Longitudinal Changes in Fish Assemblages and Water Quality in the Willamette River, Oregon

Abstract

A survey of the fish assemblages between fiver kilometer 283 and 2 of the mainstem Willamette River, Oregon, was conducted in 1983 to evaluate the effects of improved water quality on longitudinal changes in fish assemblages and the usefulness of two indices of fish assemblage quality (index of well being and index of biotic integrity). Physical and chemical habitat quality and fish assemblage quality showed gradual, similar, and expected declines from the upper to the lower river, with only small changes near large point sources of pollution. More fish species, more species intolerant of poor habitat quality, and fewer species tolerant of poor habitat occurred in 1983 than in 1945. Stream order was not a predictor of fish assemblage patterns. A modification of the index of biotic integrity appeared to reflect changes in fish assemblage patterns and habitat quality better than the index of well being. A logical river classification is needed to study and manage 1otic ecosystems efficiently and to organize what we know of them. This classification should provide an improved perspective for thinking about rivers and serve as a guide for understanding relationships among sections of a river, among rivers, and between rivers and their watersheds. Since the 1950s, stream order (Strahler 1957) has been used as a framework for organizing information about 1otic processes and distribution patterns oflotic organisms (Kuehne 1962; Lotrich 1973; Vannote et al. 1980). It has been especially useful for explaining the patterns of fish distribution and diversity in small streams of the eastern and central United States (Kuehne 1962; Harrel et al. 1967; Whiteside and McNatt 1972; Lotrich 1973; Fausch et al. 1984). A formal model of fish assemblage-stream order relationships suggests that the assemblages should change most abruptly at or near places where stream order changes (Lotrich 1973). A corollary of that model is that only subtle changes occur within a single order. The prevailing model more closely resembles that of Fausch et al. (1984), who suggested that assemblages change gradually with order. A third model suggests that fish assemblages change abruptly or gradually because of abrupt or gradual changes in physicochemical habitat (Matthews 1986). Two indices of fish assemblage quality have been proposed. The index of well being (IWB) incorporates two diversity and two abundance estimates with approximately equal weight (Gammon 1976, 1980). The composite value reflects fish assemblage quality more realistically than a single estimate of species diversity or abundance. The index of biotic integrity (IBI) aggregates six speciescomposition metrics, three trophic-composition metrics, and three fish-condition metrics (Karr 1981). Scoring criteria for each metric are based on data from high-quality fish assemblages. Both the IWB and the IBI were developed and tested on fish assemblages in the Mississippi River drainage. Their applicability to the depauperate (in terms of species and families) ichthyofauna of the Columbia River...

Predicting assemblages and species richness of endemic fish in the upper Yangtze River

“…Among them, species richness (SR) is an integrative descriptor of the animal community, because it is influenced by a large number of natural environmental factors as well as anthropogenic disturbances, including the geological history of the area, environmental stability, ecosystem productivity and heterogeneity (Lenat, 1988;Céréghino et al, 2003). For example, Hughes and Gammon (1987) reported that species richness could be as a function of stream order in North American rivers. Hugueny (1989) found that in West Africa, the species richness of a river was related to the surface area of its catchment and its discharge.…”

Influência da urbanização sobre as assembléias de peixes em três córregos de Maringá, Paraná

“…Para as assembléias de peixes, variações na composição, estrutura e distribuição das espécies têm sido associadas com mudanças na morfologia do canal (SCHLOSSER 1982), profundidade, tipo de substrato e corrente (GORMAN & KARR 1978, ANGERMEIER & KARR 1984, com a estruturação da vegetação marginal (JONES III et al 1999, BARRELA et al 2001) e aspectos químicos da água, como concentrações de nutrientes, oxigênio dissolvido (HUGHES 1987, SILVA 1995, HONNEN et al 2001, substâncias cloradas (OSBORNE et al 1981) e metais pesados (TURNPENNY & WILLIAMS 1981).…”

A new framework to evaluate ecosystem health: a case study in the Wei River basin, China

“…While MIWB was based on fish abundance and biomass, it was easy to calculate and widely used in the USA. Hughes and Gammon (Hughes and Gammon 1987) suggested that the IBI and MIWB were applicable to a large western river in the USA. Therefore, it was effective to assess the biological condition in the Wei River.…”