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Vol. 52, 2013
Effects of grazing by herbivorous gastropod (Trochus niloticus) on the survivorship of
cultured coral spat
Ronald
D Villanueva1*, Maria Vanessa B Baria1,2 and
Dexter W dela Cruz1,3
1The
Marine Science Institute, College of Science, University of the
Philippines Diliman, Quezon City 1101, Philippines
2Present address: Sesoko Station, Tropical Biosphere
Research Center, University of the Ryukyus, Motobu, Okinawa 3422, Japan
3Present address: Marine Ecology Research Centre,
School of Environment, Science and Engineering, Southern Cross
University, Lismore, New South Wales 2480, Australia
Abstract
Background: The technology in the
production of sexual coral propagules for coral reef restoration is
being actively developed recently to address concerns on the low
genetic diversity in coral populations restored through transplantation
of coral materials derived from fragmentation.
Results: In this study, we produced coral spat
attached to rubble and determined the effect of the addition of
hatchery-reared trochus, a herbivorous gastropod, at two densities (one
and two trochus per cage, equivalent to four and eight trochus per
square meter, respectively) on the survivorship of the spat cultured in
cages at the hatchery and in situ
nursery. After 5 weeks of culture in the hatchery, spat survivorship
was significantly higher in the two per cage trochus treatment (18.3% ±
6.7%, mean ± sd) than in the control (5.5% ± 1.7%), with the one per
cage trochus treatment having intermediate spat survival (12.6% ±
7.9%). The enhanced spat survivorship, though not apparent in the in situ nursery culture, is
attributed to the grazing effect of trochus as significantly lower turf
algal cover was observed in rubble placed in two per cage trochus
treatment (44.8% ± 3.2%) than in the one per cage trochus treatment and
control (80.2% ± 6.5% and 76.3% ± 5.0%, respectively).
Conclusions: This study
demonstrates that trochus can be used to control algal cover and
enhance survivorship of coral spat in caged culture, at least in the
hatchery, for the production of sexually derived transplant materials
for coral reef restoration.
Key words: Coral; Restoration; Trochus
niloticus; Acropora valida.
*Correspondence: E-mail: villanuevr@yahoo.com
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