Seasonal variation in the phytoplankton community of a continental-shelf sea: the East China Sea

Abstract

To better understand seasonal variation in phytoplankton community structure in the East China Sea (ECS), 4 research cruises were carried out between August 2009 and June 2011 over the continental shelf. Phytoplankton community structure and ambient seawater physicochemical parameters were examined. The phytoplankton community in the ECS was mainly composed of diatoms and dinoflagellates, with 242 taxa in 70 genera of diatoms and 104 taxa in 26 genera of dinoflagellates. Several species of Chlorophyta, Chrysophyta, and Cyanophyta were also observed. Chain-forming diatoms were the most dominant phytoplankton group throughout the year, except in spring when dinoflagellates dominated in coastal waters. Monsoon-induced turbulence played a significant role in regulating the dominance of dinoflagellates among seasons, with calm water favoring the growth of dinoflagellates and turbulent water inhibiting them. Phytoplankton abundance was always higher in coastal than offshore waters, mainly determined by nutrient availability. A Prorocentrum dentatum bloom and a Chaetoceros debilis bloom were observed in the Yangtze River estuary in spring 2011 and fall 2010, respectively. The blooms differed greatly in community diversity and cell abundance distribution, potentially affecting organic carbon export. In general, 3 different hydrographic water systems (coastal water, shelf mixed water, and Kuroshio water) were identified from a temperature−salinity plot of the ECS, and phytoplankton abundance showed spatially and temporally different distribution patterns in these 3 water systems. The nutrient N:P ratio, but not the Si:N ratio, played a significant role in regulating the phytoplankton community structure and the formation of the spring coastal dinoflagellate bloom in the ECS.

In Situ and Satellite Observations of Phytoplankton Size Classes in the Entire Continental Shelf Sea, China

“…Some previous studies have suggested that nutrients have positive correlations with larger phytoplankton and negative correlations with smaller phytoplankton in the YS and the ECS (Deng et al, ; Sun et al, ). Indeed, higher dissolved inorganic nitrogen, phosphate, and silicate along coastlines and in the Changjiang Estuary and its adjacent areas were observed (Gong et al, ; Guo et al, ; Liu et al, ; Wang et al, ; Zhang et al, ), supporting our results that micro and nanoplankton were distributed with higher percentages in nearshore areas (Figure ). With the enhanced solar radiation in April, sea surface temperature increased and the stratification occurred in the central YS (Li et al, ; Yu et al, ), preventing the supplementary of nutrients in the surface.…”

Dissolved silicon isotopic compositions in the East China Sea: Water mass mixing vs. biological fractionation

“…PP in winter is approximately one order of magnitude lower than the 200-1000 mg C m 22 d 21 reached in summer, primarily due to poor growth conditions such as reduced light availability (Gong et al 2003;Chiang et al 2004;Liu et al 2010). As a result of the overall eutrophic condition on the East China Sea shelf, the phytoplankton abundance is frequently dominated by diatoms, which, however, show large spatial and seasonal variations (Furuya et al 1996;Chiang et al 1999;Furuya et al 2003;Chiang et al 2004;Guo et al 2014). In later spring/summer, the highest abundances of diatoms (exceeding 10 5 cells L…”

Impact of Hydrological Conditions on the Biogeochemical Dynamics of Suspended Particulate Organic Matter in the Upper Mixed Layer of the Southern East China Sea

“…This idea is supported by the various phytoplankton groups in the southern ECS that are abundant in large‐sized diatoms and dinoflagellates and small‐sized cyanobacteria (Jiao et al, ; Liu, Xiao, et al, ). The species‐related changes in ε f and a are also likely responsible for the similar relationship between autumn and summer data (Figure a) because of the dominance of same phytoplankton community: diatoms and dinoflagellates (Guo et al, ). Moreover, the constant primary productivity effect on δ 13 C of ~0.02‰ per μg/L POC is also observed in Prydz Bay (Kopczyńska et al, ; Zhang et al, ) and Ross Sea (Villinski et al, ) in Antarctica (Figure b), where the phytoplankton community is dominated by diatoms.…”