scholarly journals Phytoplankton growth and consumption by microzooplankton stimulated by turbulent nitrate flux suggest rapid trophic transfer in the oligotrophic Kuroshio

2020 ◽  
Vol 17 (9) ◽  
pp. 2441-2452 ◽  
Author(s):  
Toru Kobari ◽  
Taiga Honma ◽  
Daisuke Hasegawa ◽  
Naoki Yoshie ◽  
Eisuke Tsutsumi ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
Phytoplankton Growth ◽  
Life Stages ◽  
Biological Productivity ◽  
Dilution Experiments ◽  
Nitrate Flux ◽  
Enrichment Experiments ◽  
The Kuroshio

Abstract. The Kuroshio Current has been thought to be biologically unproductive because of its oligotrophic conditions and low plankton standing stocks. Even though vulnerable life stages of major foraging fishes risk being entrapped by frontal eddies and meanders and encountering low food availability, they have life cycle strategies that include growing and recruiting around the Kuroshio Current. Here we report that phytoplankton growth and consumption by microzooplankton are stimulated by turbulent nitrate flux amplified by the Kuroshio Current. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Graduated nutrient enrichment experiments show that growth rates of phytoplankton and microheterotroph communities were stimulated within the range of the turbulent nitrate flux. Results of dilution experiments imply significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance biological productivity in the Kuroshio.

scholarly journals Phytoplankton productivity and rapid trophic transfer to microzooplankton stimulated by turbulent nitrate flux in oligotrophic Kuroshio Current

2019 ◽  
Author(s):  
Toru Kobari ◽  
Taiga Honma ◽  
Daisuke Hasegawa ◽  
Naoki Yoshie ◽  
Eisuke Tsutumi ◽  
...  
Keyword(s):  
Turbulent Mixing ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
Biological Productivity ◽  
Phytoplankton Productivity ◽  
Kuroshio Front ◽  
Dilution Experiments ◽  
Nitrate Flux ◽  
Enrichment Experiments ◽  
The Kuroshio

Abstract. The Kuroshio Current has been thought to be biologically unproductive due to oligotrophic conditions and low plankton standing stocks. Nevertheless, major foraging fishes are known to grow and recruit around the Kuroshio Current. While mixing and advection supplying nutrients to the euphotic zone are happened by eddies and meanders but limited at the Kuroshio front, there is a risk that survival of vulnerable life stages is encountered under the low food availability. Here we report that phytoplankton productivity is stimulated by turbulent nitrate flux amplified with the Kuroshio Current and rapidly transferred to microzooplankton through their grazing. Oceanographic observations demonstrate that the Kuroshio Current topographically enhances significant turbulent mixing and nitrate influx to the euphotic zone. Gradual nutrient enrichment experiments show growth rates of phytoplankton and microzooplankton communities stimulated within a range of the turbulent nitrate flux. Dilution experiments imply a significant microzooplankton grazing on phytoplankton. We propose that these rapid and systematic trophodynamics enhance invisible biological productivity in the Kuroshio.

Chemical speciation of iron in the euphotic zone along the Kuroshio Current

2021 ◽  
Vol 233 ◽  
pp. 103966
Author(s):  
Mitsuhide Sato ◽  
Jun Nishioka ◽  
Kazuyuki Maki ◽  
Shigenobu Takeda
Keyword(s):  
Chemical Speciation ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
The Kuroshio

scholarly journals Phytoplankton and Bacterial Responses to Monsoon-Driven Water Masses Mixing in the Kuroshio Off the East Coast of Taiwan

2021 ◽  
Vol 8 ◽  
Author(s):  
Chao-Chen Lai ◽  
Chau-Ron Wu ◽  
Chia-Ying Chuang ◽  
Jen-Hua Tai ◽  
Kuo-Yuan Lee ◽  
...  
Keyword(s):  
East Coast ◽  
Three Dimensional ◽  
Euphotic Zone ◽  
Kuroshio Current ◽  
Southwest Monsoon ◽  
Three Dimensional Model ◽  
Southern Taiwan ◽  
First Time ◽  
The Kuroshio ◽  
Mixing Water

Biogeochemical responses to mixing were examined in two cruise surveys along a transect across the Kuroshio Current (KC) in May and July 2020. Two stations located at the South China Sea (SCS)–KC mixing and the KC waters were chosen for the diel study. In the euphotic zone (~100 m depth), the average values of nitrate (0.97–1.62 μM), chlorophyll-a (Chl-a, 0.36–0.40 mg/m3), and primary production (PP; 3.46 ± 1.37 mgC/m3/day) of the mixing water station (MWS) of the two cruises were several folds higher than those of the KC station (KCS; nitrate, 0.03–0.10 μM; Chl-a, 0.14–0.24 mg/m3; and PP, 0.91 ± 0.47 mgC/m3/day). In the July cruise, the maximal bacterial production (BP) at the MWS (3.31 mgC/m3/day) was 82% higher in comparison with that of the KCS (1.82 mgC/m3/day); and the readings of Chl-a showed no trend with BP in the oligotrophic KCS, but a positive relationship was found among these measurements at the mesotrophic MWS. This implies that the trophic status of the system might affect phytoplankton–bacteria interactions. The backward-trajectory analyses conducted by an observation-validated three-dimensional model identified that the prevailing southwest monsoon drove a northeastward “intrusion” of the SCS waters in July 2020, resulted in mixing between SCS and Kuroshio (KC) waters off the east coast of southern Taiwan. For the first time, this study demonstrates that the high biological biomass and activities that occur in the KC are induced by the northward intrusion of the SCS waters.

Growth pattern of the siliceous skeletons of living Spumellaria (Radiolaria) from the Kuroshio Current, offshore southwestern Shikoku Island, Japan

2021 ◽  
pp. 100504
Author(s):  
Rie S. Hori ◽  
Takenobu Shinki ◽  
Akihiro Iwakiri ◽  
Atsushi Matsuoka ◽  
Noritoshi Suzuki ◽  
...  
Keyword(s):  
Growth Pattern ◽  
Kuroshio Current ◽  
The Kuroshio

scholarly journals Review of the Japanese records of an endangered grouper, Epinephelus tukula, with comments on its population status (Teleostei, Serranidae)

ZooKeys ◽  
2018 ◽  
Vol 772 ◽  
pp. 153-163 ◽  
Author(s):  
Atsunobu Murase ◽  
Ryohei Miki ◽  
Masaaki Wada ◽  
Masahide Itou ◽  
Hiroyuki Motomura ◽  
...  
Keyword(s):  
Distribution Pattern ◽  
Continuous Distribution ◽  
Kuroshio Current ◽  
Red List ◽  
The Internet ◽  
Ryukyu Islands ◽  
Population Status ◽  
Warm Current ◽  
Japanese Waters ◽  
The Kuroshio

The Potato Grouper, Epinephelustukula, is relatively rare worldwide. Records from the northernmost part of its range (Japan) have been few, resulting in a “Critically Endangered” listing on the Red List for Japan. The Japanese records were revised by examining literature, new specimens, photographs, and the internet, and a continuous distribution pattern from the tropical Ryukyu Islands (including adult individuals) to temperate regions affected by the Kuroshio Current were delineated; this suggests the species inhabits tropical Japan and can spread to temperate regions via the warm current. The species possibly reproduces in Japanese waters but further reproductive ecology research is required.

Sedimentary mercury and antimony revealed orbital-scale dynamics of the Kuroshio Current

2021 ◽  
Vol 265 ◽  
pp. 107051
Author(s):  
Jianjun Zou ◽  
Yuan-Pin Chang ◽  
Aimei Zhu ◽  
Min-Te Chen ◽  
Selvaraj Kandasamy ◽  
...  
Keyword(s):  
Kuroshio Current ◽  
The Kuroshio

scholarly journals Impacts of the Kuroshio Intrusion through the Luzon Strait on the Local Precipitation Anomaly

2021 ◽  
Vol 13 (6) ◽  
pp. 1113
Author(s):  
Wen-Pin Fang ◽  
Ding-Rong Wu ◽  
Zhe-Wen Zheng ◽  
Ganesh Gopalakrishnan ◽  
Chung-Ru Ho ◽  
...  
Keyword(s):  
Kuroshio Current ◽  
Precipitation Anomaly ◽  
Luzon Strait ◽  
Sea Surface ◽  
Research Quality ◽  
Northwestern Pacific ◽  
Kuroshio Intrusion ◽  
Vertical Advection ◽  
Budget Analysis ◽  
The Kuroshio

The Kuroshio Current has its origin in the northwestern Pacific, flowing northward to the east of Taiwan and the northern part of Luzon Island. As the Kuroshio Current flows northward, it quasi-periodically intrudes (hereafter referred to as Kuroshio intrusion (KI)) into the northern South China Sea (SCS) basin through the Luzon Strait. Despite the complex generation mechanisms of KI, the purpose of this study is to improve our understanding of the effects of KI through the Luzon Strait on the regional atmospheric and weather variations. Long-term multiple satellite observations, including absolute dynamic topography, absolute geostrophic currents, sea surface winds by ASCAT, multi-scale ultra-high resolution sea surface temperature (MURSST) level-four analysis, and research-quality three-hourly TRMM multi-satellite precipitation analysis (TMPA), was used to systematically examine the aforementioned scientific problem. Analysis indicates that the KI is interlinked with the consequential anomalous precipitation off southwestern Taiwan. This anomalous precipitation would lead to ~560 million tons of freshwater influx during each KI event. Subsequently, independent moisture budget analysis suggests that moisture, mainly from vertical advection, is the possible source of the precipitation anomaly. Additionally, a bulk formula analysis was applied to understand how KI can trigger the precipitation anomaly through vertical advection of moisture without causing an evident change in the low-level flows. These new research findings might reconcile the divisiveness on why winds are not showing a synchronous response during the KI and consequential anomalous precipitation events.

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