春季长江口邻近外海网采浮游生物的生物量谱

Biomass size spectrum of net plankton in the adjacent area near the Yangtze River Estuary in spring

对2005年春季黄海南部、东海北部近江口外海水域网采的浮游生物个体大小的粒径分布进行研究,确定各粒级大小的功能群组成,建立此季该调查水域网采浮游生物的生物量谱。样品是用小、中、大型浮游生物网(网孔径为77、160、505μm)采集所得。三网具采集浮游生物个体大小粒径是连续的,其中浮游植物,其等效粒径(ESD)和含碳量范围分别为5~250μm、15pg^146ng;浮游动物,含碳量范围为115ng^7.5mg,ESD分别为120μm^5.8mm、200μm^2cm。所得网采浮游生物的标准生物量谱,总测区的斜率为-0.607±0.059、截距为19.45±0.46;各站位的生物量谱斜率为-0.889^-0.455、截距为12.866~16.863,两特征参数分布规律为南高北低,且具有显著的站位间差异。相关性分析表明截距和回归系数与粒级多样性有关。

Biomass size spectrum（BSS）is constructed by allocating all organisms into size classes according to their individual body mass（size）and computing the total biomass per size class.It proves to be an effective ataxonomic approach for analyzing the structure of the pelagic ecosystem.However,empirical data regarding planktonic size-structure in adjacent waters of Yangtze River Estuary are scarce.Based on the data from survey carried out in spring,2005,the individual size compositions and BSS of the net plankton were explored in the in adjacent waters of Yangtze River Estuary.Plankton samples were collected vertically from 31 stations with micro-,meso-and macro-plankton nets（77,160μm and 505μm mesh size）,respectively.Results revealed an approximately continuous size distribution of plankton individuals,from phytoplankton（5-250μm cell-1 in equivalent sphere diameter（ESD）,15pg-146ng C cell-1）to zooplankton（120μm-2cm ESD,115ng-7.5mg C ind-1）.The distribution of normalized biomass versus size（carbon scale）was linear on a double log plot at all stations.The normalized spectra slopes of the study area ranged from-0.889 to-0.445,and 12.866 to 16.863（all stations together,slope=-0.606,intercept=19.448）,indicating strong deviations from the ideal value（slope =-1.22）of a steady pelagic ecosystem.The slopes and intercepts varied significantly among the stations（p〈0.0001）and the higher values occurred in the southern part of study area.It concludes that the intercepts and correlation coefficients of net plankton spectra covaried roughly with size diversity and evenness in total plankton composition.