Enhancement of regional variations in salinity and temperature in a coral reef lagoon, New Caledonia

Ouillon, Sylvain; Douillet, Pascal; Fichez, Renaud; Panche, Jean-Yves

doi:10.1016/j.crte.2005.08.005

Cited by 31 publications

(16 citation statements)

References 13 publications

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“…Fig. 2a Interannual salinity and SST variations in the Southwestern tropical Pacific are linked to ENSO (Gouriou and Delcroix, 2002;Ouillon et al, 2005). Thus, SST covariant changes in SSS (and d 18 O sw ) occur on seasonal and interannual time scales.…”

Section: Tahiti French Polynesiamentioning

confidence: 95%

Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)

Cahyarini

Pfeiffer

Timm

et al. 2008

Geochimica et Cosmochimica Acta

107

166

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We compare several statistical routines that may be used to calculate d 18 O sw and SSS from paired coral Sr/Ca and d 18 O measurements. Typically, the d 18 O coral -SST relationship is estimated by linear regression of coral d 18 O vs. SST. If this method is applied, evidence should be given that at a particular site SST and SSS do not co-vary. In the tropical oceans, SST and d 18 O sw (SSS) often co-vary, and this will bias the estimate of the regression slope of d 18 O coral -SST. Using a stochastic model, we show that covariance leads to a bias in the coefficients of the univariate regression equations. As the slope of the d 18 O coral -SST relationship has known, we propose to insert this value for c 1 in the regression models. This requires that the constants of the regression equations are removed. To omit the constants, we propose to center the regression equations (i.e., to remove the mean values from the variables). The statistical error propagation is calculated to assess our ability to resolve past variations in d 18 O sw (SSS). At Tahiti, we find that the combined analytical uncertainties of coral d 18 O and Sr/Ca equal the amplitude of the seasonal cycle of d 18 O sw (SSS). Therefore, we cannot resolve the seasonal cycle of SSS at Tahiti. At Timor, the error of reconstructed d 18 O sw (SSS) is lower than the magnitude of seasonal variations of d 18 O sw (SSS), and the seasonal cycle of d 18 O sw (SSS) can be resolved.

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Section: Tahiti French Polynesiamentioning

confidence: 95%

Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)

Cahyarini

Pfeiffer

Timm

et al. 2008

Geochimica et Cosmochimica Acta

107

166

View full text Add to dashboard Cite

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“…However, there was a clear increase in Chl-a concentration regionally, indicating that there was an important effect from ENSO on the Venezuelan coast. Westmacott et al (2000) and Ouillon et al (2005) reported that large amounts of precipitation and low salinity are possibly the consequence of the "cold phase" of ENSO, known as "La Niña" and asserted that a decrease in salinity concentration is the second most common trigger for coral reef bleaching.…”

Section: Discussionmentioning

confidence: 99%

Massive bleaching of coral reefs induced by the 2010 ENSO, Puerto Cabello, Venezuela

Mónaco

Haiek

Narciso

et al. 2012

RBT

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El Niño Southern Oscillation (ENSO) has generated global coral massive bleaching. The aim of this work was to evaluate the massive bleaching of coral reefs in Puerto Cabello, Venezuela derived from ENSO 2010. We evaluated the bleaching of reefs at five localities both at three and five meter depth. The coral cover and densities of colonies were estimated. We recorded living coral cover, number and diameter of bleached and nonbleached colonies of each coral species. The colonies were classified according to the proportion of bleached area. Satellite images (Modis Scar) were analyzed for chlorophyll-a concentration and temperature in August, September, October and November from 2008-2010. Precipitation, wind speed and air temperature information was evaluated in meteorological data for 2009 and 2010. A total of 58.3% of colonies, belonging to 11 hexacoral species, were affected and the greatest responses were observed in Colpophyllia natans, Montastraea annularis and Montastraea faveolata. The most affected localities were closer to the mainland and had a bleached proportion up to 62.73±36.55%, with the highest proportion of affected colonies, whereas the farthest locality showed 20.25±14.00% bleached and the smallest proportion. The salinity in situ varied between 30 and 33ppm and high levels of turbidity were observed. According to the satellite images, in 2010 the surface water temperature reached 31ºC in August, September and October, and resulted higher than those registered in 2008 and 2009. Regionally, chlorophyll values were higher in 2010 than in 2008 and 2009. The meteorological data indicated that precipitation in November 2010 was three times higher than in November 2009. Massive coral bleaching occurred due to a three month period of high temperatures followed by one month of intense ENSO-associated precipitation. However, this latter factor was likely the trigger because of the bleaching gradient observed. Rev. Biol. Trop. 60 (2): 527-538. Epub 2012 June 01.

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“…The OC3 Modis algorithm (1) uses 3 spectral bands at 443, 488 and 551 nm to determine chl a concentration (Chl). 4 (2) where R=log 10 (max(R 443 ,R 488 )/R 551 ), for a chl a range between 0.015 and 64 mg/m 3 .…”

Section: Evaluation Of the Algorithmsmentioning

confidence: 99%

“…Coral reef lagoon systems are very sensitive to anthropogenic (nutrients, mining) perturbations [1] as well as to longterm climatic changes which are amplified in lagoons [2]. Sea surface chlorophyll is a proxy of phytoplankton biomass and is a direct integrator for the nutrient status of water masses and chlorophyll monitoring by satellite will greatly expand our knowledge of the functioning of coral reef lagoons [3].…”

Section: Introductionmentioning

confidence: 99%

MODIS/Aqua chlorophyll monitoring of the New Caledonia lagoon during the 2008 La Nina event

et al. 2008

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Tropical oligotrophic coral reef lagoons are areas of high biodiversity. Chlorophyll concentration, a proxy for phytoplankton biomass and primary production, is useful to monitor the carbon balance in the context of the climate change and to validate simulations by coupled biogeochemical models. Chlorophyll monitoring by Aqua/MODIS is examined on the large tropical oligo-to mesotrophic lagoon of New Caledonia (23,900 km 2 ). The classical OC3 algorithm developed for MODIS can only be applied in deep waters. In shallow water, when the water is clear with a weak attenuation, the bottom reflectance influences the surface reflectance and then induces an error in the chlorophyll determination. Here, a new OC3-type polynom, relating satellite reflectance ratios and chlorophyll, was determined from bio-optical data collected during a cruise (Valhybio) on the R/V Alis in the frame of the Programme National de Télédétection Spatiale. From the 22th of March to the 9 th of April, data were collected during two surveys of the same network. A total of 170 in situ bio-optical measurements in the South Western and South lagoons of New Caledonia were obtained, within a 2 weeks interval (70 non-cloudy match-ups). Four Modis images were acquired during this cruise with moderate to good atmospheric conditions. The new polynom gives a RMS of 14.8% and a MNB of -9% and gives a better representation of the "true" water column chlorophyll concentration of the New Caledonia lagoon.

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Enhancement of regional variations in salinity and temperature in a coral reef lagoon, New Caledonia

Cited by 31 publications

References 13 publications

Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)

Reconstructing seawater δ18O from paired coral δ18O and Sr/Ca ratios: Methods, error analysis and problems, with examples from Tahiti (French Polynesia) and Timor (Indonesia)

Massive bleaching of coral reefs induced by the 2010 ENSO, Puerto Cabello, Venezuela

MODIS/Aqua chlorophyll monitoring of the New Caledonia lagoon during the 2008 La Nina event

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