胶州湾鱼类群落优势种组成的时空变化

优势种对群落结构有明显的控制作用,但优势度作为一个综合指标在不同时空尺度下的变异性常常被忽略。根据2008―2012年在胶州湾进行的渔业资源调查数据,以相对重要性指数(index of relative importance,IRI)表征鱼类种类优势度,应用bootstrap和多元线性回归模型(the multiple linear regression model)等方法分析了该海域的优势种组成及其在年份、季节、海区间的变化。结果表明,优势种有明显更替,六丝钝尾虾虎鱼(Chaeturichthys hexanema)和方氏云鳚(Pholis fangi)等小型底层鱼类更替为主要优势种,2008―2012年间分别占总渔获量的9.79%和10.71%,优势度分别为3285和2068;优势种存在明显季节变化,春季为方氏云鳚,夏季为细条天竺鲷(Apogonichthys lineatus),秋季和冬季是六丝钝尾虾虎鱼;空间上,湾口和湾内优势种组成相似,与湾外差异较大。多元线性回归分析表明,主要优势种中方氏云鳚优势度逐年升高,而六丝钝尾虾虎鱼相对下降,年际差异极显著(P0.01),呈现明显的群落演替过程。优势度主要受洄游产卵、水温、底质类型、水深以及饵料生物等因素的综合影响。

Temporo-spatial heterogeneity of dominant fish species in the Jiaozhou Bay community

Although dominant species exert the most control on community structure,the temporo-spatial heterogeneity of dominance as an integrative indicator has been often overlooked.To study fish community structure in Jiaozhou Bay,we analyzed 2008-2012 survey data from this area to determine species dominance (with IRI,index of relative importance) and variation in dominant species (with bootstrapping and multivariate linear regression).The results indicate that dominant species have changed substantially compared with previous studies.Chaeturichthys hexanema and Pholisfangi were the most dominant,comprising 9.79％ and 10.71％ of the total catch,with dominance indices of 3285 and 2068,respectively.Species dominance changed significantly between seasons,with P.fangi dominant in the spring,Apogonichthys lineatus in the summer,and C.hexanema in the fall and winter.Species composition differences were minor between the mouth and inner bay but notable in the outer bay.Multivariate linear regressions showed that during the survey period,P.fangi gradually increased in dominance whereas C.hexanema decreased.This difference was significant across years (P ＜ 0.01),implying obvious succession.Our analysis suggested that dominance heterogeneity between species may be driven by migration habits,seasonal fluctuations in water temperature,sediment type/depth,and the availability of forage organisms.