Spatio-Temporal Variations of Winter Phytoplankton Blooms Northwest of the Luzon Island in the South China Sea

Abstract

Phytoplankton is a key component of marine ecosystems. Winter phytoplankton blooms are frequently observed northwest of Luzon Island in the South China Sea. In this study, with the multi-satellite merged ocean color remote sensing data from November 1999 to February 2015, we examine the spatial and temporal changes of chlorophyll-a (Chl-a) concentration and further investigate its response to physical environment parameters including wind speed, Ekman transport, Ekman pumping velocity, sea surface temperature, and sea level anomalies in the region northwest of Luzon Island. The main factors affecting the distribution of Chl-a are discussed by using the partial correlation analysis and multiple stepwise linear regression analysis. The results show that centers of winter Chl-a blooms northwest of Luzon Island often occur near 119.5°E, 19.5°N. The significant multiple correlation (r = 0.76, p < 0.01) between Chl-a and oceanic conditions indicates that both the wind component parallel to the coastline and the wind stress curls enhance the winter upwelling in the study area, consistent with previous studies. A novel finding in the present study is that the winter bloom center is located north of the upwelling center, attributed to the advection effect of the northward background coastal flow.

Spatiotemporal Expansion of Algal Blooms in Coastal China Seas

“…Summer and autumn are the primary seasons during which algal bloom outbreaks occur along the coast of China, with the peak occurring in the summer (Figure a–d). However, the highest intensity (>0.1 accumulated days/year) of algal blooms during winter occurs in the Luzon Strait (Figure d); this could be caused by coastal wind and the wind-driven upwelling in the Luzon Strait during winter. − Additionally, in the eastern Beibu Gulf, algal blooms exhibit the highest intensity (>1 accumulated days/year) and widest distribution (>3.2 × 10 4 km 2 ) of any other region during autumn (Figure c). Apart from the influence of terrestrial input, this region is greatly affected by nutrient transport through the Qiongzhou Strait, due to the intrusion of the west Guangdong coastal current. − …”

Mining and Analysis of the Traffic Information Situation in the South China Sea Based on Satellite AIS Data

“…In summary, analyzed from the perspective of seasonal influence, the whole number of ships in December is less than that in July, with a large difference of 1,942 ships in gate line 4. The difference in the number of ships is highly concentrated in small and medium-sized ships, mainly fishing boats and small surface boats near the coast and islands affected by the stronger northeast monsoon in winter (Gao et al, 2021). However, the number of ships in gate line 5 (Bashi Strait waters) is basically not affected by the season (mainly large ships voyage).…”

Research on three-dimensional monitoring system of algae concentration based on the unmanned ship

“…Chlorophyll-a is a vital component of phytoplankton, its concentration reflects the type and quantity of algae and the present number of phytoplankton [1][2][3][4] , making it one of the most important indicators of marine environment testing and an indispensable part of surveying the marine primary productivity [5][6] . In addition, chlorophyll-a is also associated with the occurrence of natural disasters such as blooms and red tides, which is an important parameter for evaluating the trophic state and the eutrophication of water bodies [7] .…”