11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
4-1
Coralline P/Ca: Evidence For A New Seawater PO4 Proxy
Michèle LAVIGNE* 1 , Robert M. SHERRELL 2 , M. Paul FIELD 1 , Eleni
ANAGNOSTOU 1 , Kim COBB 3 , Andréa G. GROTTOLI 4 , Braddock LINSLEY 5 , Gerard
M. WELLINGTON 6
1 Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ,
2 Institute of Marine and Coastal Sciences and Department of Earth and Planetary
Sciences, Rutgers University, New Brunswick, NJ, 3 School of Earth and Atmospheric
Sciences, Georgia Institute of Technology, Atlanta, GA, 4 School of Earth Sciences, The
Ohio State University, Columbus, OH, 5 Department of Earth and Atmospheric Sciences,
University at Albany, State University of New York, Albany, NY, 6 Biology and
Biochemistry, University of Houston, Houston, TX
A proxy for surface water nutrient concentrations, recorded in coral skeleton, would
provide novel records of sub-seasonal to centennial variations in nutrient dynamics and
primary production in the past. Records of tropical euphotic zone nutrient supply and
uptake could link decadal-centennial scale climate oscillations to low latitude carbon
fixation more directly than can be achieved using available paleo-SST/upwelling proxies
alone. A coral proxy for seawater phosphate would complement records from established
but quantitatively uncertain surface water upwelling proxies in coral such as Cd/Ca and
Ba/Ca. Using solution phase and laser ablation HR-ICP-MS methods, we have found that
average skeletal P/Ca in surface corals growing in regions with distinct nutrient regimes
(Gulf of Panamá (Pavona gigantea), Martinique (Montastrea faveolata), Pacific Line
Islands and Rarotonga (Porites lutea)) are positively correlated with mean local surface
phosphate concentrations. Further, a 4-year record along the growth axis of the Pavona
gigantea coral growing under seasonally varying nutrient levels in the upwelling regime
of the Gulf of Panamá shows repeated annual cycles of P/Ca (~75 -230 μmol/mol), with
maxima occurring during cool upwelling periods, following the ~3 fold seasonal
variations of surface water phosphate (LaVigne et al., in review). Based on rigorous
solution cleaning and soluble reactive phosphate analyses of drilled powders, we
hypothesize that the P/Ca signal measured by ICP-MS reflects a combination of inorganic
and organic intracrystalline phases, incorporated in proportion to ambient seawater
phosphate. We plan to further investigate the skeletal P incorporation mechanism and test
the validity of this new proxy in corals of different ages and nutrient environments.
Modern cores from the Pacific Line Islands (~160ºW, 2-4ºN) will be used to evaluate
coralline P/Ca (preliminary range ~30-60 μmol/mol) for reconstructing tropical Pacific
nutrient availability in relation to past ENSO-driven changes in equatorial upwelling.
4-2
U/ca As A Possible Proxy Of Carbonate System in Coral Reef
Alrum ARMID* 1 , Yuki TAKAESU 1 , Tanri FAHMIATI 1 , Hiroyuki FUJIMURA 1 ,
Tomihiko HIGUCHI 1 , Eiko TAIRA 2 , Tamotsu OOMORI 1
1 Department of Chemistry, University of the Ryukyus, Japan, Nishihara, Japan, 2 Aqua
Culture Okinawa, Japan, Nishihara, Japan
Increasing carbon dioxide in the atmosphere and absorption into the ocean will modify
the carbonate chemistry of the surface ocean. The atmospheric CO2 level has already
increased from the concentration of 280 ppm in the pre-industrial age to 380 ppm in
2007, and it is predicted to reach 560 ppm before the end of the 21 st century. Ocean
acidification influences calcium carbonate (CaCO3) equilibrium of the ocean due to the
decrease in carbonate (CO3 2- ) ion concentration. During calcification process of marine
carbonates (such as coral), some trace elements can be incorporated into carbonate
skeleton. Since the elevated atmospheric CO2 reduces the oceanic pH, and the alteration
of oceanic pH governs both the ocean carbonate chemistry and the speciation of
elements, the mechanism of trace elements incorporated into coral skeleton will be also
affected.
In seawater, UO2 2+ forms complex ions such as UO2CO3 0 , UO2(CO3)2 2- , and/or
UO2(CO3)3 4- . Uranium is thought to be incorporated into carbonate as uranyl (UO2 2+ ) ion.
However, the mechanism of their incorporation into coral skeleton based on the pH
changes is poorly understood. Therefore, study of such complex uranyl ions incorporated
into coral skeleton is significantly needed to establish basic concept of uranium uptake by
coral.
Incorporation of uranium into coral skeleton was investigated in the labotatory incubation
under the controlled pCO2 at 27°C. Distribution coefficient, λUO2, between coral
skeleton and seawater was measured, which varies from 2.6 to 0.6 with the change in
CO3 2- ion activity in seawater.
4-3
A Rayleigh-Based Approach To Coral Thermometry: Seeing Through The “Vital Effect”
Glenn GAETANI* 1 , Anne COHEN 1 , Zhengrong WANG 1,2
1 Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, 2 Yale
University, New Haven
Paleotemperature proxy records are typically derived from coral skeleton using empirical
relationships between elemental ratios and water temperature. While this approach has
produced significant advances in our understanding of Earth’s climate system, its accuracy is
limited by the impact of physiological processes (“vital effects”) on compositional variability
within the skeleton. Several recent studies have identified the importance of Rayleigh
fractionation in producing “vital effects” in coral skeleton, providing the basis for a new
approach to coral paleothermometry. In contrast with conventional paleothermometry, this
approach does not rely on calibrations involving living corals, and no prior knowledge of water
temperature is required. By combining analyses of multiple elemental ratios (Mg/Ca, Sr/Ca and
Ba/Ca) from a given coral skeleton with experimentally determined partition coefficients for
abiogenic aragonite, a mathematically overconstrained system of Rayleigh equations can be
constructed that describe element fractionations during coral biomineralization. While these
equations cannot be solved explicitly for temperature, global minimization techniques can be
used to derive ocean temperatures. The accuracy and precision of this approach was tested on
aragonite skeletons from two coral species grown in significantly different environments: (1)
Acropora sp., a symbiont-bearing tropical coral grown at 21 to 29°C by Reynaud et al. (2007,
Geochim Cosmochim Acta,71:354-362) and (2) Lophelia pertusa, an asymbiotic, cold-water
coral collected from a depth of 129 m on the Tisler Reef, NE Skagerrak, where water
temperature ranges from ~5 to ~9°C. Results from these corals show that our approach is yields
ocean temperatures that are both accurate and precise to within a few tenths of a degree, and
that it is applicable both across species and to corals growing in vastly different environments.
4-4
Identification And Calibration Of Proxies For Thermal And Disease Stress From Lipid
Biomarkers
Jessie KNEELAND* 1 , Konrad HUGHEN 1 , James CERVINO 2,3 , Erich BARTELS 4
1 Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole,
MA, 2 Pace University, New York, NY, 3 Marine Chemistry and Geochemistry, Woods Hole
Oceanographic Institution, Woods Hole, 4 Mote Marine Laboratory, Summerland Key, FL
New lipid biomarkers indicative of thermal and disease stress on corals are important for
assessing coral health, and lipids also have the potential for preservation in coral aragonite. To
identify such stress biomarkers, we cultured Symbiodinium zooxanthellae clade subtypes A, B,
C1 and D1 at one-degree temperature increments (24-32 degrees C), with and without
introduction of Vibrio pathogens, for 1 to 5 weeks. We also performed analagous incubations of
whole coral samples of Montastraea faveolata from Summerland Key, Florida. Lipids were
extracted from the cells using a Bligh and Dyer protocol, and were analyzed by gas
chromatography and mass spectrometry. Triplicate cultures under each set of conditions were
analyzed up to three times each to ensure a reproducible signal. Resulting indices are calculated
as ratios of lipids, providing a robust measure that is not sensitive to total lipid abundance and
non-constant sample size. The ratios of fatty acid to sterols, and unsaturation ratios in the fatty
acids respond strongly to both increasing temperatures and length of exposure. Comparisons
between cultured Symbiodinium lipids and coral tissue, and comparisons between diseased and
non-diseased samples, demonstrate the potential for biomarkers as thermal and disease stress
proxies.
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