Late Quaternary sea-surface temperatures in the western Coral Sea: Implications for the growth of the Australian Great Barrier Reef

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 677 ◽  
Author(s):  
K.T. Lawrence ◽  
T.D. Herbert
Keyword(s):  
Great Barrier Reef ◽  
Late Quaternary ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Barrier Reef ◽  
Coral Sea ◽  
Surface Temperatures

Late Quaternary sea-surface temperatures in the western Coral Sea: Implications for the growth of the Australian Great Barrier Reef

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 677-680 ◽  
Author(s):  
K.T. Lawrence ◽  
T.D. Herbert
Keyword(s):  
Great Barrier Reef ◽  
Late Quaternary ◽  
Planktonic Foraminifera ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Barrier Reef ◽  
The Past ◽  
Diagenetic Alteration ◽  
Coral Sea ◽  
Surface Temperatures

Abstract Recent chronostratigraphic evidence suggests that the central Australian Great Barrier Reef formed within the past 780 k.y. Periplatform sediments of the same age recovered from the western Coral Sea record a progressive decrease in the δ18O of planktonic foraminifera to the present. Several investigators have proposed that this trend represents an appreciable late Pleistocene warming (∼4 °C) of ocean surface temperatures, which they posit catalyzed the growth of the Great Barrier Reef. Contrary to this hypothesis, we demonstrate using alkenone paleothermometry (\batchmode \documentclass[fleqn,10pt,legalpaper]{article} \usepackage{amssymb} \usepackage{amsfonts} \usepackage{amsmath} \pagestyle{empty} \begin{document} \(U_{37}^{k{^\prime}}\) \end{document}) on sediments from Ocean Drilling Program (ODP) Site 820 that sea-surface temperatures (SSTs) in the western Coral Sea changed by ∼1.5 °C or less during the past ∼800 k.y. If the central Great Barrier Reef rose in the late Quaternary, it was therefore not due to a warming of SSTs. We explore whether a major moisture balance change and/or diagenetic alteration of calcareous microfossils can explain the higher δ18O values observed at depth in the planktonic δ18O record at ODP Site 820. Our results suggest that diagenesis provides a large isotopic overprint.

Factors affecting the cycling of dimethylsulfide and dimethylsulfoniopropionate in coral reef waters of the Great Barrier Reef

2007 ◽  
Vol 4 (5) ◽  
pp. 310 ◽  
Author(s):  
Graham Jones ◽  
Mark Curran ◽  
Andrew Broadbent ◽  
Stacey King ◽  
Esther Fischer ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Great Barrier Reef ◽  
Coral Bleaching ◽  
Time Of Day ◽  
Sea Surface ◽  
Sea Surface Temperatures ◽  
Barrier Reef ◽  
Magnetic Island ◽  
Surface Temperatures ◽  
Acropora Formosa

Environmental context. Levels of atmospheric dimethylsulfide (DMS) and its oxidation products are reputed to affect the microphysics of clouds and the amount of incoming solar radiation to the ocean. Studies of DMS and its precursor compound dimethylsulfoniopropionate (DMSP) at two inshore fringing coral reefs in the Great Barrier Reef highlight pronounced seasonal, diurnal and tidal variation of these compounds, with dissolved DMS and DMSP significantly correlated with sea surface temperatures (SSTs) up to 30°C. During a coral bleaching episode at one of the reef sites, dissolved DMS concentrations decreased when SSTs exceeded 30°C, a result replicated in chamber experiments with staghorn coral. The results raise interesting questions on the role of these organosulfur substances in corals and whether DMS emissions from coral reefs could have an effect on regional climate in the Great Barrier Reef. Abstract. A study of dissolved dimethylsulfide (DMSw), dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp), and atmospheric dimethylsulfide (DMSa) was carried out at two inshore fringing coral reefs (Orpheus Island and Magnetic Island) in the Great Barrier Reef (GBR) to investigate the variation of these organosulfur substances with season, sea surface temperature, tides, and time of day. Highest concentrations of these organosulfur substances occurred in the summer months at both reefs, with lowest concentrations occurring during winter, suggesting a biological source of these compounds from the reef flats. At the Orpheus Island reef, where more measurements were made, DMSw and DMSPd were significantly correlated with tidal height during the flooding tide over the reef (r = 0.37, P < 0.05; r = 0.58, P < 0.01 respectively), and elevated DMSw and DMSa concentrations generally occurred in the daylight hours, possibly reflecting photosynthetic production of DMSw from the reef flats. Chamber experiments with the staghorn coral Acropora formosa confirmed that corals produce DMSw in the day. DMSw (r = 0.43, P < 0.001) and DMSPd (r = 0.59, P < 0.001) were significantly positively correlated with sea surface temperatures (SST) at the Orpheus Island reef. During severe coral bleaching at the eutrophic Magnetic Island reef in the summer, DMSw concentrations decreased at SSTs greater than 30°C, suggesting that reef production of DMSw decreases during elevated SSTs. This was later confirmed in chamber experiments with Acropora formosa, which showed that when this coral was exposed to temperatures at its bleaching threshold (31°C), decreased production of DMSw occurred. These results suggest that DMS and DMSP in coral zooxanthellae may be functioning as antioxidants, but further experiments are needed to substantiate this.

scholarly journals Great Barrier Reef Degradation, Sea Surface Temperatures, and Atmospheric CO2 Levels Collectively Exhibit a Stochastic Process with Memory

2021 ◽  
Author(s):  
Allan Elnar ◽  
Christianlly Cena ◽  
Christopher Casenas Bernido ◽  
M. Victoria Carpio-Bernido
Keyword(s):  
Stochastic Process ◽  
Great Barrier Reef ◽  
Coral Cover ◽  
Sea Surface ◽  
Atmospheric Co2 ◽  
Sea Surface Temperatures ◽  
Barrier Reef ◽  
Hard Coral ◽  
Co2 Levels ◽  
Hard Coral Cover

Abstract Quantifying ecological memory could be done at several levels from the rate of physiological changes in an ecosystem all the way down to responses at the genetic level. One way of unlocking the information encoded in a collective environmental memory is to examine the recorded time-series data generated by different components of an ecosystem. In this paper, we probe into the case of the Great Barrier Reef (GBR) which is threatened by elevated sea surface temperatures (SST) and ocean acidification attributed to rising atmospheric CO 2 levels. Specifically, we investigate the interrelated dynamics between the degradation of the GBR, SST, and rising atmospheric CO 2 levels, by considering three datasets: (a) the mean percentage hard coral cover of the GBR from the archives of the Australian Institute of Marine Science; (b) SST close to the GBR from the National Oceanic and Atmospheric Administration; and (c) the Keeling curve for atmospheric CO 2 levels measured by the Mauna Loa Observatory. We show that fluctuating observables in these datasets have the same memory behavior described by a non-Markovian stochastic process. All three datasets show a good match between empirical and analytical mean square deviation. An explicit analytical form for the corresponding probability density function is obtained which obeys a modified diffusion equation with a time dependent diffusion coefficient. This study provides a new perspective on the similarities of and interaction between the GBR’s declining hard coral cover, SST, and rising atmospheric CO2 levels by putting all three systems into one unified framework indexed by a memory parameter μ and a characteristic frequency ν . The short-time dynamics of CO2 levels and SST fall in the superdiffusive regime, while the GBR exhibits hyperballistic fluctuation in percent coral cover with the highest values for μ and ν .

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