Effects of changing land use on the microbial water quality of tidal creeks     

DiDonato GT  Stewart JR  Sanger DM  Robinson BJ  Thompson BC  Holland AF  Van Dolah RF 《Marine pollution bulletin》2009,58(1):97-106

Population growth along the southeastern United States coast has precipitated the conversion of forested watersheds to suburban and urban ones. This study sampled creeks representing forested, suburban, and urban watersheds along a longitudinal gradient for indicators of water quality, including traditional indicator bacteria (fecal coliforms and enterococci) and alternative viral indicators (male-specific and somatic coliphages). Tested microorganisms were generally distributed with highest concentrations in creek headwaters and in more developed watersheds. The headwaters also showed the strongest predictive relationship between indicator concentrations and urbanization as measured by impervious cover. A seasonal pattern was observed for indicator bacteria but not for indicator viruses. Coliphage typing indicated the likely source of contamination was nonhuman. Results suggest that headwater creeks can serve as sentinel habitat, signaling early warning of public health concerns from land-based anthropogenic activities. This study also implies the potential to eventually forecast indicator concentrations under land use change scenarios.  相似文献   

Longitudinal patterns of genetic diversity and larval density of the riverine caddisfly Hydropsyche orientalis (Trichoptera)     

Kozo Watanabe  Michael T. Monaghan  Tatsuo Omura 《Aquatic Sciences - Research Across Boundaries》2008,70(4):377-387

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Substrate-specific macroinvertebrate diversity patterns following stream restoration     

Sonja C. Jähnig  Armin W. Lorenz 《Aquatic Sciences - Research Across Boundaries》2008,70(3):292-303

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九寨沟保护区植被景观变化与生境破碎化研究   总被引：3，自引：0，他引：3  

郝云庆  江洪  王金锡  金静  马元丹 《地理科学》2009,29(6):886-892

根据1974、1994和2002年三个时段卫星影像,将土地覆盖类型划分为针叶林、针阔叶混交林、落叶阔叶林、灌丛、草地、裸地和水体7个类型。研究发现,九寨沟森林面积、特别是针叶林面积减少,各景观类型破碎化程度也在增大。与1974~1994年间森林丧失平均速率相比,1994~2002年间森林丧失速率明显放缓。第二期灌丛面积平均增长速率是第一期的3.5倍。随着生境破碎化的加剧,许多珍稀保护生物的前景变得难以预测,应以审慎的态度来对待所谓的“生态旅游”。  相似文献   

植物地境及物种地境稳定层   总被引：9，自引：0，他引：9  

徐恒力  孙自永马瑞 《地球科学》2004,29(2):239-246

植物地境是其生境的重要组成部分.地境结构的系统分析应作为探索植物与其地境生态关系的重要手段之一.植物地境具有鲜明的耗散结构特征, 内部的宏观稳定性和层次性是适应外界环境的自组织结果, 并与植物根群的“层片”结构相契合.每一“层片”代表一个特定的地下小环境.若地境具有多个“层片”, 说明该地境拥有可被多种植物利用的多样小环境.根群作为根系的主功能区, 是联系植物与地境的纽带.与植物的根系相比, 根群的“层片”现象更清晰.通过根群的“层片”, 不同植物实现资源分割, 避免过激竞争, 能够长期共存.基于地境耗散结构特征分析和各物种根群所处深度范围的统计结果, 首次建立了物种地境稳定层的概念.某一物种根群所处的位置即为该物种的地境稳定层.物种地境稳定层可作为地境生态功能分层的基本单位.较之地境全剖面各指标的平均值, 地境稳定层内理化指标组态更为真实地反映了植物生存的地下环境, 可用以确定物种的生存域; 不同植物的生理和生活习性是对其稳定层内指标组态量值及动态变化规律的一种响应; 地境所能提供的稳定层的多寡及组态对地表植物群落的结构具有一定的控制作用; 地境稳定层的消失和产生, 可导致对应物种的消亡和入侵, 造成植物群落的演替.   相似文献   

Physical and Human Factors Influencing Potential Fish Habitat Distribution along a Mountain River, France     

H. Piegay  A. Thevenet  G.M. Kondolf  & N. Landon 《Geografiska Annaler: Series A, Physical Geography》2000,82(1):121-136

Potential fish habitat along the Drôme River, France, is a function of the distribution of large woody debris, boulders, undercut banks, gravel substrate, and pools. The distribution of these features is, in turn, a function of channel geomorphology, watershed and riparian forest characteristics. We conducted field work and analysed aerial photographs for 190 elementary segments of 500 m length along the Drôme River's 95 km course from the Alps westward to its confluence with the Rhône River near Loriol. The Drôme River does not follow the classic pattern of a monotone downstream decrease in gradient and change in channel characteristics. Although channel gradient, braided index and channel incision all decrease downstream, stream power is independent of longitudinal distance. These variables are largely controlled by geomorphic, human or hydrologic factors at the reach scale. Potential fish habitat richness decreases downstream, but individual habitat variables affecting habitat richness do not necessarily decrease downstream, many being controlled by local factors rather than by position along the continuum. Large woody debris is more abundant in braided reaches located directly downstream of confluences with main tributaries or downstream input sites. Boulders are most abundant downstream of failed bank protection works or in gorges. To improve fish habitat in the Drôme River, we recommend taking a long-term and large-scale perspective. Because structures placed in this unstable channel are likely to be washed downstream, we propose to emulate natural river dynamics and to permit large woody debris to enter the channel in unstable reaches via bank erosion, and that this debris not be removed (as is routinely done now) but permitted to migrate downstream through the system, creating fish habitat en route.  相似文献   

Response of Spartina alterniflora Vegetation to Oiling and Burning of Applied Oil     

C.W Lindau  R.D Delaune  A Jugsujinda  E Sajo 《Marine pollution bulletin》1999,38(12):781-1220

A field study evaluated Spartina alterniflora sensitivity to oiling and to in situ burning of applied crude oil. Experimental plots (2.4 m × 2.4 m × 0.6 m) were constructed in the salt marsh for control, oiling (natural clean-up) and oiling/burning treatments. South Louisiana Crude was applied to oiling and oiling/burning treatment plots at 2 l m⁻² and the burn conducted. S. alterniflora responses (height, live stem density, carbon fixation and biomass) were measured for 50 weeks after the August burn. Oiling and oiling/burning had short-term detrimental effects on the salt marsh. One year after the late summer burn, S. alterniflora responses measured in the oiled and oiled/burned plots were not significantly different compared to control values. Results suggest that, under our experimental conditions, intervention may not be required for marsh recovery. However, if spill conditions require a rapid response to control contaminant spread or protect other sensitive resources, burning may be a clean-up operation to consider.  相似文献   

广东二叠纪动物群的古生态     

覃秀兰  竺维彬 《煤田地质与勘探》1992,20(5):7-11

广东二叠纪地层分布广泛,尤以粤北、粤东、粤西北发育最好,也是广东的主要含煤地层。二叠纪动物群繁盛,大量的动物化石大多采自泥岩和灰岩,计有138属421种,主要包括（?）、腕足、双壳类、头足类和牙形刺等。根据动物的生态特征、分布状况以及沉积环境,广东二叠纪古生物地理区可分成连阳区和粤北-粤东-粤中区,同时依照不同的年代、不同的地区有12个动物群。这些动物群总属于浅海相和海陆交互相的古生态环境。   相似文献   

中国近海浮游介形类大尺度生态研究　Ⅴ.浮游介形类群落生境地理位置的季节性变迁     

林景宏  陈瑞祥  郭凤飞 《海洋学报》1998,20(5):109-113

综合分析黑潮、南海暖流、黄海冷水团、对马暖流、闽浙沿岸流、粤东沿岸流、季风和径流对中国近海影响的季节性差异,从而导致中国近海浮游介形类的群落生境地理位置随之进行季节性的变迁。本文选择差异甚大的夏、冬两季进行分析。  相似文献   

安徽升金湖国家级自然保护区水鸟生境适宜性变化   总被引：3，自引：2，他引：1  

杨李  董斌  汪庆  盛书薇  韩文妍  赵俊  程明伟  杨少文 《湖泊科学》2015,27(6):1027-1034

水鸟是湿地生态系统健康的指示生物,人类活动对其影响日益严重.研究自然保护区内的水鸟生境适宜性变化可以为湿地恢复提供帮助.通过层次分析法确定水鸟生境影响因子的权重,建立生境适宜性指数模型,根据TM遥感影像图和相关数据计算出安徽省升金湖国家级自然保护区1986-2011年5个年份的水鸟生境适宜指数,并结合GIS空间分析生成的水鸟生境适宜性分级图,分析升金湖建立保护区后水鸟生境适宜性变化.结果表明:升金湖地区在1986年建保护区后的几年间水鸟生境适宜性相对平稳,但是仍然有较为明显的下降;1990s后期,该地区水鸟生境适宜性开始显著恶化,一直持续到2000年之后才有小幅度的回升.水鸟生境适宜性最好的区域由片状分散逐渐转变成小范围聚集,适宜区域也在由实验区和缓冲区向核心区迁移的过程中显著缩减.本文还讨论了在研究中存在的不足,并提出一些恢复水鸟生境的建议.  相似文献