山东近海分粒级叶绿素a的时空格局及其成因分析OA北大核心CSCDCSTPCD

Phytoplankton are fundamental components of marine ecosystems,with variations in particle size influ-encing their photosynthetic efficiency and productivity,nutrient utilization strategies,biogeochemical cycles,and responses to climate change.Herein,we performed a systematic investigation of the spatiotemporal patterns of size-fractionated chlorophyll a and their underlying causes in the coastal waters of Shandong.The results provided critical insights into the structural and functional dynamics of this regional ecosystem.Based on three marine sur-veys conducted between 2022 and 2023,the spatiotemporal distribution and size composition of chlorophyll a in Shandong's coastal waters were delineated,and their relationships with physicochemical factors and shellfish-algae aquaculture were analyzed.Results indicated that chlorophyll a concentrations peaked during summer(average 2.94±3.23 μg/L),exhibiting a general nearshore-high and offshore-low distribution pattern.Furthermore,elevated levels were observed in Laizhou Bay,Rongcheng-Rushan,and Qingdao-Rizhao coastal areas,where abundant ni-trogen supported high phytoplankton biomass.Moreover,substantial seasonal variations in phytoplankton size composition were identified,where micro-and picophytoplankton dominated in spring;nano-and picophytoplank-ton prevailed in summer,and during winter,the largest proportion comprised microphytoplankton,followed by nanophytoplankton.Beyond the influence of temperature,turbidity,and nutrients on the phytoplankton size struc-ture and spatiotemporal patterns,selective feeding by filter-feeding bivalves and competition with kelp cultivation were identified as modifying factors of the phytoplankton size spectrum.These findings provide valuable data and scientific references for future ecosystem studies and better ecological conservation in Shandong's coastal waters.