11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
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The P/ca, Ba/ca, And B/ca Proxies in The Solitary Deep Sea Coral d.dianthus:
Mapping And Sources Of Contamination
Eleni ANAGNOSTOU* 1 , Robert SHERRELL 2 , Michele LAVIGNE 1 , Jess ADKINS 3 ,
Alex GAGNON 4
1 Institute of Marine and Coastal Sciences, Rutgers University, New Brunswick, NJ,
2 Institute of Marine and Coastal Sciences/ Department of Earth and Planetary Sciences,
Rutgers University, New Brunswick, NJ, 3 Division of Geological and Planetary Sciences,
California Institute of Technology, Pasadena, CA, 4 Division of Chemistry, California
Institute of Technology, Pasadena, CA
We present skeletal proxies for nutrient and carbonate system seawater properties by
measuring elemental ratios in globally distributed modern samples of D. Dianthus. Mean
P/Ca, Ba/Ca, and B/Ca ratios for each coral, integrating multiple years of growth, are
obtained for lines along the exterior surfaces of septa using 193nm laser ablation HR-
ICP-MS, and are regressed against hydrographic data from nearby stations. P/Ca is
strongly correlated with seawater phosphate (DPO4~0.7, where D=element/Ca in coral
divided by element/Ca in seawater; R 2 ~0.85), and Ba/Ca with seawater dissolved barium
(DBa~1.8, R 2 ~0.96), while B/Ca is positively correlated with seawater pH. Additionally,
we present 2-D maps of P/Ca, Ba/Ca, and B/Ca across different skeletal features
including centers of calcification and surrounding aragonite, to identify possible nonenvironmental
factors influencing skeletal elemental ratios. We also examine patterns of
appearance of contaminant iron/manganese phases enriched in phosphorus that are
incorporated into the skeletal structure. Finally, we summarize the above results to
present possible mechanisms of incorporation of phosphorus, barium, and into the coral
aragonite to explore the potential and feasibility of applying these deep sea coral proxies
for reconstruction of past nutrient and carbonate system distributions.
4-22
Stable Isotopes And Sr/ca Ratios Indicate Records Of Groundwater Influence On
Florida Reefs
Peter SWART* 1 , Sarah BELLMUND 2 , Richard DODGE 3 , Kevin HELMLE 4 , Rene
PRICE 5 , Jeremy STALKER 5
1 MGG, University of Miami, Miami, FL, 2 NPS, Miami, FL, 3 Oceanographic Center,
Nova Southeastern University, Dania, FL, 4 Oceanographic Center, Nova Southeatern
University, Dania, FL, 5 Geology, Florida International University, Miami, FL
The waters off Elliot Key, within Biscayne National Park (BNP) in the United States,
contain some of the longest lived specimens of Montastraea faveolata in the Caribbean.
Previously we have noticed an inconsistency between measured water temperatures and
temperatures estimated using the Sr/Ca and the 18O of the coral skeletons. This
inconsistency is a result of the fact that the reefs are influenced by evaporated water
emanating from Biscayne Bay as well as groundwater from the adjacent mainland. The
water from Biscayne Bay is elevated in 18O, which influences the reefs to a greater
extent during the summer thereby depressing the 18O amplitude of the skeleton. At the
same time the ground and surface waters are highly elevated in calcium, resulting in
lower than expected Sr/Ca ratios. This enhances the range of Sr/Ca in the corals. By
combining these two proxies with measured SST data, it is possible to use the corals as
proxies of the amount of freshwater discharge from the adjacent mainland. It is possible
to distinguish surface water from ground water using the Ba/Ca ratio. Surface waters
have elevated Ba/Ca ratios compared to ground water, and therefore distinctions between
surface discharge and groundwater discharge can be assessed using this ratio in the coral
skeletons. In this presentation we present (i) high resolution reconstructions (>40
samples per year) over the past 50 years from three sites in Biscayne National Park, and
(ii) a lower resolution record extending back to ~1750.
4-23
Historical Land Use Patterns Recorded By Coral Chemistry From Moloka‘i, Hawaii
Nancy GRUMET PROUTY* 1 , Michael FIELD 1
1 Coastal and Marine Geology, U.S.G.S., Santa Cruz, CA
Land-use practices, such as clearing and agriculture, can degrade river catchments and increase
the amount of sediment flowing in rivers to the coastal ocean. An increase in erosion on the
island of Moloka‘i, Hawaii has been linked to intensification of farming, clearing of native
vegetation, and introduction of both feral and domesticated grazing animals. The fringing reef
of Moloka‘i’s southern coast has been the focus of several studies to understand the dynamics
of sediment transport and its impact on coral reef health. These results have documented
chronic turbidity in coastal waters that results from both flood discharge following heavy rains
from a Kona storm and daily suspension of terrigenous sediment by trade-wind waves. The belt
of suspended sediment extends across the reef flat and beyond.
It is difficult, however, to decisively demonstrate a clear link between land use patterns and
changes in coral condition based on surveys alone. Geochemical proxy records from corals
offer a technique for recording environmental changes. Because suspended sediment in river
water contains minor levels of barium, as the river water enters the ocean, barium is carried to
the ocean where corals incorporate it into their skeletons. Thus, coral Ba/Ca records provide insitu
baselines of past seawater quality. We collected a suite of coral cores from P. lobata heads
from the fringing reef off south Moloka‘i to investigate the link between sedimentation and
coral reef ecosystem health due to chronic exposure to sedimentation; we also investigated the
effects of infrequent, large scale events and perturbations due to modification of the coastline.
Our results were compared to historical information from adjacent watersheds to compare
present day conditions with those of the past several decades.
4-24
Geochemical Analyses From Florida’s ‘Monster Coral’: Reconstructing Environmental
Changes From The Port Everglades Area Over The Last 100 Years
Amanda WAITE* 1 , Kevin HELMLE 2 , Richard DODGE 2 , Peter SWART 1 , J. Harold
HUDSON 3
1 Marine Geology and Geophysics, Rosenstiel School of Marine and Atmospheric Science,
University of Miami, Miami, FL, 2 National Coral Reef Institute, Nova Southeastern University
Oceanographic Center, Dania, FL, 3 FKNMS (retired), NOAA, Miami, FL
In 2005, a 300+ year old colony of the star coral, Montastraea faveolata, was cored in 20 feet of
water approximately 2 miles south of Port Everglades, Florida USA. Given the coral’s latitude
and proximity to the activity and impact of a large urban population and a large shipping and
cruise port, it is considered exceptional for both its age and size. The specimen therefore may
provide insight into the effects of South Florida’s development on corals over time. Stable
isotopic analysis of this coral’s skeleton reveals δ18O values between -4.1 and -2.6‰, and
δ13C values between -3.5 and +0.4‰. Both the oxygen and carbon isotopes demonstrate
regular seasonal cyclicity. Minor element concentrations were also measured. Ratios of Sr/Ca,
Mg/Ca, and Ba/Ca vary between ~9.1 and 9.6 mM/M, 5 and 13 mM/M, and 4.5 to 6.5 mM/M
respectively, and depict annual fluctuations in concentration. X-radiography of slabs from this
coral’s skeleton reveals a 300 year chronology of seasonal density banding along with a period
of anomalously high density from 1940 to 1970 which suggests that some sort of stress was
acting on the coral. Re-evaluating the geochemical data in light of this density anomaly reveals,
with few exceptions, little difference between the typical modern growth and the relatively high
density period between 1940 and 1970. The exception to this is in the amplitude of stable
isotopic variation, which does appear to be slightly suppressed where density was anomalously
high in the coral with δ18O from -3.8 and -2.6 ‰ and δ13C between -2.5 and +0.4‰.
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