What influences predation by Coralliophila? Exploring the
relationships between corals, sym biotic zooxanthellae, and
corallivorous gastropods
Schmidt-Petersen Julia', O livier De C lerck1 and Rachel C ollin 2
1 W orking Group Phycology, Ghent University, Krijgslaan 281 S8, 9000 Gent, Belgium
E-mail: iulia.schm idtpetersen@ qm ail.com
2 Research Station Bocas del Toro, Sm ithsonian Tropical Research Institute, 9100 Panama C ity PI,
W ashington, D.C. 20521-9100, USA
Coral feeding gastropods can occur in high num bers and may have severe impacts on reefs, but
th e ir ecology is still poorly understood. This study explores which intraspecific variations o f corals
(such as depth, color m orph and associated zooxanthellae strain) influence predation by
corallivorous gastropods. Samples, field data and pictures o f corals and snails were taken in reefs
around Bocas del Toro, in the Caribbean region o f Panama. Zooxanthellae were identified by
Denaturing Gradient Gel Electrophoresis (DGGE), a fte r DNA was obtained from corals w ith a recently
developed m icro-invasive technique, using a syringe w ith a blunted needle, and was herein proven
to be applicable fo r a variety o f coral species. The study found th a t (1) corals o f the M onastraea
a n n u la ris com plex th a t incorporate w hite structures (‘w hite layer’) o f unknow n origin in th e ir tissue
are less often infested by C oralliop hila abbreviata. (2) When associated w ith one rare sym biont
strain o f clade B (8%), A cro po ra cervicornis bears higher densities o f C. caribaea than if associated
w ith the other, more com m on strain o f clade A (92%). General occupation rates o f A. cervicornis in
Bocas del Toro are low fo r C. a b b re via ta (4%) and high fo r C. caribaea (63%) com pared to other
locations in the Caribbean. (3) C. caribaea d iffers from its congener by not undergoing sex change,
a less destructive feeding strategy by prudent sessile feeding, which does not cause open lesions,
and seem ingly rem aining longer on the same coral polyp. T ogether w ith the known fact th a t it
tran sm its white-band-disease, the study suggests th a t high abundances o f C. a b b re via ta on
A. cervicornis are more alarm ing than o f C. caribaea, which should be addressed in fu rth e r studies.
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