Reconciling landscape and local views of aquatic communities: lessons from Michigan trout streams

Abstract

1. Rapidly advancing geographical information systems (GIS) technologies are forcing a careful evaluation of the roles and biases of landscape and traditional site‐based perspectives on assessments of aquatic communities. Viewing the world at very different scales can lead to seeming contradictions about the nature of specific ecological systems. In the case of Michigan trout streams, landscape analyses suggest a predictable community shaped by large‐scale patterns in hydrology and geology. Most site‐based studies, however, suggest these communities are highly variable in structure over time, and are strongly shaped by site‐specific physical and biological dynamics. As the real world is comprised of processes operating both at local and landscape scales, an analytical framework for integrating these paradigms is desirable. 2. Decomposition of variances by factorial ANOVA into time, space and time–space interaction terms can provide a conceptual and analytical model for integrating processes operating at landscape and local scales. Using this approach, long‐term data sets were examined for three insects and two fishes common in Michigan trout streams. Each taxon had a unique variance structure, and the observed variance structure was highly dependent upon sample size. 3. Both spatially extensive designs with little sampling over time (typical of many GIS studies) and temporally extensive designs with little or no spatial sampling (typical of population and community studies), are biased in terms of their view of the relative importance of local and landscape factors. The necessary, but in many cases costly, solution is to develop and analyse data sets that are both spatially and temporally extensive.

Local‐Habitat, Watershed, and Biotic Features Associated with Bull Trout Occurrence in Montana Streams

“…The AIC-based model selection approach we adopted to evaluate competing models allowed us to contrast hypotheses about the factors most important to bull trout occurrence (Anderson et al 2000; see also Thompson and Lee 2000;Harig and Fausch 2002). Coupling investigations of species occurrence in relation to abiotic and biotic factors at multiple scales with methods for ranking their relative importance holds promise for gaining a more comprehensive assessment of landscape and local influences on species distribution patterns (Wiley et al 1997). The associations that we found in our data imply that local-habitat characteristics, the occurrence of brook trout, and the occurrence of bull trout in the main stem are important to the occurrence of bull trout in small tributary streams.…”

Macroinvertebrate prey availability and food web dynamics of nonnative trout in a Colorado River tributary, Grand Canyon

“…The reintroduction of mottled sculpin Cottus bairdi in a Wisconsin stream did not result in any benefits to age 2 and older brown trout (Brynildson and Brynildson 1978), and small brown trout did not exhibit any growth benefits when confined in enclosures with slimy sculpin in a Minnesota stream (Reutz et al 2003). Cause and effect would be difficult to prove without an experimental evaluation because 30-50% of the variation in invertebrate and fish community structure can be explained by large-scale geologic and geomorphic variables (Wiley et al 1997;Blann 2004). Therefore, a more detailed field assessment of differences in diet and prey availability between fast-and slow-growth streams would help test the validity of our modeling results.…”

Longitudinal distribution of the fish fauna in the river Ganga from Gangotri to Kanpur

“…According to Gregory et al (1991) streams are intimately related to their drainage basin, their linear form maximizing the interface between terrestrial and aquatic environments. Climate, geological vegetation, land use and topographic conditions in a basin determine the hydrology and chemistry of receiving waters with direct effects on the stream organism (Wiley et al, 1997). The river Ganga is a holy river of India and has been declared as a National River by the Government of India.…”