Nutrient distribution and effects on phytoplankton assemblages in the western Korea/Tsushima Strait

Abstract

In this study, we investigated the relationship between seasonal/annual variation in water masses and nutrients, and the effects of nutrients on phytoplankton assemblages in the western Korea/ Tsushima Strait. We collected water samples at least once per month from March 2006 to January 2008. There was seasonal variation in nutrient concentrations, with higher values in winter than in summer, and there was annual variation in chlorophyll-a concentration and phytoplankton abundance during spring, with values being approximately three and 10 times higher, respectively, in 2007 than in 2006. Phytoplankton abundance was also approximately four times higher in 2007 than in 2006 during the stratification periods. Our findings suggest that when the supply of nutrients to the upper layer is increased as a result of the Tsushima Warm Water Current and the effect of typhoons, they regulate the abundance and composition of phytoplankton assemblages in the Korea/Tsushima Strait, inducing a succession from flagellates to diatoms.

Water Mass Control on Phytoplankton Spatiotemporal Variations in the Northeastern East China Sea and the Western Tsushima Strait Revealed by Lipid Biomarkers

“…Our study shows the order of brassicasterol > dinosterol > C 37 alkenones (concentrations; both maximum and mean values) and B/∑PB (45%–96%) > D/∑PB (4.3%–50%) > A/∑PB (0–20.77%) in the NEECS‐WTS in summer and autumn. The relatively high values of B/∑PB suggest the dominance of diatoms, consistent with the results in the NEECS‐WTS and adjacent areas in previous studies using small subunit ribosomal RNA pyrosequencing (Boopathi et al, ) and microscopic counting (Guo et al, ; Jang et al, ). For example, Guo et al () studied phytoplankton assemblages in the PN section of the ECS in summer by the Utermöhl method, showing that Bacteriastrum comosum and Chaetoceros decipiens were the dominant diatom species in offshore areas influenced by the Kuroshio intrusion.…”

Macroscale‐wide nutrient inversions in the subsurface layer of the Japan Sea during summer

“…The mixture of these three types of water could also disturb the lack of a relationship between salinity and nutrient concentration at the salinity maximum. Phytoplankton nutrient consumption can also explain why the mean nutrient concentration of the subsurface maximum (Figure ) is lower than that of the Tsushima Strait bottom water [ Jang et al ., ; Morimoto et al ., ].…”

Remote impacts of 2009 and 2015 El Niño on oceanic and biological processes in a marginal sea of the Northwestern Pacific

“…Although the relationship between the local oceanic processes and climatic factors has been highlighted, the response of coastal hydrodynamics and marine ecosystems to El Niño is not completely understood 8 – 10 . For example, the coastal hydrodynamic models included complex interactions between Pacific basin-scale wind forcing and local wind stress in order to predict the seasonal cycle of volume transport, but did not include interannual climate variabilities 11 .…”

“…Ref. 10 suggested that the typhoon-dependent nutrient supply largely regulates the abundance and composition of the phytoplankton assemblages. These studies were generally based on short-term (< 2 years) observations rather than long-term monitoring efforts 10 .…”

“… 10 suggested that the typhoon-dependent nutrient supply largely regulates the abundance and composition of the phytoplankton assemblages. These studies were generally based on short-term (< 2 years) observations rather than long-term monitoring efforts 10 . Therefore, volume transport and zooplankton abundance potentially depend on the poorly understood interplay between oceanic processes and climate systems, and require an in-depth understanding of the impact of El Niño on the local weather and marine ecosystems.…”