Impact of an anticyclonic eddy on the summer nutrient and chlorophyll a distributions in the Ulleung Basin, East Sea (Japan Sea)

Kim, Dongseon; Yang, Eun Jin; Kim, Kyung Hee; Shin, Chang-Woong; Park, Jisoo; Yoo, Sinjae; Hyun, Jung‐Ho

doi:10.1093/icesjms/fsr178

Cited by 75 publications

(63 citation statements)

References 34 publications

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“…A similar high C org content as in the UB is rarely found in deep-sea sediment underlying oxic bottom water at depths exceeding 2000 m, except for a Chilean upwelling site (Lee et al, 2008). This high C org content in the UB is mainly associated with the combination of enhanced biological production resulting from the formation of coastal upwelling (Hyun et al, 2009a), enhanced new production in summer (Kwak et al, 2013), occurrence of an intrathermocline eddy resulting in the extraordinary subsurface chlorophyll a maximum (Kim et al, 2012), high C org accumulation rates exceeding 2 g C m −2 year −1 (Lee et al, 2008), and high export production . Consequently, high benthic mineralization resulting from the high C org in the sediment implied that the UB is a biogeochemical hotspot where significant turnover of organic matter and nutrient regeneration occur.…”

Section: The Ub As a Biogeochemical Hotspotmentioning

confidence: 57%

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

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Abstract. Rates and pathways of benthic organic carbon (C org ) oxidation were investigated in surface sediments of the Ulleung Basin (UB) characterized by high C org contents (> 2.5 %, dry wt.) and very high contents of Mn oxides (> 200 µmol cm −3 ) and Fe oxides (up to 100 µmol cm −3 ). The combination of geochemical analyses and independently executed metabolic rate measurements revealed that Mn and Fe reduction were the dominant C org oxidation pathways in the center of the UB, comprising 45 and 20 % of total C org oxidation, respectively. By contrast, sulfate reduction was the dominant C org oxidation pathway, accounting for 50 % of total C org mineralization in sediments of the continental slope. The relative significance of each C org oxidation pathway matched the depth distribution of the respective electron acceptors. The relative importance of Mn reduction for C org oxidation displays saturation kinetics with respect to Mn oxide content with a low half-saturation value of 8.6 µmol cm −3 , which further implies that Mn reduction can be a dominant C org oxidation process even in sediments with lower MnO 2 content as known from several other locations. This is the first report of a high contribution of manganese reduction to C org oxidation in offshore sediments on the Asian margin. The high manganese oxide content in the surface sediment in the central UB was maintained by an extreme degree of recycling, with each Mn atom on average being reoxidized ∼ 3800 times before permanent burial. This is the highest degree of recycling so far reported for Mn-rich sediments, and it appears linked to the high benthic mineralization rates resulting from the high C org content that indicate the UB as a biogeochemical hotspot for turnover of organic matter and nutrient regeneration.

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Section: The Ub As a Biogeochemical Hotspotmentioning

confidence: 57%

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

et al. 2017

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“…A few hypotheses have been suggested as the main cause of the high primary productivity in the UB. These include physical processes such as coastal upwelling and mesoscale eddies [Hyun et al, 2009;Yoo and Park, 2009;Kim et al, 2012;Lim et al, 2012]. A recent study that compared summer primary productivity in the UB with that in the subtropical western Pacific and the East China Sea suggested that the relatively high rates of primary productivity in the UB is supported by increased nitrate (NO 3 ) supply from nutrient-rich deeper waters to the euphotic zone because of the shallow pycnocline in summer [Kwak et al, 2013a].…”

Section: Introductionmentioning

confidence: 99%

Summer primary productivity and phytoplankton community composition driven by different hydrographic structures in the East/Japan Sea and the Western Subarctic Pacific

et al. 2014

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The East/Japan Sea (EJS) is a highly productive marginal sea in the northwest Pacific, consisting of three basins (Ulleung Basin: UB, Yamato Basin: YB, and Japan Basin: JB). To find causes of the reportedly high primary productivity in summer in the EJS, especially in the UB, we measured primary productivity, phytoplankton composition, and other environmental variables. The water column was strongly stratified in the EJS compared with the Western Subarctic Pacific (WSP). Integrated primary productivity was two times higher in the EJS (612 mg C m 22 d 21 ) than in the WSP (291 mg C m 22 d 21 ). The vertical distributions of physicochemical and biological factors confirmed that production in the subsurface chlorophyll maximum layer in the study regions was an important factor regulating primary productivity within the water column. While picoplankton (<2.7 mm) dominated in the WSP, JB, and YB, micro/nanoplankton (2.7 mm) dominated in the UB. Contribution by picoplankton to total biomass and primary productivity in the UB was significantly lower than in the other regions. CHEMTAX analysis using marker pigments showed that diverse phytoplankton groups inhabited the study regions. Cluster and canonical correspondence analyses showed high correlation between the spatial variation in phytoplankton assemblages with the water mass properties mainly represented by water temperature and nitrate concentration. Overall, our results suggest that the hydrographic structure of water column in the study region is an important controlling factor of the biomass and productivity of phytoplankton as well as their diversity in size and taxonomic groups.

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“…7). It is probable that these increases are the maximum surface expression developed below the surface, as reported for ITEs in other oceanic regions (McGillicuddy et al, 2007;Kim et al, 2011). In the JFA, high surface Chl-a concentrations have been detected reaching values of ~2 mg m -3 in AS island and ~1 mg m -3 in the RC-SC islands (Pizarro et al, 2006).…”

Section: Discussionmentioning

confidence: 76%

Intrathermocline eddies at the Juan Fernandez Archipelago, southeastern Pacific Ocean

Andrade

Hormazábal

Combes

2014

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ABSTRACT. Regional Ocean Modeling System (ROMS) results, combined with chlorophyll-a (Chl-a) and satellite altimetry information as well as information from oceanographic cruises were analyzed to identify interactions between intrathermocline eddies (ITEs) and the Juan Fernández Archipelago (JFA), and discuss their potential impact on surface Chl-a concentrations. The JFA is located off the coast of central Chile (33°S), and is composed of three main islands: Robinson Crusoe (RC), Alejandro Selkirk (AS) and Santa Clara (SC). Results indicate that the surface and subsurface anticyclonic eddies that interact with the JFA are formed primarily within the coastal transition zone between 33° and 39°S. ITEs are present within the JFA region with a semiannual frequency, mainly during the austral autumn, and have a weak surface expression in relation to the adjacent surface eddies, with a slow displacement (1.16 to 1.4 km d -1 ) in a northwest direction and a coherent structure for periods of ≥1 year. During the ITEs' interaction with RC-SC islands and an adjacent seamount, a slight (prominent) thermocline deflection of the upper limit (lower) was observed. The horizontal extent (~70-100 km) was greater than the internal Rossby deformation radius and the average vertical extent was ~400 m. The interaction between the weak surface expression of ITEs, identified with satellite altimetry, and the JFA persisted during autumn for nine weeks until reaching the winter period. Approximately one month after the beginning of the interaction between ITEs and the islands, increases in surface Chl-a associated with the eddy were observed, with values up to three times higher than adjacent oceanic waters. Keywords: intrathermocline eddies, Juan Fernández Archipelago, southeastern Pacific Ocean. Remolinos intratermoclina en el Archipiélago Juan Fernández,Océano Pacífico suroriental RESUMEN. Se analizaron los resultados de un modelo oceánico regional (ROMS), combinado con información de clorofila-a (Clo-a) y altimetría satelital, además de información proveniente de cruceros oceanográficos, para identificar la interacción entre los remolinos intratermoclina (ITEs) y el Archipiélago Juan Fernández (AJF), y discutir su potencial impacto sobre las concentraciones de Clo-a superficial. El AJF se encuentra ubicado frente a la costa central de Chile (33°S), y está conformado por las islas Robinson Crusoe, Santa Clara y Alejandro Selkirk. Los resultados indican que los remolinos anticiclónicos superficiales y subsuperficiales que interactúan con el AJF se forman principalmente en la zona de transición costera entre 33° y 39°S. Los ITEs se presentan en la región del AJF con una frecuencia semianual, principalmente durante el período de otoño austral, y poseen una débil expresión superficial respecto de los remolinos superficiales adyacentes, un lento desplazamiento (1,16-1,4 km d -1) con dirección noroeste y una estructura coherente por períodos ≥1 año. Durante la interacción de los ITEs con las islas RC-SC y el monte submarino adyacente, se ob...

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Impact of an anticyclonic eddy on the summer nutrient and chlorophyll a distributions in the Ulleung Basin, East Sea (Japan Sea)

Cited by 75 publications

References 34 publications

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Manganese and iron reduction dominate organic carbon oxidation in surface sediments of the deep Ulleung Basin, East Sea

Summer primary productivity and phytoplankton community composition driven by different hydrographic structures in the East/Japan Sea and the Western Subarctic Pacific

Intrathermocline eddies at the Juan Fernandez Archipelago, southeastern Pacific Ocean

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