Characterization of dissolved organic matter in a coral reef ecosystem subjected to anthropogenic pressures (La Réunion Island, Indian Ocean) using multi-dimensional fluorescence spectroscopy

Tedetti, Marc; Cuet, Pascale; Guigue, Catherine; Goutx, Madeleine

doi:10.1016/j.scitotenv.2011.01.058

Cited by 73 publications

(64 citation statements)

References 51 publications

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“…This study shows clearly how fDOM spectral analyses can be used to differentiate water masses according to the degree of influence of SGD in two sites with very different SGD organic matter profiles, consistent with previous work conducted in coral reef environments with allochthonous DOM inputs (Tedetti et al, 2011). Based on our observations, it is clear that groundwater entering Maunalua Bay contains a significant quantity of fDOM with more than double the humification index (HIX) of the receiving Diffuse Zone and Ambient Reef waters ( Figure 6, Table 1), consistent with fDOM from sedimentary and volcanic sources in reef ecosystems (Tedetti et al, 2011).…”

Section: Recommendations For the Use Of Fdom To Track Groundwater Dissupporting

confidence: 91%

“…The elevated levels of nitrate and phosphate found in SGD in many regions of Hawaiʻi (Johnson et al, 2008;Knee et al, 2010;Street et al, 2008) have been implicated as a key factor in coastal eutrophication (Dailer et al, 2010), changes in benthic algal composition Stimson and Larned, 2000) and alteration of nearshore plankton biomass and community structure (Fabricius, 2005;McCook, 1999;Parsons et al, 2008). Despite our conceptualization of SGD as driving eutrophication, we have few studies mapping the distribution of organic matter in the water column of reefs experiencing significant SGD inputs (Tedetti et al, 2011). A key question for the role of SGD in coral ecosystems is how SGD may influence the organic composition of coral reefs, both through allochthonous subsidies and through stimulation of autochthonous productivity.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…The organic matter content of groundwater can vary widely depending on the geological and hydrological factors defining groundwater catchments and biogeochemical processes altering solutes within the subterranean estuary (STE) (Kim et al, 2012). SGD in island systems can be sourced from a variety of different ages and levels of human impact (Knee et al, 2010;Wolanski et al, 2009), and little is known about the characteristics of groundwater organic matter in Pacific islands (Tedetti et al, 2011). SGD passes through the STE, a biogeochemical reactor that is analogous in metabolic complexity to surface estuaries where terrestrial freshwater and recirculated seawater mix, differing markedly with regards to sunlight exposure, residence time and redox conditions.…”

Section: Accepted Manuscriptmentioning

confidence: 99%

“…Analysis of the multivariate spectral characteristics of fDOM by generating an excitation-emission matrix (EEM) from a sample is a cost-effective analysis that requires minimal laboratory training and equipment and can produce a suite of informative data about the organic matter chemistry of the water. In marine ecosystems, the variation in fDOM characteristics has been used to differentiate between a variety of DOM sources including terrestrial (Coble, 1996), algal (Determann et al, 1998), microbial (Stedmon and Markager, 2005) and anthropogenic (Dabestani and Ivanov, 1999;Ferretto et al, A C C E P T E D M A N U S C R I P T (Chen et al, 2003;Helms et al, 2013;Osburn et al, 2013;Tedetti et al, 2011).…”

Section: Accepted Manuscriptmentioning

confidence: 99%

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Fluorescent dissolved organic matter as a multivariate biogeochemical tracer of submarine groundwater discharge in coral reef ecosystems

et al. 2015

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I.M., Fluorescent dissolved organic matter as a multivariate biogeochemical tracer of submarine groundwater discharge in coral reef ecosystems, Marine Chemistry (2015), AbstractIn Hawaiʻi and other Pacific high islands submarine groundwater discharge (SGD) can be a significant and continuous source of solutes to nearshore reefs and may play a key role in the structure and function of benthic coral and algal communities.Identifying SGD sources and linking them to reef biogeochemistry is technically challenging. Here we analyzed spectra of fluorescent dissolved organic matter (fDOM) in coral reefs in the context of a suite of biogeochemical parameters along gradients of SGD to characterize fDOM composition and evaluate the utility of fDOM signatures in tracking groundwater dispersal and transformation. We spatially mapped water column chemistry in Maunalua Bay, O'ahu, Hawaiʻi by collecting 24 water samples in grids at each of two ~0.15 km 2 regions during both high and low tides over a two-day period. We observed clear horizontal gradients in the majority of 15 measured parameters, including inorganic and organic solutes and organic particles that tracked concentrations of conservative SGD tracers (radon, salinity and silicate). Multivariate scanning excitation-emission fluorometry successfully differentiated two distinct groundwater sources and delineated regions of SGD dispersion in each reef from the surrounding water column samples without detectable groundwater. Groundwater was consistently depleted in DOC and enriched in nutrients; although the two SGD sources varied widely in fDOM quantity and fluorophore proportions, indices of humification were consistently elevated in SGD at both sites. Our results provide a robust spectral characterization of fDOM in SGD-influenced coral reefs and indicate the potential for this rapid and cost-effective measurement technique to be useful in tracking SGD dispersal in nearshore ecosystems.

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Section: Recommendations For the Use Of Fdom To Track Groundwater Dissupporting

confidence: 91%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

Section: Accepted Manuscriptmentioning

confidence: 99%

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Fluorescent dissolved organic matter as a multivariate biogeochemical tracer of submarine groundwater discharge in coral reef ecosystems

et al. 2015

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“…Samples for FDOM analyses were stored at 4 • C until analysis (within 1 month), while samples for CDOM absorption analyses were directly measured on a liquid waveguide capillary flow cell (WPI) according to the method of Kowalczuk et al (2013). Excitationemission matrix (EEM) spectra for analysis of FDOM were determined using a Hitachi F-7000 spectrofluorometer (Tedetti et al, 2011). FDOM components were identified by parallel factor analysis (PARAFAC), a statistical decomposition technique used to extract the most representative fluorescent components within EEMs dataset.…”

Section: Fdom and Cdom Analysesmentioning

confidence: 99%

Dissolved Organic Matter Influences N2 Fixation in the New Caledonian Lagoon (Western Tropical South Pacific)

et al. 2018

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Specialized prokaryotes performing biological dinitrogen (N 2 ) fixation ("diazotrophs") provide an important source of fixed nitrogen in oligotrophic marine ecosystems such as tropical and subtropical oceans. In these waters, cyanobacterial photosynthetic diazotrophs are well known to be abundant and active, yet the role and contribution of non-cyanobacterial diazotrophs are currently unclear. The latter are not photosynthetic (here called "heterotrophic") and hence require external sources of organic matter to sustain N 2 fixation. Here we added the photosynthesis inhibitor 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) to estimate the N 2 fixation potential of heterotrophic diazotrophs as compared to autotrophic ones. Additionally, we explored the influence of dissolved organic matter (DOM) on these diazotrophs along a coast to open ocean gradient in the surface waters of a subtropical coral lagoon (New Caledonia). Total N 2 fixation (samples not amended with DCMU) ranged from 0.66 to 1.32 nmol N L −1 d −1 . The addition of DCMU reduced N 2 fixation by >90%, suggesting that the contribution of heterotrophic diazotrophs to overall N 2 fixation activity was minor in this environment. Higher contribution of heterotrophic diazotrophs occurred in stations closer to the shore and coincided with the decreasing lability of DOM, as shown by various colored DOM and fluorescent DOM (CDOM and FDOM) indices. We tested the response of diazotrophs (in terms of nifH gene expression and bulk N 2 fixation rates) upon the addition of a mix of carbohydrates ("DOC" treatment), amino acids ("DON" treatment), and phosphonates and phosphomonesters ("DOP" treatment). While nifH expression increased significantly in Trichodesmium exposed to the DOC treatment, bulk N 2 fixation rates increased significantly only in the DOP treatment. The lack of nifH expression by gammaproteobacteria, in any of the DOM addition treatments applied, questions the contribution of non-cyanobacterial diazotrophs to fixed nitrogen inputs in the New Caledonian lagoon. While the metabolism and ecology of heterotrophic diazotrophs is currently elusive, a deeper understanding of their ecology and relationship with DOM is needed in the light of increased DOM inputs in coastal zones due to anthropogenic pressure.

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The Use of 3‐D Fluorescence and Its Decomposition in Environmental Organic Matter Studies

Mounier

Redon

2018

Encyclopedia of Analytical Chemistry

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Fluorescence spectroscopy is a powerful tool for natural organic matter (NOM) studies. It is used since 1938 by Kalle, and its development was associated to the optical (excitation and emission scanning, excitation correction, grating diffraction, etc.) and computational progresses (memories and processor capacity). The fluorescence principal basis will be recalled and a focus on the 3‐D fluorescence use for environmental purpose will be performed. Fluorophore decomposition and application to river, estuaries, and ocean will be presented and specific techniques such as fluorescence quenching, photobleaching, and chemometric treated. This article intends to give a rapid overview of the possible advances in UV/visible fluorescence spectroscopy.

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Characterization of dissolved organic matter in a coral reef ecosystem subjected to anthropogenic pressures (La Réunion Island, Indian Ocean) using multi-dimensional fluorescence spectroscopy

Cited by 73 publications

References 51 publications

Fluorescent dissolved organic matter as a multivariate biogeochemical tracer of submarine groundwater discharge in coral reef ecosystems

Fluorescent dissolved organic matter as a multivariate biogeochemical tracer of submarine groundwater discharge in coral reef ecosystems

Dissolved Organic Matter Influences N2 Fixation in the New Caledonian Lagoon (Western Tropical South Pacific)

The Use of 3‐D Fluorescence and Its Decomposition in Environmental Organic Matter Studies

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