11th ICRS Abstract book - Nova Southeastern University

Oral Mini-Symposium 4: Coral Reef Organisms as Recorders of Local and Global Environmental Change
4-17
Water Quality in Nearshore Areas Of The Great Barrier Reef: A Large Scale
Monitoring Program And An Assessment Of The Use Of Benthic Foarminifera As
Water Quality Indicators
Sven UTHICKE* 1 , Schaffelke BRITTA 1 , Angus THOMPSON 1 , Damian THOMSON 1
1 Water Quality, Australian Institute of Marine Science, Townsville MC, Australia
As for most Coral Reefs, a potential decline in water quality (WQ) is a concern for reef
health of Great Barrier Reef (GBR) inshore reefs. A large scale (32 reefs, 4 regions) GBR
inshore monitoring program was initiated in 2005, encompassing annual coral
community analysis, and half-yearly WQ measurements. We additionally investigated the
benthic foraminifera at these monitoring sites to evaluate their utility as WQ indicators in
the GBR. WQ measurements confirmed that most parameters (e.g. chlorophyll a,
suspended solids) are higher in inshore areas of the GBR when compared to offshore
reefs. Higher concentrations of most parameters were measured during the wet season,
but regional differences in WQ were more distinct in the dry season.
Regional differences in coral cover and community composition are pronounced. A
substantial proportion of the variation in coral community composition is explained by
differences in the hydrodynamic conditions, with several genera resilient to
sedimentation attaining consistently higher relative abundance in areas where fine
sediments predominate. Coral cover estimates mostly reflect recent disturbance history
rather than WQ conditions. Along a distinct WQ gradient, the FORAM index (FI), as
previously developed and applied in the Caribbean, showed a high correlation with WQ.
Foraminiferan communities also showed distinct regional differences. While the FI did
not predict coral cover, one symbiont-bearing species (Calcarina mayori) was positively
correlated with high algal/low coral cover. Because of the vulnerability of corals to other
disturbances it appears that foraminifera are more specific indicators for WQ. Combined
analysis of the WQ, coral- and foraminiferan community data from this monitoring
program provides important insights into the value of WQ indicators based on individual
species’ density or a combined FORAM index. We consider the future application of this
index in the GBR as beneficial, after refinements in the weighting of individual species.
4-18
Linkages Between Coral Assemblages And Coral-Based Proxies Of Terrestrial
Exposure Along A Cross-Shelf Gradient Of The Great Barrier Reef
Stacy JUPITER* 1,2 , Guy MARION 3 , George ROFF 3 , Meegan HENDERSON 3 , Verena
SCHRAMEYER 3 , Malcolm MCCULLOCH 1 , Ove HOEGH-GULDBERG 3
1 Research School of Earth Science, ARC Centre of Excellence for Coral Reef Studies,
Canberra, Australia, 2 Australian Institute of Marine Science, Townsville, Australia,
3 Centre for Marine Studies, ARC Centre of Excellence for Coral Reef Studies, Brisbane,
Australia
We present a novel approach to assess cross-shelf differences in coral community
structure by linking present day coral assemblages with disturbance histories from sites
within varying proximity to the agricultural region of Mackay (Queensland, Australia). In
March 2006, transects were scored for benthic cover composition at sites along a gradient
of distance offshore from the Pioneer River mouth. We additionally measured multiple
proxies from massive Porites corals (luminescence lines, Ba/Ca, δ15N) collected along
the same transect to assess the frequency and intensity of exposure to terrestrial discharge
and fertilizer-derived nitrogen. High, significant cross-shelf variability in live hard coral
cover was observed. The sites closest to the mainland (Round Top, Keswick, St. Bees)
were characterized by low hard coral cover (≤10%), with no significant differences
among sites. Corals at Round Top Island (5 km offshore) occurred as isolated colonies or
thin veneers. Distinct annual luminescence lines and elevated baseline Ba/Ca (mean = 5.0
μmol/mol) in the core records indicated chronic (sub-annual) exposure to freshwater and
resuspended terrestrial sediment that may have historically prevented reef formation. By
contrast, reef assemblages at Keswick and St. Bees Islands (~33 km offshore) were
categorically different due to the dominance of large stands of macroalgae overgrowing
dead reef matrix. Cores from Keswick Island indicated high exposure to Pioneer River
discharge during extreme flood events (1974, 1991), with bright luminescent lines and
significantly enriched δ15N (12-14‰) reflecting an isotopically distinct lower Pioneer
catchment source (~9‰) combined with further fractionation by phytoplankton blooms.
Scawfell Island (50 km offshore) had high hard coral (22%) and soft coral (35%) cover,
and coral core records indicated little exposure to Pioneer catchment influence. These
results suggest that nearshore reefs adjacent to highly modified catchments may be
particularly vulnerable to phase shifts if they are episodically disturbed by pulses of
nutrient-rich terrestrial runoff.
4-19
Unable To Retrieve Title from Database
Tsuyoshi WATANABE* 1 , Atsushi SUZUKI 2 , Tatsunori KAWASHIMA 1 , Shoshiro
MINOBE 1 , Yolanda AGUILAR 3 , Koji KAMEO 4 , Kayo MINOSHIMA 2 , Ryoji WANI 5 , Hodaka
KAWAHATA 6 , Tomoki KASE 7
1 Natural history Sciences, Hokkaido University, Sapporo, Japan, 2 National institution of
Advanced Industrial Science and Techlology, Tsukuba, Japan, 3 Bureau of Mine and
Geosciences, Philippine, Manila, Philippines, 4 Chiba Univercity, Chiba, Japan, 5 Yokohama
National University, Yokohama, Japan, 6 University of Tokyo, Tokyo, Japan, 7 National Science
Museum, Tokyo, Japan
Global mean temperature and atmospheric CO2 concentration during the early Pliocene warm
period (PWP; 5-3 Ma) were substantially high as much as those predicted for the future climatic
system in 100 years future. The oceanic and atmospheric conditions can be studied in the
context of future global warmth. However, the role of El Nino-Southern Oscillation (ENSO) in
this greenhouse warming remains controversial mainly because of the lack of the information
about seasonal to inter-annual variability in sea surface water in low latitude regions. We found
two well-preserved fossil corals in muddy sand layers of the northern part of Philippians
including this warm period (3.5-3.8Ma). Here, we demonstrate two 35 years coral oxygen
isotopic profiles with monthly resolution in order to investigate seasonal and interannual
characteristics of Pliocene ENSO. In the present day, the anomalies of sea surface temperature
and precipitation were significantly evident in Philippine during El Nino occurring. Significant
attenuations of seasonal amplitude were found in 18O/16O ratios of both two PWP coral
records, which were also detected in the recent corals during modern El Nino events.
4-20
High-precision U-series and 14C Dating Of The Deep-Sea Coral Enallopsammia rostrata
Fanny HOULBREQUE* 1,2 , Brendan ROARK 1 , Robert DUNBAR 1 , Tom GUILDERSON 3 ,
Malcolm MCCULLOCH 4 , Anders MEIBOM 5
1 2
Geological & Environmental Sciences, Stanford University, Stanford, CA, Marine
Environment Laboratory, International Atomic Energy Agency, Monaco, Monaco, 3 Center for
Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory, Livermore, CA,
4
Research School of Earth Sciences, Australian National University, Canberra, Australia,
5
Laboratoire d'Etude de la Matiere Extraterrestre, Museum National d'Histoire Naturelle, Paris,
France
We utilize deep-sea corals in a systematic approach to reconstruct past ocean conditions over
centennial to millennial timescales. As part of this endeavor we present new results on
Enallopsammia rostrata, a pan-oceanic scleractinian species. Here we show that E. rostrata
collected live using the Pisces submersibles from water depths between 480-790 m at three
locations in the Line Islands (~160°W, central Equatorial Pacific) has the potential to act as a
recorder of changes in deep-sea environments over centennial time scales. To improve the
utility of this scleractinian species as a monitor of interior ocean variability, we have applied a
high-precision, low blank technique to measure 230Th and 238U-234U in small amounts (80 ±
10 mg) of modern and near modern calcareous skeletons using MC-ICPMS (Multicollector
Inductively Coupled Plasma Mass Spectrometry). Absolute dated specimens exhibit radial
growth rates from 23-114 µm/yr and vertical extension rates from 0.57 to 1.87 mm/yr. Colony
life spans ranged from 108 ± 5 yrs to 607 ± 6 yrs. The growth rates reported here are similar to
those of other deep-sea scleractinian corals, but with a 2 to 3-fold greater life span for the oldest
samples. Slow growth rates and great longevity make this species especially vulnerable to
disturbances and impacts from climate change and anthropogenic activities. Paired U-series and
14C dating measurements along radial sampling tracks of different colonies of E. rostrata,
allow us to estimate 14C-ventilation rates of the water masses that the corals experienced on
centennial timescales. Our initial results document a centennial periodicity in the 14C
ventilation ages in this region of the Pacific Basin.
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