نتایج جستجو برای: stream habitat

تعداد نتایج: 110551  

Journal: :Molecular ecology 2012
Rike B Stelkens Geoffrey Jaffuel Matthias Escher Claus Wedekind

Salmonid populations of many rivers are rapidly declining. One possible explanation is that habitat fragmentation increases genetic drift and reduces the populations' potential to adapt to changing environmental conditions. We measured the genetic and eco-morphological diversity of brown trout (Salmo trutta) in a Swiss stream system, using multivariate statistics and Bayesian clustering. We fou...

1989
Kelly M. S. Moore Stan V. Gregory

2 Graduate Research Assistant and Associate Professor of Fisheries, respectively, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR, 97331, USA. Abstract: Abundance of resident cutthroat (Salmo clarki) and rainbow (Salmo gairdneri) trout was generally 1.5 to 3.5 times greater in unconstrained reaches than in constrained reaches of Lookout Creek, a fourth-order tributa...

Journal: :Environmental monitoring and assessment 2008
Peter C Smiley Eric D Dibble

The choice of spatial and temporal scale used in environmental assessments may influence the observed results. One method of assessing the impact of stream habitat alterations involves the comparison of response variables among treatment categories (i.e., impacted and unimpacted sites). The influence of spatial resolution on patterns of response variables among treatment categories in assessmen...

2012
Yoichiro Kanno Jason C. Vokoun Kent E. Holsinger Benjamin H. Letcher

We examined habitat factors related to reach-scale brook trout Salvelinus fontinalis counts of four size classes in two headwater stream networks within two contrasting summers in Connecticut, USA. Two study stream networks (7.7 and 4.4 km) were surveyed in a spatially continuous manner in their entirety, and a set of Bayesian generalised linear mixed models was compared. Trout abundance was be...

2004
JOSEPH E. MERZ LEIGH K. OCHIKUBO CHAN

Enhancement projects within anadromous salmonid rivers of California have increased in recent years. Much of this work is intended as mitigation in regulated streams where salmon and steelhead spawning habitat is inaccessible or degraded due to dams, water diversions and channelization. Little research has been done to assess the benefits of spawning habitat enhancement to stream organisms othe...

2002
BRUCE E. RIEMAN

-Bull trout Salvelinus confluentus and other salmonids in the Pacific Northwest are believed at risk of local and regional extinctions because of ongoing habitat loss and fragmentation . Biologists have focused on defining and protecting critical stream channel characteristics, but there is little information regarding the scale or spatial geometry of habitat that may be necessary for the speci...

Journal: :Environmental management 2007
F Douglas Shields Scott S Knight Charles M Cooper

Degradation of warmwater streams in agricultural landscapes is a pervasive problem, and reports of restoration effectiveness based on monitoring data are rare. Described is the outcome of rehabilitation of two deeply incised, unstable sand-and-gravel-bed streams. Channel networks of both watersheds were treated using standard erosion control measures, and aquatic habitats within 1-km-long reach...

2017
Zan Rubin G. Mathias Kondolf Blanca Rios-Touma

Two decades since calls for stream restoration projects to be scientifically assessed, most projects are still unevaluated, and conducted evaluations yield ambiguous results. Even after these decades of investigation, do we know how to define and measure success? We systematically reviewed 26 studies of stream restoration projects that used macroinvertebrate indicators to assess the success of ...

1998
Troy G. Zorn Paul W. Seelbach Michael J. Wiley

–We examined distribution and abundance patterns of 69 commonly occurring fishes at several hundred sites in Lower Michigan streams. We used cluster analysis to group fishes that commonly occurred together at stream sites. These seventeen clusters explained about 39% of the variation in species abundances among the stream sites, providing a reasonable, albeit simplified picture of general assoc...

2016
Xiao Liang Chunyu Liao Michael L. Thompson Michelle L. Soupir Laura R. Jarboe Philip M. Dixon

The importance of E. coli as an indicator organism in fresh water has led to numerous studies focusing on cell properties and transport behavior. However, previous studies have been unable to assess if differences in E. coli cell surface properties and genomic variation are associated with different environmental habitats. In this study, we investigated the variation in characteristics of E. co...

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