851 / 2024-09-19 16:26:58

Responses of zooplankton communities to currents and land-based pollution in the southwestern Taiwan Strait

Dongshan and Nan’ao Upwelling, Hanjiang River Plume,South China Sea Warm Current, Shantou Bay, Zhejiang-Fujian Coastal Current

 The ocean currents and river runoff in the East Asian monsoon region exhibit significant seasonal variations, posing a serious threat of eutrophication to numerous estuaries of the area due to land-based pollution. Seasonal patterns of zooplankton communities relating to the monsoon reversal have been documented in the area. However, there is limited understanding of the combined impacts of land-based pollution and monsoon reversal on marine zooplankton communities. The mechanisms driving zooplankton community dynamics were analyzed using data from Shantou Bay of the southwestern Taiwan Strait (TWS) in 2021. Zooplankton abundance and clusters correlate with water masses driven by seasonal variations of currents and runoff. The seasonal patterns of zooplankton dominant species and indicator species directly confirm the currents and runoff changing in seasons. The seasonal stability of the zooplankton diversity suggests the sea is the mixing zone for water masses with different nature all the year.  Eutrophication and malnutrition are two additional factors affecting zooplankton communities in the sea. Poor phytoplankton is a key limiting factor in spatial patterns of zooplankton communities during NEM. Eutrophication threats to the stability of the large zooplankton community. Basing on the relationships to water masses, currents, phytoplankton and nutrients, we suggest that variations of zooplankton communities with water masses are joint actions of currents and river runoff with abundant nutrients changing with the monsoon reversal in the southwestern TWS.