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ABSTRACT
The wintertime variations and distributions of sea surface temperature (SST) and thermal fronts associated with the spatial distribution of ichthyoplankton were investigated in the continental shelf waters of the southern East China Sea (ECS) by using 10 year (2005–2015) satellite SST images with an entropy-based edge detection method. The Mainland China Coastal Front and Kuroshio Front (KF) in winter (December to March) were examined with SST gradient magnitudes (GMs) of 0.20–0.40 and 0.30–0.45°C Km−1, respectively, along the 50 m and 100–200 m isobaths in the southern ECS. These two fronts coincided with isotherms of 14–16°C and 21–22°C, respectively. The Mainland China Coastal Front pattern remained fairly stable along the 50 m isobaths, and the coexisting SST front and upwelling were shifted seaward or shoreward with the recession or intrusion of the KF during the winters. Notably, the SST GMs of the KF showed a significant strengthening that was higher than those of the past two decades. Moreover, the total abundance of the nearshore waters of the KF (which was occupied by approximately 75% neritic species) was 23 times higher than that of the offshore waters (which was occupied by approximately 63.60% oceanic species). We suggest that the generation of the KF in winter may act as the biological barrier of oceanic organisms and larval fishes in the study area.
Acknowledgements
The authors thank the crew of the Ocean Research II for providing information and assistance with the research experiment. We acknowledge Wallace Academic Editing for editing this manuscript. This research was supported by grants from the Ministry of Science and Technology (MOST 102-2611-M-019-020; 103-2611-M-019-009), Taiwan.
Disclosure statement
No potential conflict of interest was reported by the authors.