Seasonal Compositions of Size-Fractionated Surface Phytoplankton Communities in the Yellow Sea

Abstract

Little information on the phytoplankton community in the Yellow Sea (YS)—especially size-fractionated phytoplankton—is currently available, in comparison to the various physicochemical studies in the literature. Using high-performance liquid chromatography (HPLC), size-fractionated phytoplankton communities were seasonally investigated in the YS in 2019. In the study period, diatoms (55.0 ± 10.2%) and cryptophytes (16.9 ± 9.3%) were the dominant groups. Due to the recent alteration in inorganic nutrient conditions reported in the YS, the contribution of diatoms was lower than in previous studies. The large-sized phytoplankton group (>20 µm) was dominated mostly by diatoms (89.0 ± 10.6%), while the small-sized phytoplankton group (<20 µm) was also dominated by diatoms (41.9 ± 9.1%), followed by cryptophytes (19.2 ± 9.8%). The contributions of small-sized diatoms (<20 µm) have been overlooked in the past, as they are difficult to detect, but this study confirms significant amounts of small-sized diatoms, accounting for 62.3% of the total diatoms in the YS. This study provides an important background for assessing the seasonal variations in different-sized diatom groups in the YS. Further detailed studies on their potential ecological roles should be conducted, in order to better understand marine ecosystems under future warming scenarios.

First Estimation of the Annual Biosynthetic Calorie Production by Phytoplankton in the Yellow Sea, South Sea of Korea, East China Sea, and East Sea

“…Specifically, the seasonal patterns of integrated chlorophyll a concentration in the YS, SS, and ES were consistent with the typical bimodal seasonal cycle observed in phytoplankton biomass within temperate regions, as previously reported [37,[46][47][48][49][50]. Typically, these regions exhibit higher chlorophyll a concentration during the spring bloom, followed by a decline in the nutrient-depleted summer with strong stratification, and a subsequent second bloom in the fall [37,[46][47][48][49][50]. In our observation period, the concentrations of major inorganic nutrients exhibited significant variability during winter but remained relatively low in summer [37].…”

“…The integrated chlorophyll a concentration displayed distinct seasonal variations across the observed periods, as shown in Figure 2. Specifically, the seasonal patterns of integrated chlorophyll a concentration in the YS, SS, and ES were consistent with the typical bimodal seasonal cycle observed in phytoplankton biomass within temperate regions, as previously reported [37,[46][47][48][49][50]. Typically, these regions exhibit higher chlorophyll a concentration during the spring bloom, followed by a decline in the nutrient-depleted summer with strong stratification, and a subsequent second bloom in the fall [37,[46][47][48][49][50].…”

Integrated Ecosystem Assessments for Fisheries Management in the Yellow Sea, the East China Sea, and the East/Japan Sea

“…This change in the dominant phytoplankton community structure is likely due to the recent low-nutrient conditions after the construction of the Three Gorges Dam in Changjiang River. Kim et al (2022b) [4] identify size-fractionated phytoplankton communities seasonally in the Yellow Sea based on the HPLC results. This study provides important information on the contribution of seasonal variations in small-sized diatom to the phytoplankton community in the Yellow Sea, which has been overlooked to date.…”