11th ICRS Abstract book - Nova Southeastern University

Poster Mini-Symposium 19: Biogeochemical Cycles in Coral Reef Environments
19.774
Spatial Differences Of The Linear Extension Of Pocillopora Damicornis In Polhena
Reef Of Southern Sri Lanka
Wickrama Arachchige UPASANTA KUMARA 1 , Wickrama Arachchige UPASANTA
KUMARA* 1
1 Oceanography and Marine Geology, University of Ruhuna, Matara, Sri Lanka
A total of 65 approximately same sized colonies of P. damicornis situated in inshore
patchy reefs located at the leeward side of the fringing reef in Polhena in Southern coastal
belt of Sri Lanka were surveyed. All the measurements were taken every fortnight.
This study took place on three slopes of the reef front, side and back and identified as
sites. Three locations were selected in each site as surface, bottom and middle
considering the depth.
Mean, standard deviation and one–way ANOVA was used during the statistical analysis.
Multiple comparisons were done using least significant different (LSD) for light intensity
and sediment volume. The water parameters observed were 28.06±1.14 0 C, 8.78
±0.40mgL -1 , 1.40±0.32 mgL -1 , 31.91±3.49 ppt, 8.12±0.04*10 3 , 1.01±0.61 mgL -1 ,
5.78±2.37NTU, 49.17±1.89Lux and 90.08±39.65mL respectively. It was observed that
the mean difference of light intensity and sediment volume between each location was
significantly different. Higher sediment volume and lowest diameter extension were
observed at back bottom (0.055±0.01mm day -1 ). The highest value was observed at front
surface (0.22±0.01mm day -1 ). ANOVA showed a significant difference of the diameter
extension of P. damicornis between locations and sites. Diameter extension was
significantly low at back showing a significant negative correlation with increased
sedimentation rate (7897.26gm -2 day -1 ).
19.775
The Role Of Oceanographic Processes in The Trophic Ecology Of Coral Reefs:
Linking Reef Biodiversity And Biogeochemistry
Alex WYATT* 1 , Stuart HUMPHRIES 2 , Anya WAITE 1 , Ryan LOWE 1 , Russ
BABCOCK 3
1 School of Environmental Systems Engineering, The University of Western Australia,
Crawley, Australia, 2 Department of Animal & Plant Sciences, University of Sheffield,
Sheffield, United Kingdom, 3 Marine and Atmospheric Research, CSIRO, Wembley,
Australia
Rapid recycling of sparse nutrients as a means of sustaining productivity is a paradigm
that suggests that reefs are largely independent of the surrounding ocean, being neither a
net source nor sink of nutrients. Recently studies have begun to suggest that reefs may be
closely linked to the ocean, and perhaps more dependent on its variability, than
previously considered. Our recent work at Ningaloo Reef, Western Australia
demonstrates considerable depletion of phytoplankton (measured via chlorophyll a) in
oceanic water pumped over the reef by wave action. Based on this depletion, we
postulate the idea of an oceanic reef “catchment”: the area of ocean which sustains reef
productivity. By linking depletion rates across the reef to local and regional
oceanography, we estimate the size of this catchment to be on the order of 10,000 km2
for the 290 km stretch of Ningaloo. Uptake of phytoplankton alone represents a nitrogen
flux to the reef that may be up to an order of magnitude higher than typically reported for
dissolved nitrogen, confirming that particulate feeding may be a missing link in reef
nitrogen budgets. We used stable isotope biomarkers to determine which components of
the reef biotope regularly utilise ocean-derived particles and are therefore closely coupled
to offshore oceanographic processes. Our work consequently has significant implications
for the impact that human- and climatically-induced changes in the surrounding ocean
may have on coral reefs, particularly for those organisms most dependent on oceanic
supply.
19.776
Metabolic Responses And Defense Mechanism By Coral galaxea Fascicularis Against
Increased Hydrogen Peroxide in Seawater
Tomihiko HIGUCHI* 1 , Hiroyuki FUJIMURA 1 , Takemitsu ARAKAKI 1 , Tamotsu OOMORI 1
1 University of the Ryukyus, Nishihara, Japan
Coral reef decline has recently been observed around the world, caused by changes in the
environment following natural and anthropogenic activities. Hydrogen peroxide (H2O2), a
strong active oxygen species, is one of the photochemically formed chemicals in both seawater
and atmosphere. Because of its strong oxidizing power, H2O2 affects plants and marine
organisms. Increases in seawater temperature, irradiance, UV radiation can result in the
formation of harmful, reactive oxygen species within zooxanthellae and coral hosts. The
cellular response to the formation of oxygen radicals has many defense mechanisms that include
the increased activity of free radical scavenger enzymes such as superoxide dismutase (SOD)
and catalase (CAT). SOD catalyzes the dismutation of superoxide into oxygen and H2O2, and
CAT is responsible for degrading H2O2 into water and oxygen. Our study tried 1) to obtain
quantitative information on coral’s metabolic changes with increased H2O2 and 2) to
investigate defense mechanisms by zooxanthellae and host corals against increased H2O2 in
seawater. The corals, Galaxea fascicularis, were exposed to various concentrations of H2O2 (0,
0.3, 3 µM). When H2O2 was added to the seawater, we observed clear changes in the coral
metabolisms. Higher concentrations posed more stress to the coral colonies. Within 3 days,
photosynthesis and calcification were decreased by the increased H2O2, but respiration was not
affected. In the exposure experiments, CAT activities of both zooxanthellae and host corals
were increased, but SOD activities were un-changed. It was suggested that coral have a defense
mechanism against increased H2O2 in seawater. However, coral photosynthesis and calcification
system received damages by the increased H2O2. Thus, though CAT activities were increased,
they were not sufficient to scavenge all of the H2O2. The hydroxyl radical generated by the
remaining H2O2 could have caused damages to the coral metabolic systems.
19.777
Pumping Of Pore Water Nutrients By The Upside-Down-Jellyfish Cassiopeia Sp. in Coral
Reefs
Carin JANTZEN* 1 , Christian WILD 2 , Mohammed RASHEED 3 , Claudio RICHTER 1
1 Center for Tropical Marine Ecology (ZMT), Bremen, Germany, 2 Coral Reef Ecology Work
Group (CORE), Center of Geobiology and Biodiversity Research, München, Germany,
3 Marine Science Station Aqaba, Aqaba, Jordan
The jelly fish Cassiopeia sp. is common in coral reefs, seagrass beds and mangrove ecosystems.
As opposed to the fully pelagic other members of the Rhizostomidae, this unusual medusa leads
a quasi benthic phototrophic life, where its peculiar swimming orientation, upside-down against
the substrate, is believed to be associated with exposing its zooxanthellae-laden mouth arms to
suitable levels of light. Here we show that the concave bell of Cassiopeia sp. also acts as a
suction pump, effectively drawing nutrient-rich pore waters from permeable coral reef
sediments, thereby enhancing photosynthesis of the zooxanthellae. Chamber incubations with
fluorescein-labelled pore water revealed two orders of magnitude increased pore water fluxes
across the sediment-water interface in the presence of Cassiopeia sp., with an exchange of at
least 1 cm deep pore water within one hour. Accompanying nutrient uptake experiments
revealed effective assimilation of ammonia and phosphate by the jellyfish. As natural
abundances of Cassiopeia sp. in coral reefs may exceed 10 individuals m -2 , this previously
overlooked ecosystem engineer may harness a significant fraction of sediment-locked
regenerated nutrients, thereby facilitating pelagic-benthic coupling and primary production in
coral reefs.
457