Page 110 - 《渔业研究》2025年第3期

第 3 期 王首吉等： 粤东海域表层海水叶绿素 a 时空分布特征 367

Temporal and spatial distribution characteristics of chlorophyll-a in surface
seawater of eastern Guangdong sea area

WANG Shouji ，PENG Yaoxiang ，PEI Pengbing ，CHEN Tingting ，
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CAI Dehua ，GUO Yan ，DU Hong 3*
(1. Guangdong Shantou Ecological and Environmental Monitoring Center, Shantou 515041, China;
2. Agro-Tech Extension Center of Guangdong Province, Guangzhou 510630, China;
3. Guangdong Provincial Key Laboratory of Marine Disaster Prediction and Prevention, College of Science,
Shantou University, Shantou 515063, China)
Abstract: [Objective] Current response measures for red tides in eastern Guangdong sea area remain limited to
manual tracking and monitoring, which suffer from significant spatial constraints and temporal delays. This
study aims to propose recommendations for the regular monitoring and early warning of red tides in eastern
Guangdong sea area. [Methods] Based on monitoring data from 9 cruises conducted in eastern Guangdong sea
area from 2021 to 2023, the distribution of chlorophyll-a concentration and its relationship with environmental
factors were analyzed. Multiple sources of information, including river inflows, regional ocean currents, and aqua-
culture distribution, were integrated to discuss phytoplankton distribution patterns in the region. [Results] 1) The
average chlorophyll-a concentration follows the pattern: estuary area>aquaculture area>offshore area; summer>
spring>autumn; Shantou City>Shanwei City>Chaozhou City>Jieyang City. 2) The dilution effect of river in-
flow reduced the likelihood of red tide outbreaks in estuary area. Regional ocean currents had a reverse impact
on the growth of offshore phytoplankton. Aquaculture area, subjected to dual pressures from river inflows and
ocean currents, combined with nutrient enrichment from fish and shellfish farming, were more prone to red tide
outbreaks. 3) Red tide outbreaks in Shantou City were attributed to multiple factors. The eutrophication in Zh-
elin Bay of Chaozhou City was severe but relatively stable, with no red tides reported in the past three years.
Phytoplankton growth in Jieyang City and Shanwei City relied more on nutrient inputs from offshore sources.
4) High chlorophyll-a concentration areas were mainly located in Zhelin Bay, the area from Nan’ao Island to
Shantou Port, the Lianjiang Estuary, and Jieshi Bay. [Conclusion] The four coastal cities in eastern Guang-
dong should establish a multi-center red tide monitoring and early warning system tailored to regional phyto-
plankton distribution. Shantou City should prioritize estuary and aquaculture areas, Chaozhou City should ad-
dress impacts of aquaculture types, Shanwei City should focus on internal dynamics of Jieshi Bay, and Jieyang
City should account for ocean current influences. The study provides reference materials for the normalized
monitoring of red tide in eastern Guangdong sea area.
Key words: eastern Guangdong sea area; chlorophyll-a; red tide outbreak; monitoring and early warning