from January 2003 to February 2005 at North Solitary Island, Solitary Islands Marine Park,
Australia. On each sampling occasion, 15 to 20 individuals were sampled, with the depth,
colour and pedal disc diameter of each anemone being recorded. Samples were fixed and
histological sections were prepared to determine the state of reproductive activity for each
individual. All oocytes sectioned through the nucleus were measured and assigned to size
classes of 150 μm. Males were classified into one of five stages based on assessment of
spermary maturity. Spawning was inferred by the disappearance of the largest size class of
oocytes in the females, and the disappearance of mature spermaries and the appearance of the
ruptured or spawned mesenteries in the males. E. quadricolor had separate sexes at the study
location, with female anemones being significantly more abundant than male anemones. Female
anemones displayed asynchronous oocyte development, both within and among individuals,
whereas male anemones showed a single cycle of spermary growth, development and spawning.
Six spawnings, which occurred between January and April, were inferred over the study period.
On all but one occasion both female and male anemones were inferred to have spawned during
the same period. Due to ease of interpretation, the developmental pattern of the spermaries may
therefore provide a better indicator of spawning times in this species.
11-12
Mass Coral Spawning Events At Reunion Island (21°s) From 1991 To 2007
Mireille M.M. GUILLAUME* 1,2 , Maurice PARMANTIER 2 , J. Henrich BRUGGEMANN 2
1 Milieux et Peuplements Aquatiques, UMR 5178 CNRS-UPMC-MNHN, Muséum National
d'Histoire Naturelle, Paris, France, 2 ECOMAR, Université de la Réunion, Saint-Denis, Reunion
The occurrence of mass coral spawning has been checked intermittently at Reunion Island since
1985. In 1991, M. Parmantier discovered the timing of mass spawning in A. muricata and
surveyed one coral patch annually until 2003. While correlation to full moon was confirmed,
the month and exact timing varied between years.
The objectives of the present study are to inventory the species involved and analyze the timing
of mass spawning in relation to environmental parameters susceptible to trigger these events.
Mass spawning events were surveyed from 2004 to 2007 on three coral reefs (Saint-Gilles, la
Saline and Saint-Leu) during the four nights following full moon in August to December,
involving each night ~20 observers from the University of Reunion. Temperature was recorded
in situ at each reef, while solar insolation is available by Météo France. Few species contributed
to mass spawning on the shallow reef flats, the dominant species Acropora muricata, both
ecomorphs of A. digitifera, A. vaughani and sometimes A. gemmifera. The long-term spawning
record (1991-2007) of A. muricata is analyzed with environmental data. Mass spawning
occurred when SST was the lowest, in October or November, once in September. Coral
spawning was clearly related to the lunar cycle, occurring from the 1st to the 4th day after full
moon, 1 to 2.5 hours after the night-time low tide, but not later than midnight. Gamete release
coincides with the incoming flow by night, following the tidal wave that sweeps the West coast
of Reunion Island from South to North. Synchrony is high between reef flats, but A. muricata at
one site at la Saline, may be one month in advance. Corals on outer reef slopes spawn together
with those on reef flats, but not yearly.
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