Spatial and temporal distribution of C37 alkenones in suspended materials in the northern East China Sea

Ko, Tae Wook; Lee, Jun Young; Bae, Si Woong; Lee, Sunghye

doi:10.1016/j.palaeo.2018.01.004

Cited by 8 publications

(3 citation statements)

References 28 publications

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“…This could be interpreted that core F11A was much closer to the pathway of YSWC, benefiting from the nutrient brought by upwelling from the subsurface of the KC (Chen, 1996). Similarly, a modern study in the mud area of the ECS found that C 37 alkenone concentrations in suspended materials were high in the east and very low in the west of the study area, with an obvious chlorophylla boundary along about 126°E (close to the middle core position of this study) (Ko et al, 2018). In addition, high salinity of YSWC water favored coccolithophore growth in core F11A (Xing et al, 2011;Mei et al, 2016), thus resulting in very high alkenone contents (Fig.…”

Section: 22supporting

confidence: 68%

Air-sea interactive forcing on phytoplankton productivity and community structure changes in the East China Sea during the Holocene

Wang

Xiao

Yuan

et al. 2019

Global and Planetary Change

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Phytoplankton productivity and community structure in the East China Sea (ECS) play an important role in marine ecology and carbon cycle, but both have been changing rapidly in response to recent oceanic and atmospheric circulation changes. However, the lack of long-term records of phytoplankton productivity and community structure variability in the region hinders our understanding of natural forcing mechanisms. Here, we use the phytoplankton biomarker (brassicasterol, dinosterol and alkenones) contents as well as the ratios between these biomarkers in three sediment cores from the ECS shelf to reconstruct the spatiotemporal variations of productivity and community of diatoms, dinoflagellates and coccolithophores during the Holocene, respectively. During 9-7 ka, the ECS shelf was characterized by low phytoplankton productivity with low coccolithophore contribution, caused by the oligotrophic condition mainly owing to the restricted Kuroshio Current (KC) intrusion under low sea-level conditions, thus the lack of nutrient input. Phytoplankton productivity generally increased during 7-4.6 ka, in response to the initial intrusion of the Yellow Sea Warm Current (YSWC, a branch of the KC), bringing nutrient from the subsurface KC to the upper layer of the ECS for phytoplankton growth. Phytoplankton productivity continuously increased during 4.6-1 ka, due to an enhanced circulation system (YSWC and Yellow Sea Coastal Current (YSCC)) driven by strong East Asia Winter Monsoon (EAWM). Significantly, high alkenone contents and coccolithophore contribution in the eastern core F11A was associated with its location closer to the warm and saline YSWC, which was suitable for coccolithophore growth. Beyond diagenetic processes which could partly account for higher biomarker contents near core tops, elevated phytoplankton productivity during the last 1 ka might be induced by more nutrient supply from the intensified circulation system driven by enhanced KC and anthropogenic activities. The latter also resulted in high dinoflagellate proportions in all three cores. These temporal and spatial changes of phytoplankton productivity and community structure in the ECS during the Holocene corresponded to different mechanisms by the air-sea interaction, providing insights into distinguishing natural forcing and anthropogenic influences on marine ecology.

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Section: 22supporting

confidence: 68%

Air-sea interactive forcing on phytoplankton productivity and community structure changes in the East China Sea during the Holocene

Wang

Xiao

Yuan

et al. 2019

Global and Planetary Change

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“…The influence of irradiance presents an additional hurdle because there is no robust paleoproxy for irradiance at the depth of alkenone production. Modern surveys demonstrate that alkenone production generally occurs within the upper water column (0–100 m), but the depth of maximum alkenone export production is spatially variable and does not strictly follow in‐situ irradiance profiles (Ko et al., 2018; Lee et al., 2014; Lee & Schneider, 2005; Popp et al., 2006; Wolhowe et al., 2014). Because irradiance decreases exponentially with depth, it is plausible that the average irradiance conditions contributing to alkenone production and the sedimentary ε p signal have changed through time.…”

Section: Discussionmentioning

confidence: 99%

Carbon Isotope Fractionation in Noelaerhabdaceae Algae in Culture and a Critical Evaluation of the Alkenone Paleobarometer

Phelps

Hennon

Dyhrman

et al. 2021

Geochem Geophys Geosyst

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Anthropogenic CO 2 emissions are perturbing the global carbon cycle more rapidly than at any time in the last 66 million years (Zeebe et al., 2016). A key component of the natural carbon cycle is coccolithophores, which modify oceanic dissolved inorganic carbon and alkalinity inventories through photosynthetic carbon fixation and the biogenic production of calcium carbonate plates (Balch et al., 1992). These eukaryotic algae are abundant and widely distributed throughout the global oceans today (

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“…The concentration of C 37 alkenones (“C 37 total,” the concentration of C 37 ketones relative to grams of dry sediment extracted) is positively correlated to primary productivity and surface chlorophyll concentration (Raja & Rosell‐Melé, 2021; Volkman et al., 1995). High C 37 total values may indicate high surface primary productivity among photosynthetic algae and presumably strong upwelling (Bolton et al., 2010; Ko et al., 2018; Rostek et al., 1997; Villanueva et al., 2002).…”

Section: Methodsmentioning

confidence: 99%

Pliocene Weakening of Gradients in Temperature but Not in Productivity in the Eastern Equatorial Pacific

Kimble,

Herbert,

Jones

2024

Paleoceanog and Paleoclimatol

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The modern eastern equatorial Pacific Ocean (EEP) exhibits strong upwelling, producing pronounced gradients in sea surface temperature (SST), nutrient concentration, and biological productivity between 80° and 140°W. During the globally warmer late Pliocene (3.0–3.6 Ma), the EEP may have experienced permanent El Niño‐like conditions, supported by a reduced SST gradient across the equatorial Pacific. However, the weakened east‐west SST gradient has been controversial, with disparate results depending on the proxy used to monitor Western Warm Pool SSTs. We present new Pliocene alkenone‐based SST and paleoproductivity records from four Ocean Drilling Program (ODP) cores spanning an east‐west transect across the EEP, which present an internally consistent picture of SST and productivity gradients in the modern cold tongue, resolved at orbital‐scale variability. Strong agreement between core top reconstructions and satellite estimates indicates that alkenone paleotemperature and paleoproductivity proxies are appropriate for reconstructing Pliocene EEP conditions. The average SST gradient between 90° and 120°W was reduced from the modern 1.8°C gradient to 0.9°C in the late Pliocene. Despite the weakened SST gradient, the surface productivity gradient was stronger during the late Pliocene compared to modern, based on calibrated X‐ray fluorescence biogenic opal and alkenone average accumulation rates. Contrary to modern El Niño SST and productivity patterns, reduced Pliocene surface productivity did not accompany the weakened SST gradient. Instead, strong Pliocene biogenic opal and alkenone concentration accumulation gradients in the eastern EEP suggest that subsurface tilting of the nutricline and thermocline persisted to supply vigorous upwelling of warm but nutrient‐rich subsurface waters in a warmer climate.

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Spatial and temporal distribution of C37 alkenones in suspended materials in the northern East China Sea

Cited by 8 publications

References 28 publications

Air-sea interactive forcing on phytoplankton productivity and community structure changes in the East China Sea during the Holocene

Air-sea interactive forcing on phytoplankton productivity and community structure changes in the East China Sea during the Holocene

Carbon Isotope Fractionation in Noelaerhabdaceae Algae in Culture and a Critical Evaluation of the Alkenone Paleobarometer

Pliocene Weakening of Gradients in Temperature but Not in Productivity in the Eastern Equatorial Pacific

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