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Locations of sampling sites off eastern Taiwan and the inserted map showing the full path of typhoon Saola in the northwest Pacific Ocean.
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In this study, two cruises were conducted across the mainstream of the Kuroshio off eastern Taiwan before and after the passage of Typhoon Saola in summer 2012. The continuous underway pCO2 (i.e., partial pressure of CO2) measurements revealed that surface seawater pCO2 (SS pCO2) displayed spatial variations in response to typhoon passage. The simu...
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The climatology of different classifications (based on the intensity at the landfall time) of tropical cyclones (TCs) making landfall in Guangdong Province of China during 1951–2020 (70 years) is investigated using the best track data from the China Meteorological Administration and ERA5 reanalysis data. There were 234 TCs making landfall in Guangd...
Citations
... Temperature and salinity were continually recorded by a conductivity/temperature/depth recorder (CTD) (SBE9/11 plus) (Sea-Bird Electronics, Bellevue, WA, USA). The current velocity was measured by a 150 kHz shipboard acoustic Doppler current profiler (ADCP; Teledyne RD Instruments, Poway, CA, USA) [41]. To determine the concentrations of chlorophyll a (Chl a) and inorganic nutrients and the abundance of picophytoplankton, water samples were collected using 20-L GO-Flo bottles (General Oceanics, Miami, FL, USA) mounted on the CTD rosette sampler at six depths from 5 m to 300 m. ...
Simple Summary
The cell enumeration, 16S rRNA phylogenetic analysis, and hydrography determination were conducted to reveal the ecology of prokaryotic picoplankton in the subtropical Kuroshio current. The picocyanobacteria (i.e., Synechococcus and Prochlorococcus), contributing more than 50% of chlorophyll a, were important primary producers in the subtropical Kuroshio current. The notable seasonal distributions of picocyanobacteria and hydrography were also well described. We suggested the ambient nutrient contents should be the crucial parameter to determine the seasonal patterns of Synechococccus and Prochlorococcus in the study area. Because of the ability to compete for nutrients in an oligotrophic environment, picocyanobacteria would become dominant primary producers in marine ecosystems under the scenario of global warming.
Abstract
The nutrient-scarce, warm, and high-salinity Kuroshio current has a profound impact on both the marine ecology of the northwestern Pacific Ocean and the global climate. This study aims to reveal the seasonal dynamics of picoplankton in the subtropical Kuroshio current. Our results showed that one of the picocyanobacteria, Synechococcus, mainly distributed in the surface water layer regardless of seasonal changes, and the cell abundance ranged from 10⁴ to 10⁵ cells mL⁻¹. In contrast, the maximum concentration of the other picocyanobacteria, Prochlorococcus, was maintained at more than 10⁵ cells mL⁻¹ throughout the year. In the summer and the autumn, Prochlorococcus were mainly concentrated at the water layer near the bottom of the euphotic zone. They were evenly distributed in the euphotic zone in the spring and winter. The stirring effect caused by the monsoon determined their distribution in the water column. In addition, the results of 16S rRNA gene diversity analysis showed that the seasonal changes in the relative abundance of Synechococcus and Prochlorococcus in the surface water of each station accounted for 20 to 40% of the total reads. The clade II of Synechococcus and the High-light II of Prochlorococcus were the dominant strains in the waters all year round. Regarding other picoplankton, Proteobacteria and Actinobacteria occupied 45% and 10% of the total picoplankton in the four seasons. These data should be helpful for elucidating the impacts of global climate changes on marine ecology and biogeochemical cycles in the Western Boundary Currents in the future.
... Fan et al. [8] conducted two cruises across the mainstream of the Kuroshio off eastern Taiwan before and after the passage of Typhoon Saola in summer 2012. The continuous underway pCO2 (partial pressure of CO2) measurements revealed that surface seawater pCO2 (SS pCO2) displayed spatial variations in response to typhoon passage. ...
The marine environment includes the waters of seas and estuaries, the seabed and its subsoils, and all marine wildlife and its sea and coastal habitats [...]
The Luzon Strait (LS) is a key region for estimating carbon sources and sinks in the South China Sea (SCS) and is highly influenced by the Kuroshio Current (KC) and typhoons. Understanding the variations in the sea surface partial pressure of carbon dioxide (pCO2-sw) under the combined effects of typhoons and KC in this region is crucial for estimating local and regional changes in ocean carbon flux. Based on valuable in situ pCO2-sw and remote sensing data, this study aimed to reveal the temporal variations and the physical mechanisms of pCO2-sw variations under the comprehensive effects of both typhoons and Kuroshio Intrusion (KI) in the LS. One week after the passage of the tropical cyclone (TC) Nanmadol, the concentration in the pCO2-sw and the influencing mechanisms varied in three different regions (W1–W3) on Transect A (120°E). In the region dominated by SCS waters (W1), the average pCO2-sw increased by 5.1 μatm after TC, which was mainly due to the TC “Wind Pump” inducing strong vertical mixing, which brought dissolved inorganic carbon (DIC)-rich deeper water up to the surface. In the region affected by KC (W2 and W3), pCO2-sw decreased after the TC (−8.2 μatm and −1.8 μatm, respectively) with TC-enhanced KI because the invasion of lower pCO2-sw of Kuroshio waters inhibited the TC-induced upwelling. More significant TC-induced upwelling (W3) would alleviate the decrease in pCO2-sw caused by the TC-enhanced KI. This study is a rare case providing a better understanding of the variations in pCO2-sw under TC-enhanced KI, which provides support for regional climate change prediction and carbon flux estimation in the western boundary current regions.
New data were obtained on the formation mechanisms of relief sediment waves (SWs) in Peter the Great Bay of the Sea of Japan. From the studies, we can assume that the sediment waves in the bay originate from two types of turbidity (TB) currents: (1) fine-dispersed TB currents caused by disintegrating internal waves and entrained by the Primorsky current along the shelf through SWs troughs; (2) fine- and coarse-grained TB currents, formed and entrained by the Primorsky current, intensified by the typhoons. This work presents the geological structure of the shelf area containing SWs. We established that the area of SWs location is on the border of change in facies conditions of sediment bedding in the bay. The transition from the inner shelf facies to the outer shelf facies occurs at a depth of 50–60 m. We analyzed the space variability of temperature and sound speed fields peculiar to the region on the results of hydrological CTD measurements and long-term measurements with moored vertical thermostrings. In the course of measurements, seven typhoons during their passage off the Primorye coast of the Russian Federation were registered. We found a significant change in the hydrological situation in the bay under the influence of extreme external factors. Under calm meteorological conditions, up to three mild thermoclines were observed in the bay, located at depths of 8–15 m, 30–35 m, and 45–60 m. During the passage of typhoons, they combined into one powerful thermocline at a depth of approximately 50–60 m, and in some cases, a high-gradient thermocline formed at the depths of 30–40 m (about 12–15 °C per 10 m of depth). The high-gradient layer significantly increases the amplitude and strength of internal gravity waves, thereby increasing the speed of currents in the water media. We should note that this period of transformation of the hydrological profile on the shelf under the influence of typhoons covers the period from August to October-November. We established that in the SWs location area, firstly, the process of internal waves disintegration intensifies in the autumn season, resulting in the formation of the waves with lengths close to the SWs horizontal scales (SWs wavelengths); secondly, under the influence of the typhoons entering the Sea of Japan, the kinetic energy of the shelf branch of the Primorsky current increases. In this case, it acts as a source of TB currents, including medium- and coarse-grained sedimentary material that forms SWs.
