辽河口沉积物中古菌和细菌群落结构分析

本研究旨在了解辽河口表层沉积物中古菌和细菌的群落结构组成、多样性及其与环境因子之间的相关性。采用构建古菌和细菌16S rRNA基因文库的方法，应用Illumina Miseq测序技术进行序列分析。结果表明:辽河口表层沉积物中细菌多样性高于古菌多样性，近岸细菌和古菌多样性高于远岸，即河相区（0.8~7.04）细菌多样性高于混合区（13.1~20.7）和海相区（24.2~31.5）；主要古菌群落为奇古菌门（Thaumarchaeota，72.73%）和广古菌门（Euryarchaeota，25.05%），其中泉古菌门（Crenarchaeota，0.001%）只在河相区站位被发现；细菌群落组成中变形菌门（Proteobacteria，61.94%）为该河口的优势菌群，其次为拟杆菌门（Bacteroidetes，11.21%）和酸杆菌门（Acidobacteria，5.59%），其他门类如蓝藻门（Cyanobacteria，3.03%）等比例较小。与环境因子的冗余度分析表明:影响表层沉积物中古菌群落分布的主要环境因子依次为氨盐、泥、酸碱度、盐度、电导率和砂，而细菌群落的分布主要受到溶氧、泥、砂、黏土和总磷的影响。由此可见，不同环境条件下微生物的群落结构存在空间异质性，不同微生物对同一环境条件的响应亦不同。     

中国明对虾混合养殖池塘沉积物微生物群落比较研究

微生物群落在养殖池塘生态系统中发挥着重要的作用，与环境质量及养殖动物的生长和疾病暴发密切相关。为了考察中国明对虾不同混养模式中的微生态状况，本研究基于 16S rRNA 基因的高通量测序技术，比较了 6 种不同中国明对虾混 养池塘沉积物微生物群落的差异。结果表明，6 种混养池塘沉积物的主要微生物均为变形菌门 （Proteobacteria） 和放线菌门（Actinobacteria），与褐牙鲆的混养，会导致变形菌门丰度升高，同时抑制放线菌门的生长。中国明对虾、海蜇、菲律宾蛤仔混养具有最高的沉积物微生物群落丰富度和多样性。通过对微生物功能进行预测发现，化能异养和含硫化合物的呼吸是中国对虾混养池塘沉积物微生物群落的主要功能。中国明对虾、海蜇、菲律宾蛤仔混养沉积物中部分细菌的某特异性富集，可以提高沉积物中溶解氧量并促进化学物污染物的降解。综上所述，中国明对虾、海蜇、菲律宾蛤仔混养模式在 6 种不同中国明对虾混养池塘中微生态状况最佳。     

日照贝类养殖区海水微生物群落结构特征及其影响因素

微生物群落结构和组成差异是反映海洋生态系统环境健康的有效指标,对生态环境监测和管理具有重要意义,同时可以为水产养殖活动提供启示。本文针对日照某贝类养殖区及非养殖区水体环境的微生物群落结构进行了测序和分析,并探讨了环境因子对微生物群落结构和多样性的影响。结果显示,变形菌门（Proteobacteria）是养殖区海水的优势细菌类群,其次是蓝细菌门（Cyanobacteria）和放线菌门（Actinobacteria）。养殖区表层海水中蓝细菌门的相对丰度（P=0.003）以及8 m深度水层中变形菌门的相对丰度（P=0.027）显著高于非养殖区。微生物多样性分析表明,4月至11月养殖区表层及8 m水层的微生物Shannon指数范围分别为5.59～6.92和5.33～7.08,与非养殖区无明显差异,但养殖区的微生物丰富度指数（表层Chao1=1 088.86,8 m深度水层Chao1=1 158.77）略低于非养殖区（表层Chao1=1 108.63,8 m深度水层Chao1=1 210.30）。典型相关性分析（CCA）和Spearman相关性分析结果表明,温度（P=0.003）、盐度（P=0....     

池塘内循环流水养殖下太湖鲂鲌(翘嘴鲌(♀)×三角鲂(♂))肠道微生物群落变化的研究

为研究池塘内循环流水养殖(In-pond Raceway, IPR)模式下太湖鲂鲌(翘嘴鲌(♀)×三角鲂(♂))肠道微生物群落结构的变化,以传统池塘养殖作为对照组,采用16SrRNA高通量测序方法分析了IPR养殖模式下太湖鲂鲌肠道的菌群结构及环境水体微生物多样性的变化。试验结果表明, IPR模式下太湖鲂鲌肠道微生物群落发生了明显的变化,在门分类水平,梭杆菌门(Fusobacteria)成为绝对优势菌,所占丰度为92.47%;对照组的优势菌由梭杆菌门、变形菌门(Proteobacteria)和厚壁菌门(Firmicutes)组成,三者所占的丰度分别为34.45%、33.30%和21.30%。在养殖水环境中,两种养殖模式的微生物群落数均大于肠道样本,且二者优势菌不同;IPR水环境的优势菌为蓝细菌(Cyanobacteria,36.53%),其次为放线菌门(Actinobacteria,24.67%);对照组水体中的优势菌为放线菌门和变形菌门,分别占细菌总数的38.99%和28.15%。多样性指数结果表明,水环境中的微生物群落Shannon多样性指数、Chao1指数高于肠道样本,IPR养殖对象肠道微生物群落多样性最低。本研究结果揭示,池塘内循环流水高密度养殖模式下,太湖鲂鲌的肠道微生物结构发生了一定的改变,微生物群落多样性降低,应注意该模式下养殖对象的肠道健康,加强养殖管理。     

九龙江河口区微生物多样性及群落结构的时空分布

河口区由于其独特的地理环境和理化条件,拥有丰富的微生物资源,在生物地球化学循环中起着重要作用.然而,由于人类活动带来的河口区环境因素改变,引起的微生物群落结构的时空变化目前还知之甚少.本研究选取九龙江河口区7个近年来遭受较为严重人类活动干扰的采样点,分别在丰水期和枯水期采集表层水体,采用流动注射法测定了水体的三氮、电导率、pH值和溶解性磷酸盐等环境参数,采用海水和淡水培养基,基于纯培养技术分析了可培养细菌的总数和分布特征,并通过构建16S rRNA基因克隆文库的方法研究细菌的多样性和群落结构变化.研究表明,变形菌门(Proteobacteria)、放线菌门(Actinobacteria)和拟杆菌门(Bacteroidetes)是各克隆文库中最优势的类群.在河口下游海水区,变形菌门微生物与放线菌门微生物的比例约为2∶1~3∶1,而在河口上游淡水区,变形菌门和放线菌门的比例约为1∶1.在河口下游海水区,α变形菌纲(Alphaproteobacteria)为变形菌门中的优势类群,而在河口上游淡水区,β变形菌纲(Betaproteobacteria)为优势类群.厚壁菌门(Firmicutes)是克隆文库中丰度占第四的类群,说明水体可能遭受畜牧养殖粪便污染.本研究表明,九龙江河口区微生物群落结构受水体盐度、温度、水文情况等时空因子及人类活动造成的营养物浓度上升、动物粪便污染等共同影响,呈现出独特的时空分布特点.     

北极深海沉积物中细菌和古菌群落结构研究

在北极深海沉积物生态系统中,微生物的群落结构由有机质输入、能量的可用性及其他环境因素决定.然而,全球气候变暖及其导致的冰盖提前融化正在影响微生物的多样性.为描述北极深海沉积物中的微生物群落结构及其与环境因素的相关性,我们利用罗氏454对北极深海沉积物样品的16S rDNA扩增子进行了测序,对细菌和古菌群落的丰富度、成分、结构及其系统发育分类地位进行了描述.硫还原和化能有机营养类是细菌群落中的主要类群;而古细菌群落主要是由微生物的关系最为密切的氨氧化奇古菌门(96.66%)和产甲烷古生菌界(3.21%).这项研究描述了北极极点附近深海沉积物(> 3500米)中的微生物多样性,将为以后研究类似环境中微生物代谢过程和途径等功能分析奠定基础.     

三沙湾大黄鱼野生和养殖群体的幽门盲囊微生物群落结构比较分析

大黄鱼（Larimichthys crocea）幽门盲囊呈半封闭结构,保留了部分早期孵化阶段的微生物特征,是用于野生和养殖群体溯源的理想部位。本研究采用高通量测序技术,对三沙湾大黄鱼野生和养殖群体的幽门盲囊微生物的α多样性、核心菌群相对丰度、网络关系等进行分析,构建随机森林模型进行群体溯源分析。结果显示,养殖群体的幽门盲囊微生物有着更多特有操作分类单元（Operational Taxonomic Unit, OTU）,其α多样性显著高于野生群体。幽门盲囊微生物的优势菌群有变形菌门（Proteobacteria）、厚壁菌门（Firmicutes）、拟杆菌门（Bacteroidota）、放线菌门（Actinobacteria）及酸杆菌门（Acidobacteria）,且各菌群在野生和养殖群体中的相对丰度差异显著。微生物网络分析结果显示,野生和养殖群体的幽门盲囊微生物群落结构差异明显,野生群体拥有更高的负边缘/正边缘比率和模块性以及更少的节点数和连接数。基于此,我们构建了随机森林分类群体溯源预测模型,其准确率（Accuracy, ACC）达92.31%,Kappa系数为0.845 2,ROC...     

南海北部水层间及沉积表层细菌群落的比较分析

细菌群落在海洋生物地球化学过程中起着至关重要的作用。分析判别地理距离和环境条件等因素对细菌群落的影响,有助于理解环境变化如何驱动微生物多样性和功能的机制。通过细菌16SrDNA高通量测序的方法,对南海北部水层及沉积表层细菌群落多样性及空间分布进行比较分析,并检验环境因素、地理限制及海底深度等因素对微生物群落的影响。结果表明,约95%的细菌16SrDNA序列归属于γ-变形菌纲、厚壁菌门、蓝细菌门、α-变形菌纲等优势类群。沉积样本中的优势细菌类群主要与粒度、氮(N)等环境参数相关,而水体样本的优势细菌类群与取样深度密切相关。相关性检验结果显示,沉积样本的α-多样性指数与C有着显著的相关关系,而水体样本的α-多样性指数和β-多样性矩阵则显示与取样深度的显著相关;此外,地理距离和海底深度对β-多样性的影响并不显著,这可能与取样空间尺度有关。     

淡化浓海水日晒盐田原核微生物多样性分析

海滨日晒盐田具有稳定且独特的生态系统。淡化浓海水排入盐田制盐,对盐田生态系统的稳定及盐田的可持续发展具有一定的影响。本研究分析天津汉沽淡化浓海水日晒盐田不同季节不同盐度盐池原核微生物多样性现状及群落结构变化,以期为评估淡化浓海水对盐田原核微生物群落影响提供理论依据。采用温度梯度凝胶电泳和序列测定等方法,分析不同月份不同盐度盐池中细菌和古菌的多样性与群落结构变化。分别采用香农-威纳指数、加权丰富度指数和均匀度指数分析盐田微生物群落多样性、丰富度和均匀度。结果表明,淡化浓海水和溴后水中均未检测出细菌和古菌。不同月份不同盐度盐池样本中细菌多样性变化不大,优势菌主要为γ-变形菌门(γ-Proteobacteria)中的Spiribacter salinus和Pseudoalteromonassp.;古菌仅出现在盐度最高的Ⅶ号盐池中,优势古菌为广古菌门(Euryarchaeota)的Halogeometricum sp.。天津汉沽淡化浓海水日晒盐田中细菌的多样性和丰富度较低,春夏两季细菌群落结构较为稳定,秋冬季节细菌群落结构变化明显。盐度不同的盐池中细菌群落结构变化较大,随着盐度逐渐升高, Spiribacter salinus逐渐取代Pseudoalteromonas sp.成为占主要地位的优势菌种。     

东太平洋深海沉积物中DNA的提取及细菌多样性初步分析

以东太平洋海隆附近深海柱状沉积物为材料，通过化学裂解和酶消化相结合的方法提取了沉积物微生物的总基因组DNA，并进行了纯化。结果表明所得到的DNA分子片段大小在21kb左右，纯化后的DNA可直接用于PCR等分子生物学操作。细菌16SrDNAV3可变区的PCR—DGGE图谱展示出15条以上条带，表明深海沉积物中细菌多样性较高，群落结构比较复杂。对其中9条主要条带进行回收、测序和系统发育分析，结果表明所获得的序列分属放线菌门（Actinobacteria），绿弯菌门（Chloroflexi），γ-变形细菌亚门（Gamma—proteobacteria），α-变形细菌亚门（Alpha—proteobacteria）和嗜酸菌门（Acidobacteria）5个大类群。     

珠江口表层沉积物nirS型反硝化微生物多样性

本研究以nirS基因为分子标记,将PCR、克隆文库构建与测序和典范对应分析相结合,对珠江口表层沉积物nirS型反硝化微生物的群落多样性进行了研究。3个站位共获得180个nirS基因克隆子,隶属于62个OTUs,氨基酸序列的相似性在50%—100%之间。各站位OTU分布格局差异明显,范围在19—33之间,表现出高度的多样性。系统进化分析表明,62个OTUs形成了5个类群,分别与河口、海洋沉积物、海岸养殖排放废水、富营养化海湾及海水养殖沉积物等的反硝化微生物聚类在一起,表明珠江口作为海淡水交汇区具有独特的反硝化微生物群落分布格局,同时也指示了珠江口氮污染及富营养化程度。典范对应分析结果表明,盐度、氮相关营养盐水平(PON/TN、NH4-N、NO-N和NO-N)可能是影响其分布格局的重要因素。     

东太平洋中国多金属结核区锰结核样品中微生物群落结构的研究

通过非培养手段研究了东太平洋中国多金属结核区ES0303站点锰结核样品中的微生物群落结构.细菌16S rRNA基因克隆文库的研究结果表明：结核内细菌种群结构复杂,微生物种类丰富且各种群丰度不一（61个OTUs）,其中变形杆菌类群为优势种群,占所有细菌克隆子比例的64%,且主要分布于β/γ-、α-和δ-等3类变形杆菌（Proteobacteria）亚群之中,占比分别为34%、18%和12%.此外还存在包括酸杆菌（Acidobacteria）,放线菌纲（Actinobacteria）,绿弯菌门（Chloroflexi）,厚壁菌门（Firmicutes）,浮霉菌门（Planctomycetes）等在内的细菌类群的分布,克隆子比例依次为9%、7%、8%、2%和5%.古菌16S rRNA基因克隆文库的研究结果表明：古菌的群落结构单一（仅12个OTUs）,全部是由泉古菌海洋类群I（crenarchaeote marine group I,MGI）组成;其中MGI-η类群最为丰富,达到44%,而MGI-α、MGI-ζ和MGI-ε类群的克隆子比例分别为25%、18%和9%,另外还发现2个新的MGI分类类群.相关克隆子的数据库比对和系统发育树分析表明,并未发现已报道的直接参与铁锰氧化还原相关类群的存在,但它们大多数与来自多金属结核来源或深海来源的不可培养微生物具有较高的同源性.进一步的分析表明,锰结核内存在相当数量的氨氧化菌、硫酸盐还原菌、酸杆菌等能够改变pH值的细菌和古菌类群的存在,意味着它们可能在锰结核的形成过程中起到重要的作用.     

采水量对寡营养海域浮游真核微生物分子多样性评价的影响

真核微生物是海洋生态系统中生物多样性高且功能重要的组成部分，但因个体微小且形态特征不明显，传统的分类学方法很难全面评估其多样性。环境DNA结合高通量测序技术为真核微生物多样性研究提供了可靠技术支撑，然而采水量对于评估寡营养海域浮游真核微生物多样性的影响仍知之甚少。本研究在吕宋海峡及菲律宾海盆中设置5个采样点，每个站点各取4个10 L表层海水样品用于真核微生物高通量测序分析。对各站每个重复所获得的真核微生物多样性进行研究，并分析了采水量与真核微生物OTU数量、群落结构及优势种和稀有种之间的关系。研究发现，采水量和真核微生物OTU数量之间呈正相关关系，10 L水所获得的平均OTU数量为40 L水的64%，20 L水可获得82%，30 L水为92%。10 L样品所获得的群落多样性指数显著低于30 L和40 L样品检获的群落，而20 L样品与30 L和40 L样品在多样性指数上无显著差异。随着采水量增加，更多的稀有OTUs被检获，而丰富OTUs数量变化不明显。但统计分析显示，10 L与40 L组样品检获的真核微生物群落结构无显著差异。因此，综合考虑样品的可得性和现场处理时间，最低20 L的采水量可用于评估这一寡营养海域的真核微生物多样性和群落结构特点。     

青山水库轮虫群落结构特征的时空差异对水质变化的影响

为研究青山水库轮虫群落结构特征的时空差异对水质变化的影响,对其进行了四个季度的采样调查。结果共发现轮虫物种30种,分属于9个科,其中优势种为长肢多肢轮虫和针簇多肢轮虫,后者是一种污染指示种,表明水质处于中度污染状态。轮虫平均密度为171 ind./L,平均生物量为0.0158 mg/L。通过对水库理化因子与轮虫群落生物指数进行相关性分析,初步确定水温和溶解氧是青山水库轮虫群落演替的主要影响因子。根据轮虫群落结构聚类分析表明,青山水库分为四大区域。另外,主成分分析结果表明水质的下降可能与营养盐的的增加有关,特别是氮的输入。综合理化指标、营养状态指数、轮虫多样性指数以及优势种指示种等多种评价方法,结果表明2012—2013年青山水库水质属于中度—重度污染之间,营养程度为中度富营养状态,青山水库水环境污染严重。依据理化指标和轮虫群落结构特征来评价水质状况,得到的结果基本一致,因此轮虫可以作为青山水库一个较为理想的检测指标。     

Microbial diversity in polluted harbor sediments II: Sulfate-reducing bacterial community assessment using terminal restriction fragment length polymorphism and clone library of dsrAB gene

Sulfate-reducing bacteria (SRB) are important regulators of a variety of processes in coastal marine sediments regarding organic matter turnover, biodegradation of pollutants, and sulfur and carbon cycles. Yet their community compositions have not been investigated in polluted harbor sediments. This study described the diversity and spatial variation of SRB communities in surface sediments in Victoria Harbor, Hong Kong. The spatial variation of SRB communities was described by terminal restriction fragment length polymorphism (T-RFLP). The results showed that the most diversified terminal restriction fragments were found at polluted sites. In addition, cluster analysis indicated that although the SRB communities were different at the two polluted sites, they were still more similar to each other than to the two more distant reference sites. Based on a dsrAB clone library constructed at a polluted site, diversified SRB were found, represented by 30 Operational Taxonomic Units (OTUs). Upon comparisons among the SRB sequences detected from this study and those in the GenBank, five clades of SRB were found. Three clades belonged to the known families Desulfobacteraceae, Desulfobulbaceae, and Syntrophobacteriaceae. The majority of sequenced clones, which distantly related to sequences in the GenBank, constituted the remaining two unclassified groups, suggesting unique SRB members related to the polluted harbor environment. Statistical analyses indicated that estimated SRB richness correlated with environment factors such as sulfur content, acid volatile sulfate, and redox potential.     

Microbial community structure and diversity in deep-sea hydrothermal vent sediments along the Eastern Lau Spreading Centre

The aim of this study is to investigate microbial structures and diversities in five active hydrothermal fields’ sediments along the Eastern Lau Spreading Centre (ELSC) in the Lau Basin (southwest Pacific). Microbial communities were surveyed by denatured gradient gel electrophoresis (DGGE) and clone library analysis of 16S rRNA genes. The differences in microbial community structures among sediment samples from the five deep-sea hydrothermal sites were revealed by DGGE profiles. Cluster analysis of DGGE profiles separated the five hydrothermal samples into two groups. Four different 16S rRNA gene clone libraries, representing two selected hydrothermal samples (19-4TVG8 and 19-4TVG11), were constructed. Twenty-three and 32 phylotypes were identified from 166 and 160 bacterial clones respectively, including Proteobacteria, Bacteroidetes, Firmicutes, Nitrospirae and Planctomycetes. The phylum Proteobacteria is dominant in both bacterial libraries with a predominance of Gamma-Proteobacteria. A total of 31 and 25 phylotypes were obtained from 160 and 130 archaeal clones respectively, including Miscellaneous Crenarchaeotic Group, Marine Group Ⅰ and Ⅲ, Marine Benthic Group E, Terrestrial Hot Spring Crenarchaeota and Deep-sea Hydrothermal Vent Euryarchaeota. These results show a variety of clones related to those involved in sulfur cycling, suggesting that the cycling and utilization of sulfur compounds may extensively occur in the Lau Basin deep-sea hydrothermal ecosystem.     

北极海洋沉积物细菌和古菌群落结构分析

This study was to investigate bacterial and archaeal community structure of pan-Arctic Ocean sediments by pyrosequencing.In total,investigation of three marine sediments revealed 15 002 bacterial and 4 362 archaeal operational taxonomic units(OTUs) at the 97% similarity level.Analysis of community structure indicated that these three samples had high bacterial and archaeal diversity.The most relatively abundant bacterial group in Samples CC1 and R05 was Proteobacteria,while Firmicutes was dominant in Sample BL03.Thaumarchaeota was the most relatively abundant archaeal phylum in Samples CC1 and R05,and the relative abundance of Thaumarchaeota was almost as high as that of Euryarchaeota in Sample BL03.These two phyla accounted for nearly 100% of the archaeal OTUs.δ-Proteobacteria and γ-Proteobacteria were the two most relatively abundant classes at Proteobacterial class level,and their relative abundance was more than 60% in Samples CC1 and R05.There were also differences in the top 10 relatively abundant bacterial and archaeal OTUs among the three samples at the 97% similarity,and only 12 core bacterial OTUs were detected.Overall,this study indicated that there were distinct microbial communities and many unique OTUs in these three samples.     

高通量测序分析北仑河口红树林潮间带底栖真核生物分布

为了解红树林不同潮位沉积物中底栖真核生物群落分布,基于18S rRNA基因采用高通量测序方法分析了广西北仑河口陆缘、林中和海缘3个潮位红树林沉积物中底栖生物群落结构。结果表明,北仑河口潮间带红树林沉积物中底栖生物多样性丰富,Shannon-Wiener指数变化范围在6. 08～6. 73之间; PCA分析表明潮间带中底栖生物群落差异较大,陆缘红树林中扁形动物、节肢动物和软体动物相对丰度较高,林中区域中纤毛虫、环节动物和轮虫相对丰度较高,海缘红树林中硅藻相对丰度较高;红树林中主要OTUs有桡足类的太平洋纺锤水蚤(Acartia pacifica)、硅藻类的海链藻(Thalassiosira sp.)、纤毛虫类的前管虫(Prorodon teres)、多毛类的小头虫(Capitella sp.)。高通量测序方法能较全面反映红树林区微型/小型底栖生物群落,研究结果为丰富红树林底栖生物群落研究和解析底栖生物在红树林生态系统发挥的作用提供基础数据。     

Parallel structure among environmental gradients and three trophic levels in a subarctic estuary

We assessed spatial and temporal variability in the physical environment of a subarctic estuary, and examined concurrent patterns of chlorophyll α abundance (fluorescence), and zooplankton and forage fish community structure. Surveys were conducted in lower Cook Inlet, Alaska, during late July and early August from 1997 through 1999. Principle components analysis (PCA) revealed that spatial heterogeneity in the physical oceanographic environment of lower Cook Inlet could be modeled as three marine-estuarine gradients characterized by temperature, salinity, bottom depth, and turbidity. The gradients persisted from 1997 through 1999, and PCA explained 68% to 92% of the variance in physical oceanography for each gradient-year combination. Correlations between chlorophyll α abundance and distribution and the PCA axes were weak. Chlorophyll was reduced by turbidity, and low levels occurred in areas with high levels of suspended sediments. Detrended correspondence analysis (DCA) was used to order the sample sites based on species composition and to order the zooplankton and forage fish taxa based on similarities among sample sites for each gradient-year. Correlations between the structure of the physical environment (PCA axis 1) and zooplankton community structure (DCA axis 1) were strong (r = 0.43-0.86) in all years for the three marine-estuarine gradients, suggesting that zooplankton community composition was structured by the physical environment. The physical environment (PCA) and forage fish community structure (DCA) were weakly correlated in all years along Gradient 2, defined by halocline intensity and surface temperature and salinity, even though these physical variables were more important for defining zooplankton habitats. However, the physical environment (PCA) and forage fish community structure (DCA) were strongly correlated along the primary marine-estuarine gradient (#1) in 1997 (r = 0.87) and 1998 (r = 0.82). The correlation was poor (r = 0.32) in 1999, when fish community structure changed markedly in lower Cook Inlet. Capelin (Mallotus villosus), walleye pollock (Theragra chalcogramma), and arrowtooth flounder (Atheresthes stomias) were caught farther north than in previous years. Waters were significantly colder and more saline in 1999, a La Niña year, than in other years of the study. Interannual fluctuations in environmental conditions in lower Cook Inlet did not have substantial effects on zooplankton community structure, although abundance of individual taxa varied significantly. The abundance and distribution of chlorophyll α, zooplankton and forage fish were affected much more by spatial variability in physical oceanography than by interannual variability. Our examination of physical-biological linkages in lower Cook Inlet supports the concept of “bottom-up control,” i.e., that variability in the physical environment structures higher trophic-level communities by influencing their distribution and abundance across space.     

Pollution investigations off the north-east coast of England: Community structure,growth and production of Benthic Macrofauna

The growth of major polychaete and bivalve species inhabiting sandy sediments off the north-east coast of England was examined over a 1-year period in a comparative study of community production in relation to contaminant sources. Background information on site locations, sampling methods and benthic community structure is provided.The polychaetes Spiophanes bombyx, Magelona spp. and Nephtys spp. were major contributors to community biomass at most sites, either individually or collectively. Tellina fabula, Nucula turgida, Venus striatula and other bivalves were only sparsely represented at most sites and growth rates were generally lower than elsewhere. Reduced bivalve populations, together with the presence in high numbers of short-lived polychaete species, may be connected with the vulnerability of bottom sediments to disturbance by water movements in this coastal region.Recruitment patterns were generally similar between sites but showed marked annual variation, with a substantially greater bivalve settlement occurring at the end of the sampling period.Estimates of community production ranged from 3.4 to 7.4 g ash-free dry weight per square metre a year, and showed relatively high turnover rates compared with other regions, which, again, may be related to a greater degree of fluctuation in the physical environment. Production was highest at a site near to the Tees estuary and was accounted for mainly by the polychaetes Nephtys hombergi and Spiophanes bombyx. The concentration of biomass into one or two species may have consequences for the stability of the fauna. However, the results do not appear to indicate any serious effects of pollution, which may suggest that the coastal waters have sufficient capacity to effectively dilute and disperse any harmful constituents of present estuarine efflux.Limitations to the interpretation of field data using conventional methods of sampling and analysis are discussed, and the application of growth studies to investigations of water pollution is advocated.