Diel Variation in Phytoplankton Biomass Driven by Hydrological Factors at Three Coastal Monitoring Buoy Stations in the Taiwan Strait

Abstract

To investigate the diurnal variation in phytoplankton biomass and its regulating factors during the diurnal cycle, we conducted in situ observations in June 2018 at three buoy stations, including Douwei Buoy Station, Minjiang Estuary Buoy Station, and Huangqi Buoy Station on the western side of the Taiwan Strait. The calibration of buoy sensor data, including temperature, salinity, dissolved oxygen, pH, chlorophyll, and phycoerythrin, was conducted simultaneously. In addition, water sampling was conducted to measure chlorophyll a and phycoerythrin concentrations at hourly time intervals. The results showed that the 24 h cumulative chlorophyll a concentration order for the buoys was Minjiang Estuary (10.280 μg/L) > Huangqi (7.411 μg/L) > Douwei (4.124 μg/L). The Minjiang Estuary had a lower nighttime biomass proportion than Douwei and Huangqi. The diurnal variation in phytoplankton was jointly regulated by water masses, tides, and light. There were three response patterns, including the “light trumps tidal influences” pattern at Douwei, the “Low-tide, High-biomass” pattern at Minjiang Estuary, and the “High-tide, High-biomass” pattern at Huangqi. The prediction of algal blooms and hypoxia using buoy monitoring needs to be based on seasonal water mass background and tidal influence.

The Carbonate System of Penzhina Bay and the Shelikhov Gulf in the Sea of Okhotsk during Extreme Tides in Summer

“…High tidal energy is known to contribute to the resuspension of bottom sediments and the additional supply of nutrients from bottom sediments to the water column, which stimulates the rate of phytoplankton production [19]. On the other hand, the turbidity of water increases during such an event, which determines the light conditions in the water column and thus affects the state of phytoplankton and the direction of their production/destruction processes [50]. In estuaries with intensive tidal mixing, increased turbidity can lead to ecosystem phenomena such as hypoxia [51].…”