Enhanced Particulate Organic Carbon Export at Eddy Edges in the Oligotrophic Western North Pacific Ocean

Shih, Yung‐Yen; Hung, Chin‐Chang; Gong, Gwo‐Ching; Chung, W.-C.; Wang, Yu-Huai; Lee, I-Huan; Chen, Kuo-Shu; Ho, Chuang-Yi

doi:10.1371/journal.pone.0131538

Cited by 37 publications

(49 citation statements)

References 46 publications

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“…Moreover, POC fluxes for this ACME were also in line with estimates made for other eddies, such as enhanced POC fluxes determined at the rim of a CE in the Western Pacific (Shih et al, 2015) or inside a CE in the ETNA (Fig. 8, derived from aOUR data in Karstensen et al, 2015).…”

Section: Oxygen Utilization and Carbon Exportsupporting

confidence: 86%

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

et al. 2016

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Abstract. The occurrence of mesoscale eddies that develop suboxic environments at shallow depth (about 40-100 m) has recently been reported for the eastern tropical North Atlantic (ETNA). Their hydrographic structure suggests that the water mass inside the eddy is well isolated from ambient waters supporting the development of severe near-surface oxygen deficits. So far, hydrographic and biogeochemical characterization of these eddies was limited to a few autonomous surveys, with the use of moorings, underwater gliders and profiling floats. In this study we present results from the first dedicated biogeochemical survey of one of these eddies conducted in March 2014 near the Cape Verde Ocean Observatory (CVOO). During the survey the eddy core showed oxygen concentrations as low as 5 µmol kg −1 with a pH of around 7.6 at approximately 100 m depth. Correspondingly, the aragonite saturation level dropped to 1 at the same depth, thereby creating unfavorable conditions for calcifying organisms. To our knowledge, such enhanced acidity within near-surface waters has never been reported before for the open Atlantic Ocean. Vertical distributions of particulate organic matter and dissolved organic matter (POM and DOM), generally showed elevated concentrations in the surface mixed layer (0-70 m), with DOM also accumulating beneath the oxygen minimum. With the use of reference data from the upwelling region where these eddies are formed, the oxygen utilization rate was calculated by determining oxygen consumption through the remineralization of organic matter. Inside the core, we found these rates were almost 1 order of magnitude higher (apparent oxygen utilization rate (aOUR); 0.26 µmol kg −1 day −1 ) than typical values for the open North Atlantic. Computed downward fluxes for particulate organic carbon (POC), were around 0.19 to 0.23 g C m −2 day −1 at 100 m depth, clearly exceeding fluxes typical for an oligotrophic open-ocean setting. The observations support the view that the oxygen-depleted eddies can be viewed as isolated, westwards propagating upwelling systems of their own, thereby represent re-occurring alien biogeochemical environments in the ETNA.

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Section: Oxygen Utilization and Carbon Exportsupporting

confidence: 86%

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

et al. 2016

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“…At stations I1 and I2, the euphotic zone depth was relatively shallow (∼ 70 m), with more light attenuation from suspended particles, which could be caused by elevated particle production. This finding corresponds to the station locations at the edge of the anticyclonic eddy where particulate organic carbon (POC) fluxes can be 2-4-fold higher than those in adjacent oligotrophic waters (Zhou et al, 2013;Shih et al, 2015). For station I4, the case was similar to I1 and I2, as it was located at the edge of two large anticyclonic eddies (supplement).…”

Section: The Response Of Coccolithophores To Eddies In the South Chinsupporting

confidence: 67%

“…For example, different environmental provinces can shift from a community dominated by normally calcified E. huxleyi type A to one characterized by weakly calcified B/C on the Patagonian Shelf and in the Southern Ocean (Cubillos et al, 2007;Poulton et al, 2011). More heavily calcified morphotypes during low C in winter may be responsible for the seasonal morphotype transition in the Bay of Biscay (Smith et al, 2012). Seasonal variability of E. huxleyi coccolith size has also been observed in the Aegean Sea, which may be due to genotypic or ecophenotypic variation (Triantaphyllou et al, 2010).…”

Section: Carbonate Chemistrymentioning

confidence: 99%

Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

et al. 2016

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Abstract. Coccolithophore contributions to the global marine carbon cycle are regulated by the calcite content of their scales (coccoliths) and the relative cellular levels of photosynthesis and calcification rates. All three of these factors vary between coccolithophore species and with response to the growth environment. Here, water samples were collected in the northern basin of the South China Sea (SCS) during summer 2014 in order to examine how environmental variability influenced species composition and cellular levels of calcite content. Average coccolithophore abundance and their calcite concentration in the water column were 11.82 cells mL−1 and 1508.3 pg C mL−1, respectively, during the cruise. Water samples can be divided into three floral groups according to their distinct coccolithophore communities. The vertical structure of the coccolithophore community in the water column was controlled by the trophic conditions, which were regulated by mesoscale eddies across the SCS basin. The evaluation of coccolithophore-based calcite in the surface ocean also showed that three key species in the SCS (Emiliania huxleyi, Gephyrocapsa oceanica, Florisphaera profunda) and other larger, numerically rare species made almost equal contributions to total coccolith-based calcite in the water column. For Emiliania huxleyi biometry measurements, coccolith size positively correlated with nutrients (nitrate, phosphate), and it is suggested that coccolith length is influenced by light and nutrients through the regulation of growth rates. Larger-sized coccoliths were also linked statistically to low pH and calcite saturation states; however, it is not a simple cause and effect relationship, as carbonate chemistry was strongly co-correlated with the other key environmental factors (nutrients, light).

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“…The magnitude of the increases in total lipid and phytoplankton‐derived lipid fluxes following Nicole is of the same magnitude as the increases in labile lipid fluxes that have been observed at 3,200 m depth at the Bermuda Time Series Site following mesoscale physical forcing of a transient bloom (Conte et al, , ; Table S1). Previous studies have demonstrated that mesoscale ocean features can stimulate production and carbon export to the deep ocean (Conte et al, ; Pedrosa‐Pàmies et al, ; Shih et al, ; Stukel et al, ), but the only prior documented evidence of storm‐induced export of POC to depth is the study of Chen et al () in the oligotrophic northwest Pacific Ocean, where an increase in flux of POC at 125 m depth was observed following an extreme weather event.…”

Section: Discussionmentioning

confidence: 99%

Hurricanes Enhance Labile Carbon Export to the Deep Ocean

Pedrosa-Pàmies

Conte

Weber

et al. 2019

Geophysical Research Letters

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Tropical cyclones (hurricanes) generate intense surface ocean cooling and vertical mixing resulting in nutrient upwelling into the photic zone and episodic phytoplankton blooms. However, their influence on the deep ocean remains unknown. Here we present evidence that hurricanes also impact the ocean's biological pump by enhancing export of labile organic material to the deep ocean. In October 2016, Category 3 Hurricane Nicole passed over the Bermuda Time Series site in the oligotrophic NW Atlantic Ocean. Following Nicole's passage, particulate fluxes of lipids diagnostic of fresh phytodetritus, zooplankton, and microbial biomass increased by 30–300% at 1,500 m depth and 30–800% at 3,200 m depth. Mesopelagic suspended particles following Nicole were also enriched in phytodetrital material and in zooplankton and bacteria lipids, indicating particle disaggregation and a deepwater ecosystem response. Predicted climate‐induced increases in hurricane frequency and/or intensity may significantly alter ocean biogeochemical cycles by increasing the strength of the biological pump.

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Enhanced Particulate Organic Carbon Export at Eddy Edges in the Oligotrophic Western North Pacific Ocean

Cited by 37 publications

References 46 publications

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

Oxygen utilization and downward carbon flux in an oxygen-depleted eddy in the eastern tropical North Atlantic

Coccolithophore responses to environmental variability in the South China Sea: species composition and calcite content

Hurricanes Enhance Labile Carbon Export to the Deep Ocean

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