黄海微微型浮游植物对灰霾颗粒添加以及光照变化的响应

Response of Picophytoplankton to the Addition of Haze Particles and Change in Light Intensity in the Yellow Sea

本研究于2020年夏、秋两季,在黄海的三个站位开展了船基受控培养实验,研究了灰霾颗粒添加和光照变化(相较于海面约40%、68%和82%的光衰减)对微微型浮游植物生长、群落演替及碳生物量和叶绿素a(Chl a)比值的影响。结果表明,微微型浮游植物均表现出对总Chl a相当甚至主导的贡献能力,且所有培养站位初始海水中微微型浮游植物优势类群均为微微型真核浮游植物和聚球藻。在黄海中部和北部的贫营养海域,灰霾颗粒添加提供的氮能够促进微微型浮游植物的Chl a(Chl a_(pico))浓度、微微型真核浮游植物和聚球藻细胞丰度的增加,但光照变化的影响不显著。然而,微微型浮游植物碳生物量(C pico)和Chl a_(pico)比值(C pico/Chl a_(pico))随着灰霾颗粒的添加和光照强度的衰减呈降低趋势,这与浮游植物的光合色素合成水平密切相关。在近岸富营养海域,培养实验期间海面的光照强度较低,且由于海域水体浑浊,光照强度是影响微微型浮游植物生长和C pico/Chl a_(pico)比值的主要因素。Chl a_(pico)、细胞丰度和C pico/Chl a_(pico)比值均随着光照强度的衰减逐渐降低。本研究初步揭示了大气沉降和光照双因子调控下微微型浮游植物Chl a_(pico)和碳生物量的变化特征。

A series of on-board incubation experiments were conducted at three sampling stations in the Yellow Sea(YS)during Summer and Autumn of 2020,aiming to explore the effects of haze particle additions and changes in light intensity(about 40%,68%and 82%light attenuation compared with sea surface light intensity)on the growth,community succession and the ratio of carbon biomass to Chlorophyll a(Chl a)of picophytoplankton(0.2~2μm in cell size).The results showed that the picophytoplankton showed equal or even dominant contribution to the total Chl a,and the dominant groups of picophytoplankton in the initial seawater of all the culture sites were picoeukaryotes and synechococcus.In the middle and north of the Yellow Sea(corresponding to oligotrophic seawaters),the nitrogen supplied by haze particles promoted the increase in Chl a concentration of picophytoplankton(Chl a_(pico))and cell abundance of eukaryotic picophytoplankton and Synechococcus,but the effect of light intensity was not significant.The ratio of carbon biomass(C pico)and Chl a_(pico)(C pico/Chl a_(pico))decreased with the addition of haze particles and the attenuation of light intensity,which was closely related to the carbon metabolism pathway and the extent of photosynthetic pigment synthesis.On the other hand,the ratio of C pico/Chl a_(pico) was mainly regulated by light intensity in the nearshore eutrophic seawaters,which was characterized by relatively low light intensity and high turbidity of seawater.Chl a_(pico) concentration,cell abundance,and the ratio of C pico/Chl a_(pico) generally decreased with light attenuation.These results suggests that light intensity had a more obvious effect on the growth of picophytoplankton compared with the addition of haze particles in nearshore eutrophic seawaters.This study revealed the change pattern of Chl a_(pico) and carbon biomass of picophytoplankton under the effect of atmospheric deposition and light intensity.