A 30‐month study of the comparative dynamics of the fish populations inhabiting Kelsey Creek, located in the City of Bellevue, Washington, and a nearby pristine control stream suggest that urban development has resulted in a restructuring of the fish community. Environmental perturbations, including habitat alteration, increased nutrient loading, and degradation of the intragravel environment appeared to have a greater impact on coho salmon Oncorhynchus kisutch and nonsalmonid fish species than on cutthroat trout Salmo clarki. Although the total biomass (g/m2) of fish in each stream was similar, its composition differed markedly. Ages 0 and I cutthroat trout were the majority of the fish community inhabiting Kelsey Creek, whereas the control stream supported a diverse assemblage of salmonids of various ages and numerous nonsalmonids. The rapid growth and greater biomass of salmonids in Kelsey Creek (a 2‐year mean of 3.51 g/m2 versus 2.03 g/m2 in the control stream) resulted in a total annual net production of these species of 1.6 to 3.3 times that of the control stream (a 2‐year mean of 7.6 g/m2 versus 3.5 g/m2 in the control stream). Marking and outmigrant studies indicated that environmental disruptions in the urban stream do not result in the displacement of the salmonid inhabitants.
EXECUTIVE SUMMARYIt is the stated purpose of the Endangered Species Act "to provide a means whereby the ecosystem upon which endangered species and threatened species depend may be conserved." Conservation of the Columbia River ecosystem and the diversity of gene pools, life histories, species, and communities that comprise it, should become a major objective of species recovery and fish and wildlife management programs in the Columbia River Basin. Biodiversity is important to both species and ecosystem health, and is a prerequisite to long-term sustainability of biological resources. In this paper, I provide an overview of various approaches to defining, measuring, monitoring, and protecting biodiversity. A holistic approach is stressed that simultaneously considers diverse species and resource management needs. Emphasis is on threatened and endangered species of salmon and their associated habitats.Biodiversity can be organized into compositional, structural, and functional categories; within each category, management opportunities and risks can be identified at different levels of biological organization . The Columbia River Basin comprises an enormous variety of ecosystems and associated biological communities that are undergoing continual change in response to natural and human disturbances. Species are being lost, replaced by non-native species, and introduced or supplemented in increasing numbers. Current trends in habitat degradation (including terrestrial components) and fragmentation must be reversed if salmon are to persist into the future.General guidelines are identified for species recovery and ecosystem conservation. The need to launch a program to inventory, monitor, and assess biological resources for conservation purposes is paramount. Research into the basic ecology of riverine biota is needed, as are better techniques for quantifying biodiversity through the use of indicator species, processes, and spatial units. Consideration should be given to establishing a basin-wide preserve system that guarantees protection of critical habitats and the perpetuation of naturally functioning systems.
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