Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Catalá, Teresa S.; Álvarez‐Salgado, Xosé Antón; Otero, Jaime; Iuculano, Francesca; Companys, B.; Horstkotte, Burkhard; Romera‐Castillo, Cristina; Nieto‐Cid, Mar; Latasa, Mikel; Morán, Xosé Anxelu G.; Gasol, Josep M.; Marrasé, Cèlia; Stedmon, Colin A.; Reche, Isabel

doi:10.1002/lno.10281

Cited by 53 publications

(83 citation statements)

References 110 publications

(225 reference statements)

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“…The four PARAFAC fluorescent components identified in the surface waters of the NZSSO have also been reported in other oceanic regions (Murphy et al, 2008;Jorgensen et al, 2011;D'Sa et al, 2014;Catalá et al, 2015Catalá et al, , 2016 including the Southern Ocean (Wedborg et al, 2007;Nelson and Gauglitz, 2016). The relative concentrations and latitudinal distribution patterns of the four components however, appeared to be influenced by physical and biological processes along the NZSSO.…”

Section: Fdom Distribution Along the Transectsupporting

confidence: 62%

“…In contrast, protein-like fluorescent material display narrower peaks typically in the UV spectral region with characteristics similar to tryptophan and tyrosine-like amino acids likely derived from marine planktonic organisms or bacterial activity (Coble, 1996;Yamashita and Tanoue, 2003;Stedmon and Markager, 2005). Due to the overlapping contribution of the various fluorophores in the EEMs, statistical approaches such as parallel factor analysis (PARAFAC) are commonly used to decompose CDOM EEMs data into their individual fluorescent components that have provided a more quantitative and qualitative assessment of its composition (Stedmon et al, 2003;Stedmon and Bro, 2008) in various oceanic regions (Murphy et al, 2008;Jorgensen et al, 2011;Catalá et al, 2015Catalá et al, , 2016D'Sa et al, 2016), including the Southern Ocean (Wedborg et al, 2007;Nelson and Gauglitz, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Surface Gradients in Dissolved Organic Matter Absorption and Fluorescence Properties along the New Zealand Sector of the Southern Ocean

D’Sa

Kim

2017

Front. Mar. Sci.

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The Southern Ocean plays a critical role in the global carbon cycle; dissolved organic matter (DOM), a component in the carbon cycling, can be characterized optically. Sea surface chromophoric dissolved organic matter (CDOM) absorption and fluorescence properties were examined in the New Zealand sector of the Southern Ocean (NZSSO) along a transect encompassing various hydrographic fronts associated with the Antarctic Circumpolar Current (ACC) during summer. Phytoplankton chlorophyll, dissolved organic carbon (DOC) and CDOM absorption were observed to be most elevated off the New Zealand shore and then decreased to low values [chlorophyll: 0.21 ± 0.06 mg m −3 ; DOC: 54.19 ± 4.02 µM, and CDOM absorption coefficient at 325 nm (a g 325): 0.097 ± 0.061 m −1 ] between the Subtropical (STF) and Antarctic Polar (APF) Fronts. Increases in phytoplankton biomass and DOC concentrations between the fronts were associated with meanders or eddies observed in satellite sea surface salinity and chlorophyll imagery. Overall, CDOM absorption was the dominant contributor to total absorption at 443 nm with implications for ocean color. Beyond the APF in the Antarctic Zone, an elevated chlorophyll band likely associated with upwelled waters transitioned to low chlorophyll in the summer ice edge zone that influenced DOM optical properties. A latitudinal increase in a g 325 and corresponding decrease in spectral slope S (µm −1 ) poleward from the STF could be due to a combination of factors including, decreasing CDOM photooxidation, upwelling of high-CDOM waters or bacterial CDOM production in the Antarctic Zone. Parallel factor analysis (PARAFAC) of fluorescence spectra identified two protein-like (C1 and C2) and two humic-like (C3 and C4) components common in the global ocean. a g 325 and the humic-like C4 fluorescent component were positively correlated to chlorophyll, indicating biological control. Surface distribution of the protein-like C1 and C2 and the marine humic-like C3 components showed patterns that appeared to be influenced by both physical and biological processes. This study provides insights into surface CDOM optical properties and its transformation along a complex topographically influenced sector of the Southern Ocean that could be used to trace changes linked to the meridional overturning circulation.

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Section: Fdom Distribution Along the Transectsupporting

confidence: 62%

Section: Introductionmentioning

confidence: 99%

Surface Gradients in Dissolved Organic Matter Absorption and Fluorescence Properties along the New Zealand Sector of the Southern Ocean

D’Sa

Kim

2017

Front. Mar. Sci.

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“…Catalá et al (2016) demonstrated that the global depth distribution tryptophan-like FDOM component has a local maximum associated with a chlorophyll a maximum. The linkage between protein-like components and chlorophyll a concentration shown qualitatively in the global ocean by Stedmon and Nelson (2015) and Catalá et al (2016) was previously confirmed quantitatively in mesocosm studies, for example, Romera-Castillo et al (2010), which indicated that phytoplankton excreted tryptophan-like fluorophores, and tryptophan-like component concentration has been related to primary production (Brym et al, 2014). In situ quantitative correlation between chlorophyll a concentrations and fluorescence intensity of the protein-like FDOM fraction has been observed and documented recently.…”

Section: Distribution Of Fdom Components In the Ocean And Their Depenmentioning

confidence: 99%

“…The distribution pattern of the main FDOM components with depth in the global oceans' biogeochemical provinces is significantly different for humic-like and protein-like FDOM (Stedmon and Nelson, 2015;Catalá et al, 2016). The intensity of the humic-like FDOM fraction is usually higher close to continental margins and significantly depleted in the centers of subtropical gyres (Murphy et al, 2008;Jør-gensen et al, 2011;Kowalczuk et al, 2013).…”

Section: Distribution Of Fdom Components In the Ocean And Their Depenmentioning

confidence: 99%

“…The intensity of the humic-like FDOM fraction is usually higher close to continental margins and significantly depleted in the centers of subtropical gyres (Murphy et al, 2008;Jør-gensen et al, 2011;Kowalczuk et al, 2013). The fluorescence of humic-like DOM fractions is low in the surface layer and rapidly increases with depth, reaching a constant high level below 200 m. Protein-like FDOM fluorescence intensity usually increases toward the open ocean and the highest intensity is observed in the surface waters, rapidly decreasing with depth, reaching a constant low level below the epipelagic layer (Jørgensen et al, 2011;Kowalczuk et al, 2013;Catalá et al, 2016). Such profiles indicate that amino-acid-like DOM is linked to surface water production.…”

Section: Distribution Of Fdom Components In the Ocean And Their Depenmentioning

confidence: 99%

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Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

et al. 2018

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Abstract. Optical properties of chromophoric (CDOM) and fluorescent dissolved organic matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June-July 2013, 2014, and 2015. The CDOM absorption coefficient at 350 nm, a CDOM (350) showed significant interannual variation (T test, p < 0.00001). In 2013, the highest average a CDOM (350) values (a CDOM (350) = 0.30 ± 0.12 m −1 ) were observed due to the influence of cold and low-salinity water from the Sørkapp Current (SC) in the southern part of the West Spitsbergen Shelf. In 2014, a CDOM (350) values were significantly lower (T test, p < 0.00001) than in 2013 (average a CDOM (350) = 0.14 ± 0.06 m −1 ), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (average a CDOM (350) = 0.19 ± 0.05 m −1 ) was observed. In situ measurements of three FDOM components revealed that fluorescence intensity of protein-like FDOM dominated in the surface layer of the Nordic Seas. Concentrations of marine and terrestrial humic-like DOM were very low and distribution of those components was generally vertically homogenous in the upper ocean (0-100 m). Fluorescence of terrestrial and marine humic-like DOM decreased in surface waters (0-15 m) near the sea ice edge due to dilution of oceanic waters by sea ice meltwater. The vertical distribution of protein-like FDOM was characterized by a prominent subsurface maximum that matched the subsurface chlorophyll a maximum and was observed across the study area. The highest protein-like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the proteinlike fluorescence and chlorophyll a fluorescence (R 2 = 0.65, p < 0.0001, n = 24 490), which suggests that phytoplankton was the primary source of protein-like DOM in the Nordic Seas and West Spitsbergen Shelf waters. Observed variability in selected spectral indices (spectral slope coefficient, S 300-600 , carbon-specific CDOM absorption coefficient at 254 and 350 nm, SUVA 254 , a * CDOM (350)) and the nonlinear relationship between CDOM absorption and the spectral slope coefficient also indicate a dominant marine (autochthonous) source of CDOM and FDOM in the study area. Further, our data suggest that a CDOM (350) cannot be used to predict dissolved organic carbon (DOC) concentrations in the study region; however the slope coefficient (S 300-600 ) shows some promise in being used.

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Chromophoric and fluorescent dissolved organic matter in and above the oxygen minimum zone off Peru

Loginova

Thomsen

Engel

2016

J. Geophys. Res. Oceans

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As a result of nutrient upwelling, the Peruvian coastal system is one of the most productive regions in the ocean. Sluggish ventilation of intermediate waters, characteristic for the Eastern Tropical South Pacific (ETSP) and microbial degradation of a high organic matter load promotes deoxygenation at depth. Dissolved organic matter (DOM) plays a key role in microbial respiration and carbon cycling, but little is known on DOM distribution and cycling in the ETSP. DOM optical properties give important insights on DOM sources, structure and biogeochemical reactivity. Here, we present data and a conceptual view on distribution and cycling of chromophoric (CDOM) and fluorescent (FDOM) DOM in and above the oxygen minimum zone (OMZ) off Peru. Five fluorescent components were identified during PARAFAC analysis. Highest intensities of CDOM and of the amino acid‐like fluorescent component (C3) occurred above the OMZ and coincided with maximum chl a concentrations, suggesting phytoplankton productivity as major source. High intensities of a marine humic‐like fluorescent component (C1), observed in subsurface waters, indicated in situ microbial reworking of DOM. FDOM release from inner shelf sediment was determined by seawater analysis and continuous glider sensor measurement and included a humic‐like component (C2) with a signature typical for terrestrially derived humic acids. Upwelling supplied humic‐like substances to the euphotic zone. Photo‐reactions were likely involved in the production of a humic‐like fluorescent component (C5). Our data show that variable biological and physical processes need to be considered for understanding DOM cycling in a highly dynamic coastal upwelling system like the ETSP off Peru.

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Drivers of fluorescent dissolved organic matter in the global epipelagic ocean

Cited by 53 publications

References 110 publications

Surface Gradients in Dissolved Organic Matter Absorption and Fluorescence Properties along the New Zealand Sector of the Southern Ocean

Surface Gradients in Dissolved Organic Matter Absorption and Fluorescence Properties along the New Zealand Sector of the Southern Ocean

Characteristics of chromophoric and fluorescent dissolved organic matter in the Nordic Seas

Chromophoric and fluorescent dissolved organic matter in and above the oxygen minimum zone off Peru

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