scholarly journals The influence of episodic flooding on pelagic ecosystem in the East China Sea

2016 ◽  
Author(s):  
Chung-Chi Chen ◽  
Gwo-Ching Gong ◽  
Wen-Chen Chou ◽  
Chih-Ching Chung ◽  
Chih-Hao Hsieh ◽  
...  
Keyword(s):  
East China Sea ◽  
East China ◽  
Community Respiration ◽  
The East China Sea ◽  
Pelagic Ecosystem ◽  
Mean Values ◽  
Chl A ◽  
China Sea ◽  
The Mean ◽  
Flooding Period

Abstract. This study was designed to determine the effects of flooding on pelagic ecosystem in the East China Sea (ECS), especially on plankton community respiration (CR). In July 2010, a flood occurred in the Changjiang River. As a comparison, a variety of both abiotic and biotic parameters were monitored, as well as in July 2009, a non-flooding period. During the flooding, the Changjiang diluted water (CDW) zone covered almost two thirds of the ECS, which was approximately six times that of the non-flooding period. The mean nitrate concentration was higher in 2010 (6.2 μM) than in 2009 (2.0 μM). However, during the 2010 flood, the mean values of Chl a and bacterial biomass were only slightly higher or even lower than in 2009. However, the CR was still higher in 2010 than in 2009, with mean values of 105.6 and 73.2 mg C m−3 d−1, respectively. The higher CR in 2010 could be attributed to vigorous plankton metabolic activities, especially phytoplankton, at stations in the CDW zone, which were not characterized by low SSS in 2009. In addition, zooplankton might be another important component contributing to the high CR rate observed in 2010. Furthermore, there was a significant amount of fCO2 drawdown in the 2010 flood. These results suggest that the flood in 2010 had a significant effect on the carbon balance in the ECS. This effect might become more pronounced in the future, as extreme rainfall events and flooding magnitudes are predicted to increase globally due to climate change.

scholarly journals The influence of episodic flooding on a pelagic ecosystem in the East China Sea

2017 ◽  
Vol 14 (10) ◽  
pp. 2597-2609 ◽  
Author(s):  
Chung-Chi Chen ◽  
Gwo-Ching Gong ◽  
Wen-Chen Chou ◽  
Chih-Ching Chung ◽  
Chih-Hao Hsieh ◽  
...  
Keyword(s):  
East China Sea ◽  
Extreme Rainfall ◽  
Sea Surface Salinity ◽  
East China ◽  
Community Respiration ◽  
The East China Sea ◽  
Pelagic Ecosystem ◽  
Surface Salinity ◽  
China Sea ◽  
Flooding Period

Abstract. This study was designed to determine the effects of flooding on a pelagic ecosystem in the East China Sea (ECS) with a focus on plankton activity and plankton community respiration (CR). In July 2010, a flood occurred in the Changjiang River. As a comparison, a variety of abiotic and biotic parameters were monitored during this flooding event and during a non-flooding period (July 2009). During the flood, the Changjiang diluted water (CDW) zone covered almost two-thirds of the ECS, which was approximately 6 times the area covered during the non-flooding period. The mean nitrate concentration was 3-fold higher during the 2010 flood (6.2 vs. 2.0 µM in 2009). CR was also higher in the 2010 flood: 105.6 mg C m−3 d−1 vs. only 73.2 mg C m−3 d−1 in 2009. The higher CR in 2010 could be attributed to phytoplankton respiration, especially at stations in the CDW zone that were not previously characterized by low sea surface salinity in 2009. In addition, zooplankton (> 330 µm) were another important component contributing to the high CR rate observed during the 2010 flood; this was a period also associated with a significant degree of fCO2 drawdown. These results collectively suggest that the 2010 flood had a significant effect on the carbon balance in the ECS. This effect might become more pronounced in the future, as extreme rainfall and flooding events are predicted to increase in both frequency and magnitude due to climate change.

scholarly journals Effects of flooding on organic carbon consumption in the East China Sea

2015 ◽  
Vol 12 (7) ◽  
pp. 5609-5639 ◽  
Author(s):  
C.-C. Chen ◽  
G.-C. Gong ◽  
W.-C. Chou ◽  
C.-C. Chung ◽  
F.-K. Shiah ◽  
...  
Keyword(s):  
East China Sea ◽  
Sea Surface Salinity ◽  
East China ◽  
Community Respiration ◽  
The East China Sea ◽  
Surface Salinity ◽  
Mean Values ◽  
China Sea ◽  
Flood Period ◽  
The Mean

Abstract. This study was designed to determine the effects of flooding on plankton community respiration (CR) in the East China Sea (ECS). In July 2010, a devastating flood occurred in the Changjiang River; the mean monthly discharge was 60 527 m3 s−1. To compare, the variables were also examined in the low riverine flow of July 2009 (33 955 m3 s−1). During the flooding, the Changjiang diluted water (CDW) zone, the sea surface salinity (SSS) was ≤ 31 psu, covering almost two thirds of the ECS, which was approximately six times that in the non-flooding period. The mean nitrate concentration was higher in 2010 (6.2 μM) than in 2009 (2.0 μM). However, in the 2010 flood, the mean values of Chl a and the bacterial biomass were only slightly higher or even lower than in 2009. Surprisingly, however, the CR was still higher in the flood period than in the non-flood period, with mean values of 105.6 and 73.2 mg C m−3 d−1, respectively. The higher CR in 2010 could be attributed to vigorous plankton activities, especially phytoplankton, at stations in the CDW zone, which were not mostly covered by low SSS in 2009. There was a huge amount of fCO2 drawdown in the 2010 flood. These results suggested that the devastating flood in 2010 had a significant effect on the carbon balance in the ECS. This effect might become more pronounced as extreme rainfall events and flooding magnitudes increase dramatically throughout the world.

scholarly journals Importance of planktonic community respiration on the carbon balance of the East China Sea in summer

2006 ◽  
Vol 20 (4) ◽  
pp. n/a-n/a ◽  
Author(s):  
Chung-Chi Chen ◽  
Kuo-Ping Chiang ◽  
Gwo-Ching Gong ◽  
Fuh-Kwo Shiah ◽  
Chun-Mao Tseng ◽  
...  
Keyword(s):  
East China Sea ◽  
Carbon Balance ◽  
East China ◽  
Community Respiration ◽  
The East China Sea ◽  
China Sea ◽  
Planktonic Community

scholarly journals The large variation in organic carbon consumption in spring in the East China Sea

2012 ◽  
Vol 9 (11) ◽  
pp. 16533-16564
Author(s):  
C.-C. Chen ◽  
G.-C. Gong ◽  
F.-K. Shiah ◽  
W.-C. Chou ◽  
C.-C. Hung
Keyword(s):  
Organic Carbon ◽  
East China Sea ◽  
Phytoplankton Growth ◽  
East China ◽  
Community Respiration ◽  
Changjiang River ◽  
Carbon Consumption ◽  
The East China Sea ◽  
China Sea ◽  
The Changjiang River

Abstract. A tremendous amount of organic carbon respired by planktonic communities has been found in summer in the East China Sea (ECS), and this rate has been significantly correlated with fluvial discharge from the Changjiang River. However, data related to this issue in other seasons have rarely been collected. To evaluate and reveal the potential controlling mechanism of organic carbon consumption in spring in the ECS, research using stations covering almost the entire ECS shelf was conducted in the spring of 2009 and 2010. During both periods, the fluvial discharges were similar, and these rates were comparable to high riverine flow in summer. Interestingly, planktonic community respiration (CR) varied widely in both springs; in 2009, the level of CR was double that of 2010, with mean (± SD) values of 111.7 (± 76.3) and 50.7 (± 62.9) mg C m−3 d−1, respectively. The CR was positively linearly regressed with concentrations of particulate organic carbon and/or chlorophyll a (Chl a) in 2009 (all p< 0.01). These results suggest that the rate was dependent on planktonic activities, especially that of phytoplankton, in 2009. During this period, phytoplankton growth flourished due to allochthonous nutrients discharged from the Changjiang River. Furthermore, higher phytoplankton growth leaded to the absorption of an enormous amount of fugacity of CO2 (fCO2) in the surface waters, even with a significant amount of inorganic carbon regenerated via CR. In 2010, there were even more riverine runoff nutrients into the ECS than in 2009. Surprisingly, the growth of phytoplankton in 2010 was not stimulated by enriched nutrients, and its growth was likely limited by low water temperature and/or low light intensity. Low temperature might also suppress planktonic metabolism, and this could explain why the CR was lower in 2010. During this period, lower surface water fCO2 might have mainly been driven by physical process(es). To conclude, these results indicate that organic carbon consumption (i.e. CR) in the ECS in spring might be controlled by the magnitude of planktonic activities and physical factor (e.g. temperature), and that the latter is especially important during a cold spring season. This further suggests that the high intraseasonal variability of organic carbon consumption needs to be kept in mind when budgeting the annual carbon balance.

scholarly journals Responses of Primary Productivity and Phytoplankton Community to the Atmospheric Nutrient Deposition in the East China Sea

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 210
Author(s):  
Qingwei Ma ◽  
Ying Chen ◽  
Fanghui Wang ◽  
Haowen Li
Keyword(s):  
Atmospheric Deposition ◽  
East China Sea ◽  
Phytoplankton Community ◽  
Marine Phytoplankton ◽  
Subsurface Water ◽  
East China ◽  
Surface Seawater ◽  
The East China Sea ◽  
Chl A ◽  
China Sea

Atmospheric deposition of nutrients to the surface seawater may significantly affect marine phytoplankton growth. Two in situ bioassay experiments were performed in the East China Sea (ECS) by adding nutrients (N, P, and Si) and atmospheric aerosols into the surface seawater. Chlorophyll a (Chl a) concentrations were largely enhanced by simultaneous input of N and P with the maximal increase of 0.68–0.78 μg Chl a per μmol N addition. This Chl a increment was significantly lower (0.19–0.47 μg) in aerosol treatments as a result of initial N-replete condition (N/P ratio ~50) and extremely high N/P ratio in aerosols (>300). Among the multiple influencing factors, atmospheric dry flux of NH4+ + NO3− (AN) was found to be an effective predictor for springtime Chl a in the ECS with a time lag of three days and were strongly correlated with Chl a concentrations on day 3 (r = 0.81, p < 0.001), which might be partly explained by the asynchronous supplies of N (atmospheric deposition) and P (subsurface water). Although dinoflagellates dominated the phytoplankton community in both initial seawaters, additions of P and N + P + Si profoundly enhanced the cell densities and dominance of diatom species Thalassiosira sp. and Nitzschia closterium in the 2012 and 2014 bioassay experiments, respectively. Moreover, the percentage of dinoflagellates were promoted by adding higher NH4+/NO3− ratio (6/4 vs. 1/9) when silicate was at a low concentration (~2 μmol L−1). Atmospheric deposition is likely to be an important N source supporting the high primary production in the ECS and its supply of excess N relative to P may influence dominant phytoplankton groups.

scholarly journals Biogeochemical characteristics of suspended particulates at deep chlorophyll maximum layers in the East China Sea

2017 ◽  
Author(s):  
Qianqian Liu ◽  
Selvaraj Kandasamy ◽  
Baozhi Lin ◽  
Huawei Wang ◽  
Chen-Tung Arthur Chen
Keyword(s):  
Organic Matter ◽  
East China Sea ◽  
East China ◽  
Deep Chlorophyll Maximum ◽  
The East China Sea ◽  
Chl A ◽  
Carbon And Nitrogen ◽  
China Sea ◽  
Marginal Seas ◽  
Suspended Particulates

Abstract. Continental shelves and marginal seas are key sites of particulate organic matter (POM) production, remineralization and sequestration, playing an important role in the global carbon cycle. Elemental and stable isotopic compositions of organic carbon and nitrogen are frequently used for characterizing organic matter and distinguishing their sources in suspended particulates and surface sediments in the marginal seas. Here we investigate suspended particulate matters (SPM) collected from the deep chlorophyll maximum (DCM) layer in the continental shelf of the East China Sea for particulate organic carbon and nitrogen (POC and PN) contents and their isotopic compositions (δ13CPOC and δ15NPN) to understand biogeochemical characteristics of POM straddling at biotic-dominated DCM depths. When combined with hydrographic parameters, such as temperature, salinity and turbidity, and chlorophyll a (Chl a), these elemental and isotopic results revealed that POM in the DCM layers was largely from the newly-produced, in situ phytoplankton-dominated OM and have wider δ13CPOC and δ15NPN compositions than previously thought. As supported by the POC to Chl a ratio, a large variation of δ13CPOC was resulted from the changes in primary productivity and phytoplankton species, whereas the nutrient status and δ15N of dissolved nitrate were the main controlling factors of δ15NPN variability in the DCM layers. Consistently, the spatial distribution of δ15NPN showed a similarity with the current pattern in the East China Sea, with 15N-enriched freshwater in the coastal region and Kuroshio Water in the northeast of Taiwan Island, but nutrient-depleted Taiwan Warm Current Water in the mid-shelf; as the latter seems to have promoted the N2-fixation, resulting in the depleted δ15NPN in the mid-shelf. Furthermore, SPM investigated here seems not to be influenced by the terrestrial organic matter supplied by the Yangtze River (Changjiang) in summer 2013, a finding that is contrary to a number of previous studies' conclusion. Nonetheless, given the complications associated with stable isotopes of organic matter, additional parameters such as radiocarbon and biomarkers are crucial to revalidate whether or not SPM in the DCM depths is influenced by terrestrial organic compounds in the river-dominated East China Sea.

scholarly journals Spatial variations in the Kuroshio nutrient transport from the East China Sea to south of Japan

2013 ◽  
Vol 10 (4) ◽  
pp. 6737-6762 ◽  
Author(s):  
X. Y. Guo ◽  
X.-H. Zhu ◽  
Y. Long ◽  
D. J. Huang
Keyword(s):  
East China Sea ◽  
East China ◽  
Nitrate Transport ◽  
The East China Sea ◽  
China Sea ◽  
Subsurface Maximum ◽  
Nitrate Flux ◽  
The Mean ◽  
South Of Japan ◽  
The Kuroshio

Abstract. Based on absolute geostrophic velocity calculated from repeated hydrographic data of 39 cruises from 2000 to 2009 and nitrate concentrations measured at the same sections from 1964 to 2011, we obtained temporally averaged nitrate flux (the product of velocity and nitrate concentration) and nitrate transport (integration of flux over a section) through 4 sections along the Kuroshio path from the East China Sea (sections PN and TK) to south of Japan (sections ASUKA and 137E). In addition, we examined section OK east of the Ryukyu Islands in order to understand the contribution of Ryukyu Current to the Kuroshio nutrient transport south of Japan. The mean nitrate flux shows a subsurface maximum core with a value of 10, 10, 11, 11, and 6 mol m–2 s–1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The depth of subsurface maximum core changes among five sections and is approximately 400, 500, 500, 400, and 800 m at sections PN, TK, ASUKA, 137E, and OK respectively. The mean downstream nitrate transport is 199.3, 176.3, 909.2, 1385.5, and 341.2 kmol m–1 at sections PN, TK, ASUKA, 137E, and OK respectively. The nutrient transports at these sections suggest the presence of Kuroshio nutrient stream from its upstream region to downstream. The deep current structure of Ryukyu Current (section OK) makes it contribute more nitrate transport than the Kuroshio in the East China Sea (section TK) to the Kuroshio south of Japan. In addition, the positive difference between the downstream nitrate transport through section ASUKA and the sum of nitrate transports through sections TK and OK, as well as the positive difference of downstream nitrate transport between sections 137E and ASUKA, suggest that the Kuroshio recirculation significantly intensifies the downstream (eastward) nitrate transport by the Kuroshio.

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