An old and massive colony of Pavona decussata is sexually active at high latitude (32°N) in Japan
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S. Keshavmurthy C. A. Chen Biodiversity Research Center
, Academia Sinica, Nangang, Taipei 115,
Taiwan
1
T. Mezaki (&) Biological Institute on Kuroshio
, Nishidomari, Otsuki-cho, Kochi,
Japan
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Although modular organisms like corals are often
portrayed as escaping senescence, which is natural in
other organisms, there are some evidences of
senescence in few coral species (Rinkevich and
Loya 1986; Irikawa et al. 2011, and references
cited therein). This raises a question whether old
coral colonies are sexually active and whether they
can reproduce successfully. We report here the
presence and spawning of a massive colony of
Pavona decussata (Fig. 1a), located within a
designated natural monument in Tatsukushi Marine
Park, Kochi Prefecture, Japan (132 52E; 32 46N),
where this species is quite common. In 1966, this
colony was measured to be 44.5 m long and 24.6 m
wide (Tokioka 1968). The present size of this colony
is 50.9 m long, 30.6 m wide, and 2.7 m in maximum
height, and it is believed to be 150 years-old.
We observed spawning by this old colony in 2011 and
2012, 6 days after the full moon during August. In 2011,
the colony started releasing eggs from 04:20 hours
(Fig. 1b). In 2012, most of the colony released eggs, but
a small part of it (1 3 m) started releasing sperm
15 min before releasing eggs (04:30 hours), which
might be a result of fusing genotypes. Spawning in the
colony continued for 30 min with the release of
positively buoyant sperm, and for 1.5 h with positively to
negatively buoyant eggs. Eggs and sperm were
successfully fertilized in the laboratory condition and
developed into larvae in 810 h. This massive colony of
P. decussata might be an important source of larvae in
and around Tatsukushi Marine Park.
Acknowledgments We thank our volunteer divers, Ms.
Mizuki Sano and Mr. Kazuya Hamaguchi from Tatsukushi
Fig. 1 a Wide-angle view of Pavona decussata colony in Tatsukushi Marine Park, Kochi, Japan. DKiuvrionsghioCeBnitoerlo,gaincadl MRes.seJaurnchkoFoFuunkdaadtai,one.xecutive head of
b Wide-angle and close-up (inset photo) view of the colony releasing eggs
(...truncated)