长江口大型底栖动物群落结构特征OACHSSCD

Based on investigations of macrobenthos at 24 stations in the Yangtze River Estuary during three distinct hydrological periods-August 2021(high-flow period),May 2022(normal-flow period),and February 2023(low-flow period),the study revealed:(1)A total of 194 taxa were identified,with Polychaeta(33.5％),Crustaceans(26.3％),and Mollusca(24.2％)constituting the dominant groups(84％combined).The dominant species across all hydrological periods was Heteromastus filiformis,though its dominance was generally low,indicating a relatively balanced community structure.(2)During the low,normal,and high-flow seasons,the mean densities were(138.04±48.84),(154.79±51.28),and(145.82±52.13)ind./m2,respectively;the mean wet weight biomasses were(6.727±1.729),(5.195±1.746),and(9.058±2.288)g/m2,respectively;the mean diversity indices(H')were(1.58±0.23),(1.63±0.32),and(1.76±0.34),respectively;the mean evenness indices(J')were(0.45±0.04),(0.50±0.05),and(0.63±0.03),respectively;and the mean richness indices(d)were 1.10±0.28,1.09±0.36,and 1.03±0.42,respectively.No significant differences(P＞0.05)were observed in mean density,biomass,or diversity index across the three periods.Abundance/Biomass Comparison(ABC)curves indicated that the macrobenthos communities were moderately disturbed during the low and normal-flow seasons,while the high-flow period exhibited structural stability.(3)Spatial cluster analysis revealed that the stations were divided into six groups,primarily attributed to regional environmental heterogeneity.Redundancy analysis(RDA)identified water temperature,salinity,pH,sediment organic carbon,grain size,and redox potential(Eh)as key driving factors.Sedimentary factors explained significantly more variance than water quality parameters during the low-flow period,while the opposite was true during the high-flow periods.(4)The study highlights that spatiotemporal differentiation of macrobenthos communities in the Yangtze Estuary was driven by dynamic coupling of water quality and sedimentary environmental factors,with dominant factors exhibiting period-specific characteristics across hydrological seasons.Targeted zonal management and seasonal monitoring strategies should be implemented to maintain the stability and biodiversity of the estuarine ecosystem.