Abstract
Chlorophyll-a (Chl-a) concentration is a measure of phytoplankton biomass, and has been used to identify ‘red tide’ events. However, nearshore waters are optically complex, making the accurate determination of the chlorophyll-a concentration challenging. Therefore, in this study, a typical area affected by the Phaeocystis ‘red tide’ bloom, Qinzhou Bay, was selected as the study area. Based on the Gaofen-1 remote sensing satellite image and water quality monitoring data, the sensitive bands and band combinations of the nearshore Chl-a concentration of Qinzhou Bay were screened, and a Qinzhou Bay Chl-a retrieval model was constructed through stepwise regression analysis. The main conclusions of this work are as follows: (1) The Chl-a concentration retrieval regression model based on 1/B4 (near-infrared band (NIR)) has the best accuracy (R2 = 0.67, root-mean-square-error = 0.70 μg/L, and mean absolute percentage error = 0.23) for the remote sensing of Chl-a concentration in Qinzhou Bay. (2) The spatiotemporal distribution of Chl-a in Qinzhou Bay is varied, with lower concentrations (0.50 μg/L) observed near the shore and higher concentrations (6.70 μg/L) observed offshore, with a gradual decreasing trend over time (−0.8).
Highlights
Qinzhou Bay is located in southern Guangxi, China, and is part of Beibu Bay, covering an area of 908.37 km2 between latitudes and longitudes of 21◦ 330 2000 –21◦ 540 3000 N and 108◦ 280 2000 –108◦ 450 3000 E, respectively
The bay consists of inner (Maowei Sea) and outer (Qinzhou Bay) bays, and is generally ‘gourd-shaped’ [35]
Bay to explore the spatiotemporal variations in the a Chl-a concentration model for Qinzhou Bay to explore the spatiotemporal variations in of Qinzhou
Summary
Academic Editor: Carlos Antonio Da Silva Junior. Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Coastal waters are an important ecosystem that humans depend on. They play an important role in fisheries, industry, and tourism [1,2]. With the rapid development of coastal economies, the pressures on the natural environment along the coast from urban expansion, population growth, and industrialization are increasing. Many environmental problems caused by unreasonable planning, unscientific management, and uncoordinated production have emerged [3]
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