【作者】 林小苹；

【导师】 黄长江；

【作者基本信息】 汕头大学 ， 海洋生物学， 2010， 博士

【摘要】 柘林湾位于粤、闽两省沿海交界处,海域面积68-70 km²,是广东省的大规模海产增养区之一。由于具有良好的避风条件,自上世纪八十年代末以来,柘林湾海水养殖业发展迅速,养殖规模不断扩大。增养殖业的快速发展以及陆源排污排废的影响,使该湾富营养化达到了较高水平,导致有害赤潮的发生（如1997年底发生的棕囊藻Phaeocystis pouchetii赤潮）,给当地渔业生产和生态环境造成严重的危害。为探讨生态退化和有害赤潮发生的原因,自2000年5月至2004年4月对柘林湾生态系统的结构及其功能进行了较长时间尺度（共4个调查年度）的综合性调查。本文是此次综合性调查的研究成果之一,重点研究浮游动物群落结构的划分及其与环境因子之间的相互关系,主要内容有:（1）利用Kruskal-Wallis方差分析（Analysis of variance,ANOVA）对柘林湾浮游动物的种类组成、总个体数、生物量、多样性、均匀度以及水温和盐度的年际差异和空间差异进行详细研究。（2）运用自组织神经网络（Self-organizing map,SOM）方法对柘林湾浮游动物的调查结果进行群落划分;确定各群落的种类数、多样性指数和均匀度;采用优势度（Dominance,D）和指示种系数（Indicator value index,IVI）方法分析确定各群落的优势种和指示种,其中,各群落中优势度D>0.02的浮游动物定为优势种,指示种指数IVI>25%的浮游动物定为指示种;利用方差分析方法对各群落的环境特征及差异性进行分析。（3）利用典范对应分析（Canonical correspondence analysis,CCA）方法探讨浮游动物群落及它们与各种环境因素之间的关系,所用理化生物因子均采用表、底平均值。由于2001年5月以前的调查数据的环境参数不全,用于SOM和CCA分析的数据均为2001.5-2004.4的数据。相应地,4个调查年度被划分为:第一调查年度（2000.5-2001.4）,第二调查年度（2001.5-2002.4）,第三调查年度（2002.5-2003.4）,第四调查年度（2003.5-2004.4）。本文的数学处理和数学模型由数学软件MATLAB编程完成,主要结果如下:柘林湾浮游动物多样性特征整体上表现为种类较多（共79个种类）、生物多样性（1.62±0.26）和均匀度（0.70±0.09）偏低的特点。调查期间,柘林湾总共79个种类中有65个种类的个体数在浮游动物总个体数中所占百分比均小于1%,并且这些百分比的总和仅为10.22%;而柘林湾3种最重要的优势种强额拟哲水蚤Paracalanus crassirostris（占28.05%）、短角长腹剑水蚤Oithona brevicornis（占20.81%）和鸟喙尖头蚤Penilia avirostris（占5.07%）在浮游动物总个体数中所占比例合计则高达53.93%。根据回归分析结果,这3种优势种与均匀度月均值都成负相关关系（r = -0.78,p<0.01;r = -0.78,p<0.01;r = -0.53,p<0.01）,表明柘林湾生物多样性和均匀度相对较低,与柘林湾海区种间分布不均匀、优势种突出、少数种类在整个浮游动物群落中占绝对优势地位有关。根据Kruskal-Wallis方差分析结果,调查期间柘林湾浮游动物的种类数年均值、总种类数、总个体数和多样性指数在年际变化方面有显著差异（p<0.01）,并且呈逐年下滑趋势。这可能与华南地区气温增暖和气候异常有关。同时,Kruskal-Wallis方差分析也表明,柘林湾浮游动物各数据指标在站位间也有显著差异性（p<0.05）。具体结果:浮游动物总个体数、生物量、种数和多样性指数都表现为湾外高于湾内（p<0.05）、非养殖区高于养殖区（p<0.05）的空间分布格局;东部（S₃-S₄）与西部（S₂）之间的浮游动物总个体数和种数有显著差异（p<0.001）,但生物量和多样性指数之间没有显著性差异（p>0.05）。其中,湾顶西部水交换能力最弱和陆源污染压力最大的三百门港S2站和大规模网箱渔排养殖区S6站的生产力最低,说明陆源污染与海水增养殖的二次污染均对浮游动物的数量有重要影响。SOM方法将柘林湾浮游动物群落划分为有明显差异的6个群落,即群落I（近岸暖水群落）、群落II（广布群落）、群落III（近岸中营养群落）、群落IV（近岸富营养群落）、群落V（河口低盐群落）和群落VI（外海高盐群落）。其中,生活在湾外水质相对较好的外海高盐群落是调查海域的优势群落,也是种数、多样性最丰富的群落,其优势种包括强额拟哲水蚤、短角长腹剑水蚤、浮游幼体（pelagic larvae）、拟长腹剑水蚤（Oithona similis）、鸟喙尖头蚤、锦丽哲水蚤（Calocalanus pavoninus）、肥胖三角蚤（Evadne tergestina）、被囊类（tunicata）、小拟哲水蚤（Paracalanus parvus）和尖额真猛水蚤（Euterpina acutifrons）;分布在湾内富营养海域的近岸富营养群落则是种数及多样性最贫乏的群落,其优势种是蔓虫类幼体（cirriped larvae）和小盘盔头猛水蚤（Clytemnestra scutellata）。指示种分析表明,群落I、V和VI分别有7个、1个和7个指示种,而群落II、III和IV则没有指示种。群落间的这些差异与柘林湾的环境退化关系密切,尤其是陆源排污、养殖区水面上和水体中各类增养殖设施的设置和使用,均对浮游生物的时空分布有重要影响。对6个群落环境特征的方差分析结果表明,调查期间水温（Temp）、盐度（Sal）、硅酸盐（Si）、溶解无机磷（DIP）、铵氮（NH₄）、亚硝氮（NO₂）、硝氮（NO₃）和浮游植物密度（Phy）8个环境因子于群落间的数据变化存在明显差异（p<0.01）。这表明,柘林湾浮游动物的聚集模式和群落特征与这8个环境因子密切相关。其中,群落IV（湾顶西部的三百门港口及养殖区附近）环境因子的数据变异幅度最大,说明该区域人类活动频繁,污染最为严重。CCA的分析结果不仅证实了上述结果,而且还区分出上述环境因子对浮游动物群落影响的强弱。按照降序排列,水温、营养盐（DIN和Si）、盐度和浮游植物密度是浮游动物时空分布的主要决定因素。CCA分析还发现,柘林湾调查海区的水温和营养盐（氮、磷）逐年升高,柘林湾海区大多数对外界环境比较敏感的浮游动物种类已逐渐消失（共35个种）,广温、广盐性的广布种成为海区的优势种,对富营养化有很强的耐受能力、对频繁的人类活动有很好适应能力的耐污种则成为富营养盐海域的优势种。这也提示全球变暖、当地气候变化、浮游植物的季节性变化、陆源径流以及人类干扰（如来自海水养殖业和港口的污染等）等都可能对柘林湾的浮游动物群落形成有直接或间接的影响。更多还原

【Abstract】 Zhelin Bay, covering 68-70 km², is one of the most important bays for large-scale marine culture in South China. Since 1980s, as a good place for typhoon-sheltering, it has seen its mariculture develop rapidly. Hence, together with traditional nutrient from the waste discharge and agricultural activities, the increasingly intensive aquacultural activities accelerated the eutrophication during the past decade, thus in turn impeded aquacutural production, e.g., the large-scale of harmful algal blooms （Phaeocystis） occurred at the end of 1997. The degenerative and eutrophic environment has made caged fish culture much tougher, bringing huge economic loss, but this problem was paid little attention to and few studies were done about it. From May 2000, our group conducted an ecological investigation around Zhelin Bay, where we monthly sampled the phytoplankton, zooplankton, nutrients, water temperature, salinity, and other environmental variables. In this study, zooplankton communities and their relationships to environmental factors were researched at 9 stations in Zhelin Bay from May 2000 to April 2004.The aim of this work was to （1） study the zooplankton composition, the yearly variation and the spatial differances of species number, abundance, biomass, diversity and evenness throughout the 4-year period, （2） identify the zooplankton community structure and the dominant species and indicator species for each community, and （3） investigate the relationship between zooplankton community and environmental parameters. Communities, however, are difficult to analyze since the data consist of diverse taxa in a non-linear way. Therefore, a self-organizing map （SOM） was utilized to classify the zooplankton communities, and their relationships to environmental factors were analyzed through canonical correspondence analysis （CCA）. An average from the water surface and bottom was taken for all environmental factors in the analysis. Since some environmental factors were absent during the course from May 2000 to April 2001, datasets used for SOM and CCA analyses were those from May 2001 to April 2004. Correspondingly, the 4-year study period was divided as follows: the first study period （May 2000-April 2001）, the second study period （May 2001-April 2002）, the third study period （May 2002-April 2003）, and the fourth study period （May 2003-April 2004）. Results as following:A total of 79 taxa, including 65 species of copepods, 4 species of cladocerans were found throughout the study period, among which calanoid Paracalanus crassirostris, cyclopoid Oithona brevicornis and cladoceran Penilia avirostris were the most abundant species, contributing 28.05%, 20.81% and 5.07% of the total zooplankton abundance, respectively. Besides, in terms of species number and density, copepods were the most abundant group （69.76%）.Based on results of Kruskal-Wallis ANOVA, samples from the outer bay and stations at the edges of the large-scale caged-fish farm had significantly greater abundance, biomass, species number and diversity than those from the inner bay （p<0.05） and the station in the center of the largest caged-fish farm （p<0.05） with the lowest values observed in S2, which is frequently perturbed by human activities. Samples from eastern boundaries of the bay had significantly greater abundance and species number than those from western boundaries （p<0.001）, while biomass and diversity had no significant differences between the eastern and western parts of the bay （p>0.05）.As for the yearly variation, the Kruskal-Wallis ANOVA results revealed that the abundance, biomass, species number and diversity had significant differences among the investigated years （p<0.01）. Moreover, the abundance, biomass, speceis richness and diversity all showed a decreasing tendency through the investigation, which might be attributed to the increasing of mean temperature and the abnormal weather in southern China.Six clusters with dominant species compositions and indicator species were distinguished by SOM method, i.e. cluster I （Neritic warm water community）, cluster II （Eurytopic community）, cluster III （Neritic mesotrophic community）, cluster IV （Neritic eutrophic community）, cluster V （Estuarine low-saline community） and cluster VI （Pelagic high-saline community）. The pelagic high-saline community, which occurred in the outer bay with relative good water quality, was the dominant community in the study area. The dominant species for this community were Paracalanus crassirostris, Oithona brevicornis, pelagic larvae, Oithona similis, Penilia avirostris, Calocalanus pavoninus, Evadne tergestina, tunicata, Paracalanus parvus and Euterpina acutifrons. However, the neritic eutrophic community, which occurred in eutrophic waters, was the poorest community, and dominated by cirriped larvae and Clytemnestra scutellata. Furthermore, seven, one and seven indicator species were identified for cluster I, V and VI, respectively, while no indicator species were observed in cluster II-IV. The differences among clusters could be mainly ascribed to the changes in environmental factors; especially the intensive aquaculture structures suspended on waters and in waters have a great impact on the distribution patterns of organisms in the bay. Differences of environmental variables for each cluster derived from the SOM were analyzed by ANOVA. The ANOVA on environmental variables in the 6 clusters gave significant differences （p<0.05） for temperature （Temp）, salinity （Sal）, Si, DIP, NH₄, NO₂, NO₃ and phytoplankton （Phy）, showed highly significant differences among clusters （p<0.01）, suggesting the existence of relationships between these variables and zooplankton communities. Moreover, each variable in cluster IV （aquaculture areas situated at the inner and western parts of the bay） showed larger variation than that in other clusters, which might be attributed to the influence of anthropogenic activities in this area, such as discharge from domestic and mariculture waste from aquaculture effluents.The CCA analysis not only confirmed the above findings, but also showed that, with descending importance, water temperature, nutrients （DIN and Si）, salinity and phytoplankton were the main determinants of spatial and temporal distributions of zooplankton in Zhelin Bay. Moreover, the CCA analysis revealed that the eurytopic species, with the deterioration of eutrophication, has become the dominant species in Zhelin Bay, while species that are vulnerable to organic pollution decreased or disappeared completely. These results also reflected a shift in zooplankton community structure due to environmental deterioration, which implies that the zooplankton community in Zhelin Bay could be directly or indirectly affected by global warming, local climate fluctuations, seasonal cycles of phytoplankton, river discharge which alters salinity distribution and residence time of plankton, and other environmental variables that affected by the pollution originated from land, mariculture and other human activities.更多还原