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Presented at the NABS Annual meeting, Pittsburgh, Pennsylvania, 2002
in Large River Ecology
ZOOBENTHOS ALONG LATERAL AND LONGITUDINAL GRADIENTS IN THE TAGLIAMENTO RIVER (N.E. ITALY).
D.B. Arscott, K. Tockner, and J.V. Ward. Department of Limnology, Swiss Federal Institute of Environmental Science and Technology (EAWAG), 8600-Dübendorf, Switzerland
Aquatic invertebrate abundance, distribution, and richness were investigated along lateral and longitudinal gradients in the Tagliamento River (NE Italy). Twenty-nine habitats, distributed laterally among six geomorphologically distinct reaches, were investigated. Invertebrate abundance increased along the downstream gradient. Richness of Crustacea, Coleoptera, and Ephemeroptera increased whereas Diptera and Plecoptera richness declined along the continuum. At the habitat-scale, richness, dominance, and turnover did not reveal consistent lateral or longitudinal structure, reflecting the individual characteristics within all reaches. At the reach-scale, richness was similar along the entire continuum, whereas turnover (beta diversity) between reaches increased as a function of distance between them. Estimates of richness for lateral components indicated distinct floodplain and tributary communities (i.e., novel assemblages) as well as communities similar to main channel communities (redundancy).
Co-inertia analysis, used to align faunistic and environmental structure along lateral and longitudinal gradients, revealed high taxa-to-environment concordance. Beta diversity was similar across scales because heterogeneity in community assemblages among patches within each habitat was equally as important as heterogeneity within and among reaches. Hot-spots of biodiversity were located in each reach, indicating that aquatic habitats along lateral gradients were major contributors to diversity along the entire river corridor.
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