938 resultados para ECOLOGICAL STUDIES


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Hawaii’s coastal marine resources have declined dramatically over the past 100 years due to multiple anthropogenic stressors including overfishing, coastal development, pollution, overuse, invasive species and climate change. It is now becoming evident that ecosystem-based management, in the form of marine protected areas (MPAs), is necessary to conserve biodiversity, maintain viable fisheries, and deliver a broad suite of ecosystem services. Over the past four decades, Hawaii has developed a system of MPAs to conserve and replenish marine resources around the state. These Marine Life Conservation Districts (MLCDs) vary in size, habitat quality, and management regimes, providing an excellent opportunity to test hypotheses concerning MPA design and function using multiple discreet sampling units. NOAA/NOS/NCCOS/Center for Coastal Monitoring and Assessment’s Biogeography Branch used digital benthic habitat maps coupled with comprehensive ecological studies between 2002 and 2004 to evaluate the efficacy of all existing MLCDs using a spatially-explicit stratified random sampling design. The results from this work have shown that areas fully protected from fishing had higher fish biomass, larger overall fish size, and higher biodiversity than adjacent areas of similar habitat quality. Other key findings demonstrated that top predators and other important fisheries species were more abundant and larger in the MPAs, illustrating the effectiveness of these closures in conserving these populations. Habitat complexity, protected area size and habitat diversity were the major factors in determining effectiveness among MPAs.

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Large (>458 mm) striped bass (Morone saxatilis) are dominant predators in Chesapeake Bay. In recent years, the Chesapeake Bay stock of striped bass has increased dramatically, raising concerns about their predatory impact and their forage requirements. In response to these concerns and the need for more recent ecological studies, this investigation was conducted to characterize feeding habits of large striped bass in Chesapeake Bay. Stomach contents from 1225 striped bass from 458 to 1151 mm TL were examined in the spring and fall of 1997 and 1998. Striped bass consumed 52 different species of vertebrates and invertebrates; however, only a few species of clupeoid and sciaenid fishes dominated diets across both the seasons and size ranges of striped bass examined. Of finfish species, menhaden (Brevoortia tyrannus) was the dominant prey in most areas and gizzard shad (Dorosoma cepedianum) replaced menhaden in importance in lower salinity waters. Spot (Leiostomus xanthurus) and other sciaenid fishes and anadromous herrings (Alosa spp.) also contibuted large percentages of striped bass diet. Although pelagic schooling fishes formed the majority of the diet, benthic fishes contributed a higher percentage to the diet than in previous studies of striped bass diet composition.

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The appendices include the workshop agenda, a list of poster presentations, and a list of attendees.

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菌根是一种植物营养根与土壤真菌形成的共生体,在自然界中分布广泛。外生菌根真菌是菌根真菌的重要类群,其宿主植物约占陆地植物总数的3%左右。由于外生菌根真菌的宿主植物常常是一些生态系统的优势种和建群种,并且这些真菌还参与了许多森林生态系统的有机和无机元素循环、物种的竞争和共存、生物多样性的维持、生态系统的演替等过程,因而对外生菌根真菌的研究有助于对这些生态系统维持和演替机制的深入理解。本文通过外生菌根真菌的种类鉴定和多样性,外生菌根真菌种群的遗传结构,外生菌根真菌群落的结构、空间格局及植物-菌根真菌空间关系,外生菌根真菌接种对植物生长和竞争的影响等四个方面的研究,使我们对这一地区的外生菌根真菌的种类组成、空间分布和传播规律、年度变化、以及对植物群落组成和多样性的影响等方面,有一个初步了解。 外生菌根真菌的鉴定和种类组成是进行菌根真菌研究的前提之一。在第一章中,主要通过子实体形态分类和分子方法,对大型真菌的种类进行了鉴定。在对东灵山和都江堰森林的调查中分别发现的大型真菌106种和98种,菌根真菌比例分别为44.3%和69.4%,木生真菌比例分别为16%和10.2%。按Fellner的评价标准,两个森林群落均属于健康的生态系统。我们应用ITS-RFLP和ITS序列比较的方法对地上子实体、地下菌根及分离培养的菌种进行了种类鉴定和分析。结果表明,ITS-RFLP可以用来进行外生菌根真菌的种类鉴定,而序列分析能够提供更为可靠的信息。二者的结合,可以使我们建立菌根真菌分子数据库成为可能。 种群遗传结构的研究包括种群中个体的空间分布和亲缘关系等方面,有助于加深我们对种群的生殖和传播方式,菌根真菌与风、雨、动物等生态因子的关系等方面的理解。第二章主要以两个外生菌根真菌种群为例,对种群遗传结构中空间距离与遗传相似性的关系、种群结构的年度变化等方面进行了探讨。正红菇(Russula vinosa)种群具有较高的遗传多样性,每个子实体来自不同的克隆。空间距离-遗传相似性关系和空间格局分析的结果均表明,这一正红菇的种群结构可能是由短距离孢子传播产生的,而不可能是无性生长或长距离孢子传播形成的。在对隐花青鹅膏菌(Amanita manginiana)连续两年的种群结构进行了研究中,种群的每一个子实体也均来自不同的克隆。遗传相似性分析、AMOVA、遗传相似性-空间距离关系的结果均显示,这两年的种群在遗传相似性和种群结构上均具有显著差异。对此的一个合理的解释就是,这一外生菌根真菌种群来说,其个体由有性孢子发育为子实体的时间可能超过一年,因而2001和2002年的个体并非同一种群的连续世代。 外生菌根真菌群落可以定义为在一定地理范围和时间尺度内不同外生菌根真菌种群的组合。对外生菌根真菌群落的研究有助于揭示森林生态系统中菌根真菌与植物、菌根真菌与环境因子、以及菌根真菌之间的相互关系。在第三章中,我们应用点格局的分析方法和二元逻辑回归分析对外生菌根真菌的主要类群,即鹅膏菌科,牛肝菌科和红菇科,的空间格局及其与周围(5×5米样方)树种组成的关系进行研究。结果表明,某些树种与特定类群菌根真菌的子实体出现有负相关,而三个类群的外生菌根真菌在克隆生长上的差异并不是子实体空间分布的决定因素。而在较小尺度上(450平方米样方)研究也表明,三个主要外生菌根真菌类群的空间分布为聚集半径不等的集群分布,并且其空间分布不依赖于木本植物的分布。外生菌根真菌主要类群在空间分布上具有相互抑制的特点,而抑制能力的大小可能与菌根真菌地下菌丝体的分布范围及连续性有关。 外生菌根真菌的盆栽接种实验通常用来验证菌根真菌-宿主植物的相互关系,不但有理论意义,也是大田实验和大规模生产应用的基础。第四章中进行了两个实验,对外生菌根真菌多样性与宿主植物生长的关系以及菌根真菌与植物之间竞争平衡的关系进行了初步研究。在外生菌根真菌多样性对马尾松生长影响实验中,菌根真菌接种并未显著促进马尾松幼苗的生长和生物量积累,不同的菌种与地上、地下生物量的积累存在不同(正或负)的相关关系。外生菌根真菌的多样性水平与马尾松幼苗的针叶数量存在显著的正相关,并且随接种时间的延长相关关系更为显著。外生菌根真菌多样性水平还与马尾松幼苗地下生物量的累积呈显著的正相关关系。在外生菌根真菌对三种植物的竞争平衡和共存的影响实验中,外生菌根真菌接种没有显著促进马尾松幼苗的生长,但对漆树和枹栎幼苗的生长有显著影响。外生菌根真菌接种能够在两个外生菌根真菌宿主植物竞争中降低枹栎对马尾松的优势,在马尾松和漆树的竞争中降低马尾松的优势,并促使枹栎与漆树(一个外生菌根真菌宿主和一个非宿主植物)的竞争处于不稳定状态。 本文首次通过生态学的角度对外生菌根真菌的物种多样性、种群结构、群落中的空间格局、以及外生菌根真菌与植物生长的关系进行了较为全面的研究。在大型真菌的多样性方面,菌根和木生真菌比例的引入可以完善森林生态系统的健康评价体系,而分子数据库的建立使对大型真菌尤其是外生菌根真菌多样性的长期监测成为可能;在种群遗传结构方面,本文验证了红菇属和鹅膏菌属克隆较小的特点,以及红菇属菌根真菌以短距离孢子传播为主的繁殖特性,并首次从生活史特点的角度解释菌根真菌的种群结构的年度差异;在菌根真菌群落的空间格局方面,本文首次应用二元逻辑回归和点格局分析的方法研究外生菌根真菌的空间分布及菌根真菌-植物关系,并发现三个类群的外生菌根真菌在子实体分布上具有相互排斥的特点;在控制实验中,本文首次研究了菌根真菌接种的多样性水平对宿主植物的影响,首次研究了外生菌根真菌接种对三个物种之间竞争与共存的影响。虽然这些研究在很多方面都仅得到初步的结果,但我们希望这些探索可以为今后对外生菌根真菌的生态学研究提供有益的启示。

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The Annual report covers Research work of the Organization carried out during the period 1975. Its explains the following research work: Haplochromis Studies, Electrophoresis,The Ecology of Haplochromis in the northern waters of Lake Victoria Limnology, Aquatic Pollution and Biochemical Studies The Biology of Synodontis in Lake Victoria Riverine Fisheries, Inshore Fishery of the Kenyan-Waters of Lake Victoria Biostatistics, the Inshore Fisheries of the Western part of Lake Victoria, The Offshore Fisheries of Kenyan Waters of Lake Victoria Lake Mobutu Sese Seko: Stock Assessment and Ecological Studies Fishery Economics, The Biology of Bagrus docmac in Lake Victoria Fishery Resource Surveys of Lake Wamala and Kijanebalola

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Ecological studies on macrozoobenthos were conducted in two small plateau lakes in the Yunnan-Guizhou Plateau, Southwest China: Xingyun Lake (XL), a eutrophic lake whose main source of primary production was phytoplankton (Chl a=99.76 +/- 24.01 mu g/L), and Yangzong Lake (YL), a mesotrophic lake. Sampling was carried out from October 2002 to May 2004. Altogether 23 benthic taxa were identified in XL and 21 taxa in YL. The density of benthos in XL was much lower than that in YL, but the biomass was about equal in the two lakes, being 1 423 ind/m(2) and 8.71 g/m(2) in XL and 4 249 ind/m(2) and 8.60 g/m(2) in YL. The dominant species were Limnodrilus hoffmeisteri, Branchiura sowerbyi, Aulodrilus pluriseta and Chironomus sp. in XL and Limnodrilus hoffmeisteri, Aulodrilus pluriseta and Bellamya sp. in YL. Seasonal fluctuation occurred, showing richer species in summer and winter, but the density and biomass varied in different ways in the two lakes. Analyses on functional feeding groups indicate that collector-gatherers were predominant, but the relative abundances of other groups were different. Stepwise multiple regression analysis demonstrated that the water depth, conductivity and chlorophyll a were the key factors affecting macrozoobenthic abundance in the lakes.

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Ecological studies on benthic nematodes were conducted in two small, shallow lakes in the middle Yangtze basin, China; Lake Houhu, where the main source of primary production is phytoplankton and Lake Biandantang where it is predominantly macrophytic in origin. Monthly sampling was carried out from April 1996 to March 1997. A total of 36 species of nematodes was found in Lake Houhu and 51 species in Lake Biandantang. The dominant trophic groups of nematodes were algophages in Lake Houhu and bacteriophages associated with omniphages and phytophages in Lake Biandantang. Community analyses based on K-dominance curves, Shannon-Wiener and Simpson diversity indices, demonstrate that the benthic nematodes are more diverse in Lake Biandantang than in Lake Houhu. The results suggest that the abundance of submerged vegetation is essential for maintenance of habitat heterogeneity and biodiversity of nematodes in shallow lakes.

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微型和小型底栖动物是底栖微/小食物网的重要构成。相对浮游生态系统, 迄今国际间对底栖食物网的认知极为欠缺。这一方面是由于微型生物形态和功能上的复杂性和多样性, 另一方面原因在于研究方法的障碍—主要是微型和小型底栖动物的定量提取和定性分析。本研究首先进行了方法学改良, 并应用新方法对底栖微食物网的重要功能类群—纤毛虫原生动物和小型底栖动物进行了不同生境的周年按月采样, 定性及定量研究的同时, 联系环境因子对微型和小型底栖生物的环境监测进行了探讨。 微型和小型底栖生物的定量研究首先涉及到目标生物在沉积物中的有效提取, 目前硅胶液提取是普遍使用的方法, 其中Ludox液主要应用于小型生物, 它不但价格便宜而且比重合适, 因此在常规生态研究中被广为接受。不过, Ludox易与于海水中的阳离子产生凝结而无法直接用于微型生物; 目前唯一直接应用于微型生物提取的是Percoll硅胶液, 但其昂贵的价格使其在常规生态研究中受到极大限制。本研究以价格低廉的Ludox 硅胶液结合定量蛋白银染色 (QPS) 技术开发了一种新的方法, 即Ludox-QPS法。主要流程为: 样品采集与固定、淘洗/稀释降盐、Ludox密度梯度离心、过滤浓缩和琼脂包埋, QPS染色、永久封片及鉴定计数。添加已知数量的纤毛虫至无生物底泥的重获实验表明, 该密度梯度离心的提取率大于94%; 该方法对自然沉积物中纤毛虫的提取率达97.6%, 对沙质、泥沙质和泥质中海洋线虫的提取率分别达97%、96.9% 和97.8%。对比实验表明, 经QPS制片获得的小型动物的丰度和类群数量与传统方法相当或更高, 尤其当小个体虫体占优势时, 该法显示出较传统方法 (导致数量低估) 更为明显的定量优越性。该方法除用于纤毛虫和小型动物的定量分析外, 还具有较高的分类分辨率, 染色后的纤毛虫原生动物大多类群可鉴定到属, 部分可鉴定到种, 以此可在群落水平上研究其生态作用。 根据新开发的Ludox-QPS技术, 在大沽河潮间带依据盐度梯度选定2个站位 (IIQ和营海) 进行了周年按月采样, 对底栖纤毛虫和小型底栖动物进行了定量研究。纤毛虫原生动物在IIQ和营海的年平均丰度分别为2236 inds./10 cm2 和935 inds./10 cm2 (28 inds./ml 和12 inds./ml), 平均生物量分别为119.1 gC/10 cm2和54.2 gC/10 cm2 (1.5 gC /ml 0.7 gC/ml)。丰度的季节变化趋势为: 春天 > 秋天 > 夏天 > 冬天。垂直分布上, 在营海分布于表层0-0.5 cm 的比例为57.1%, 分布于0.5-2 cm、2-4 cm和4-8 cm比例分别为23.1%、11.4% 和8.5%; 13个月中除12月份外, 4-8 cm均有一定数量的纤毛虫分布; 而在IIQ, 97% 的纤毛虫分布在0-0.5 cm, 分布在0.5-2 cm、2-4 cm和4-8 cm比例分别为2.4%、0.4%和0.2%, 4-8 cm的分布只发生在春季和秋季。纤毛虫的多样性季节变化明显, 春秋季物种丰富, 两个站点每毫升沉积物的平均物种数分别为18和6。Two-Way Crossed ANOSIM 分析表明纤毛虫群落在月份间和站点间的差异极其显著。Pseudochilodonopsis sp., Chilodontopsis sp., Euplotes sp.及Prorodon sp.是表征两个生镜中纤毛虫群落的主要类群。 同时, 发现了14个小型生物类群, 其中线虫在IIQ和营海的丰度优势度分别为97.4% 和78.6%。小型动物在IIQ和营海的年平均丰度分别为4793 inds./10 cm2和8915 inds./10 cm2 (60 inds./ml和111 inds./ml), 其生物量分别为1068.8 gC /10 cm2和1790 gC /10 cm2 (13.4 gC/ml和22.4 gC/ml)。小型底栖动物的丰度在IIQ的季节变化为: 夏季 (7888 inds./10cm2) > 秋季 (5447 inds./10cm2) > 春季 (3731 inds./10cm2) > 冬季 (2780 inds./10cm2); 在营海则完全相反: 冬季 (15579 inds./10cm2) > 春季 (10691 inds./10cm2) > 秋季 (6611 inds./10cm2) > 夏季 (4667 inds./10cm2)。小型底栖动物和纤毛虫的相对重要性存在明显的区域和季节差异。 纤毛虫原生动物、小型动物及环境因子的相关分析表明, 纤毛虫的丰度和多样性与温度和盐度及有机质含量显著相关, 与小型动物没有显著相关性; 群落结构分析表明, 温度、有机质和小型动物的丰度的组合与纤毛虫群落丰度的相关系数为0.345; 盐度、脱镁叶绿素、有机质和小型动物生物量的组合与纤毛虫群落多样性的相关系数为0.403。依据海洋线虫和桡足类的比值 (N/C) 推测, IIQ 可能存在严重的有机污染, 营海则存在明显的季节波动, 8月和9月及2月可能是污染最严重的季节, 这种状况在纤毛虫群落结构的CLUSTER聚类中得到验证。虽然目前尚没有形成有关微型底栖生物-纤毛虫原生动物的污染检测的直接依据, 但本研究说明纤毛虫群落的确对环境污染具有一定的感应度, 而且这种感应和利用小型生物的主要类群估算的污染检测 (N/C) 存在一定程度的关联。 90年代早期有关青岛湾有机污染带的研究表明, 经彻底截污后, 其环境状况向良性发展。进一步了解该湾的健康状况, 2006.5-2007.5月对该湾沙质和泥沙质的小型动物进行周年按月采样。小型动物在泥沙质和砂质沉积物中的年平均丰度分别为4853 ± 1292 inds./10 cm2和1528 ± 569 inds./10 cm2; 年平均总生物量分别为1434.1 ± 897.0 gC /10cm2和720.7 ± 353.8 gC/10cm2。沙质底小型生物的丰度季节波动明显, 6月份和12月份最高, 3月份和9月份最低; 泥沙质季节波动不明显, 6月份最高。两个站点均有48%的小型动物分布在0-0.5 cm 表层, 海洋线虫在表层的分布比例分别为48% (泥沙质) 和34% (砂质)。共检获14个小型动物类群, 其中线虫在泥沙质和砂质沉积物中的年平均丰度分别4619 ± 1255 inds./10cm2和1014 ± 376 inds./10cm2, 其丰度优势度分别为95.2%和66.4%。其它在丰度上占优势的类群, 泥沙质依次为多毛类 (1.5%)、甲壳幼体 (1.5%) 和桡足类 (0.7%); 沙质依次为: 甲壳类幼体 (12.6%)、腹毛类 (8.3%) 和 桡足类 (6.2%)。CLUSTER聚类分析表明, 泥沙质和和砂质中小型生物的丰度组成具有64%的相似性。BIOENV分析表明, 温度、盐度、中值粒径和粘土粉砂含量的组合最能解释不同月份之间和不同站位间的差异, 其相关系数为0.614。依据小型生物的丰度和类群组成, 表明泥沙质底尚存一定的有机污染。

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There has been a significant body of literature on species flock definition but not so much about practical means to appraise them. We here apply the five criteria of Eastman and McCune for detecting species flocks in four taxonomic components of the benthic fauna of the Antarctic shelf: teleost fishes, crinoids (feather stars), echinoids (sea urchins) and crustacean arthropods. Practical limitations led us to prioritize the three historical criteria (endemicity, monophyly, species richness) over the two ecological ones (ecological diversity and habitat dominance). We propose a new protocol which includes an iterative fine-tuning of the monophyly and endemicity criteria in order to discover unsuspected flocks. As a result nine « full » species flocks (fulfilling the five criteria) are briefly described. Eight other flocks fit the three historical criteria but need to be further investigated from the ecological point of view (here called « core flocks »). The approach also shows that some candidate taxonomic components are no species flocks at all. The present study contradicts the paradigm that marine species flocks are rare. The hypothesis according to which the Antarctic shelf acts as a species flocks generator is supported, and the approach indicates paths for further ecological studies and may serve as a starting point to investigate the processes leading to flock-like patterning of biodiversity. © 2013 Lecointre et al.