11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 5: Functional Biology of Corals and Coral Symbiosis: Molecular Biology, Cell Biology and Physiology
5.104
Capacity For Plastic Growth Response Of porites Lobata in Fluctuating
Temperature Regimes Varies Between Colonies
Tyler WATERSON* 1 , Daniel BARSHIS 2 , Jonathon STILLMAN 3
1 Marine Biology, Romberg Tiburon Center, San Francisco State University, Tiburon,
CA, 2 Zoology, Hawai'i Institute of Marine Biology, Kaneohe, HI, 3 Biology, Romberg
Tiburon Center, San Francisco State University, Tiburon, CA
In the back reef lagoons of Ofu, American Samoa, corals thrive in temperatures (up to
360C) higher than most corals can tolerate, and daily temperature fluctuates 2-40C
depending on the size and flow of the pool. A reciprocal transplant study of two massive
Porites species showed that corals from both forereef (constant temperature) and back
reef environments grow more quickly in the back reef lagoon, although native back reef
corals grow more quickly in all environments relative to conspecifics from the forereef.
Here we examined whether these growth differences were due to temperature or other
environmental factors, and whether growth responses were correlated with genotype. We
collected samples of Porites lobata from forereef and back reef sites, with n=5 colonies
per site and 25-30 replicates per colony. We transported the corals to our laboratory and
split them between two tanks imitating either the forereef (290C) or back reef (fluctuating
27-320C). After one month, new vertical tissue extension was measured. Both back reef
and forereef corals had significantly higher tissue extension rates in the fluctuating tank
than the constant-temperature tank, indicating phenotypic plasticity in growth in response
to temperature. As in the field, back reef corals had significantly higher vertical tissue
extension rates than forereef corals. However, colony-specific responses varied within
each source environment. We hypothesize that this is an effect of host genetic
polymorphism since no variation has been detected in the genotype of symbiodinium
associated with P. lobata at this site (all colonies examined thus far host a similar strain
of clade C). High genetic diversity has been seen in Porites species on this reef and we
are currently examining the host genotype of the colonies studied using sequence
homology of the internal transcribed spacer (ITS) region of nuclear ribosomal dna to
compare growth responses with genotype.
5.105
Feeding Corals in Captivity: The Role Of Prey Type And Prey Concentration
Ronald OSINGA* 1 , Tim WIJGERDE 1 , Fam CHARKO 1 , Johan VERRETH 1 , Dirk
GRYMONPRE 2 , Silvia LAVORANO 3
1 Wageningen University, Wageningen, Netherlands, 2 INVE BV, Dendermonde, Belgium,
3 Acquario di Genova, Genova, Italy
Corals feed heterotrophically to complement the nutrition they obtain through
photosynthesis by zooxanthellae. Within the project CORALZOO (a collaboration
between zoo’s and scientists), feeding efficiencies and growth rates of five species of
corals are studied using different food types and concentrations. A protocol-template for
feeding of corals in captivity will be deduced from the results.
Colonies of the branching species S. caliendrum were used to study the uptake of live
nauplii at different starting concentrations (1,000 – 20,0000 nauplii / l). Colonies of this
species were incubated with nauplii in a mildly stirred, 1,5 l Perspex chamber. Uptake
rates were remarkably high: a 14 ml coral colony could capture up to 10,000 nauplii
within 15 minutes. At high starting concentrations, saturation occurred after 10 to 45
minutes, while at lower starting concentrations, the incubation chamber was in most cases
almost cleared of nauplii after 30 minutes.
Long-term growth experiments with the branching coral Pocillopora damicornis showed
that Artemia nauplii were a better food source than microalgae (Nannochloropsis sp.) and
rotifers (Brachionis sp.). Most optimal was a (daily) start concentration of 2,000 nauplii
per l.
The boulder-shaped Galaxea fascicularis was used to test the ability of corals to capture
four different Artemia-based feeds: live nauplii, dead (pasteurized) nauplii, Selcoenriched
Instar II nauplii and Selco-enriched Instar II nauplii supplemented with a test
compound. The corals preferred live over dead nauplii. Capture efficiency of Instar II
nauplii was lower than for freshly hatched nauplii, but not significant when normalized to
carbon content. Supplemented Instar II was captured with the same efficiency as nonsupplemented
Instar II, which may enable development of tailor-made Artemia-based
coral feeds in the near future.
5.106
Preliminary Results: Reproduction And Zooxanthellae Of millepora Platyphylla
Alan DAVIS* 1
1Kagman High School, Saipan, Northern Mariana Islands
Millepora spp. hydrocorals initiate reproduction by liberating medusae that develop
encapsulated in ampullae within the corallum; medusae spawn and die within hours.
Zooxanthellae are acquired by eggs before medusae leave the colony. Reproductive state of
Millepora platyphylla was studied sporadically from 1984 through 1986 on Guam, by
monitoring presence of ampullae in collected hard parts. Tissue specimens were collected for
light microscopical study, and embedded in paraffin.
Medusae were released three or four days after Full Moon beginning in April in both 1985 and
1986, followed by monthly liberation for some months. M. dichotoma began showed a similar
pattern, albeit later in the summer, as M. platyphylla apparently wound down its season.
Some days prior to liberation of medusae, reproducing colonies change to a marked darker
brown color, and colonies’ surfaces are peppered with numerous minute white rings, evidence
of decalicification of overburden of ampullae.
Ordinary coccoid zooxanthellae stay near the tissue surface. Prior to liberation of medusae,
certain structures appear to move through the coenosarc canals. It is proposed that these are
zooxanthella swarmers, and suggested that as they move through basement layers they are able
to enter the medusae and infect the egg: apparently the putative swarmers convert into coccoid
zooxanthellae immediately, when they enter the medusae.
These preliminary results suggest that linked sexual reproductive cycles are crucial to the
vertical transmission of zooxanthellae in Millepora spp. Further research is demanded, to
elucidate the details of these events. Individual cycles of both animal and plant demand to be
carefully studied, and the nature of these complex interactions and such signals as enable the
coordination of their life cycles. Subsidiary observations of Millepora platyphylla likewise
highlight the importance of research on these key species.
5.107
Mechanisms Of Microhabitat Segregation Among Corallimorpharians: Evidence From
Physiological Parameters Related To Photosynthesis And Host Cellular Response To
Irradiance.
Baraka KUGURU* 1 , Nanette E. Chadwick CHADWICK 2 , Yair ACHITUV 3 , Sophie DOVE 4 ,
Ove HOEGH-GULDBERG 5 , Dan TCHERNOV 6
1 Life Science, Interuniversity Institute for Marine Science, Eilat, Israel, 2 Biological Sciences,
Auburn University, Auburn, AL, 3 The Mina and Everard Goodman Faculty of Life Sciences,
Bar Ilan University, Tel aviv, Israel, 4 Centre for Marine Studies, University of Queensland,
Australia, Australia, 5 Centre for Marine Studies, University of Queensland, Queensland,
Australia, 6 Life science, Interuniversity Institute for Marine Science, Eilat, Israel
Corallimorpharians are evolutionarily important relatives to stony corals, yet little is known
about their ecophysiology. We show here that variation in the photoacclimation responses of
some corallimorpharians explains in part their distribution and abundance on shallow reef flats.
Our experimental exposure of corallimorpharians to the synergistic effects of UVR and PAR
caused reduction of zooxanthella abundance, FV/Fm, and sigma values, while it caused an
increase in QM, host cellular enzymatic activity (SOD), cellular degradation (LPO), MAAs, and
GFPs. The corallimorpharian Rhodactis rhodostoma was physiologically less sensitive than
Discosoma unguja when exposed to the synergistic effect of PAR and UVR. While our
previous study showed that zooxanthellae in both host species photoprotected the host tissues
from high light pressure by quenching the excitation energies through NPQ, the present study in
addition, found that the host cells synthesized UVR absorbing compounds such as MAAs and
GFPs, which functionally sun-protected the zooxanthellae. The R. rhodostoma host synthesized
MAAs which absorb in the UVB range (300nm - 320nm), while D. unguja synthesized MAAs
which absorb in the UVA range (320nm - 340nm), explaining in part why R. rhodostoma is able
to acclimate better than D. unguja in shallow areas which are characterized by high UVB.
Because some species are more affected than others by increased levels of ambient UVB
radiation, significant changes in community structure are likely to occur in the near future on
coral reefs.
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