The Relative Influence of Catchment and Site Variables On Fish and Macroinvertebrate Richness

Landscape and site-scale data analyses aid the interpretation of biological data and thereby help us develop more cost-effective natural resource management strategies.  We evaluated how three classes of environmental variables (landscape, land/cover, and site habitat) influence fish and macroinvertebrate assemblage richness in the Brasilian savanna biome.  The models explained dissimilar amounts of macroinvertebrate taxa and fish species richness: landscape 22% and 20%; land use/cover 36% and 11%; site 28% and 32%; and combined 43% and 47% of the variability in macroinvertebrate and fish richness, respectively.  We conclude that 1) enironmental variables differed in the degree to which they explain assemblage richness, 2) the amounts of variance in assemblage richness explained by landscape and site habitat differed, but relative proportions were similar for both assemblages, although this was not true for the models that combined all three scales of explanatory variables, 3) land use/cover variables explained more variability in macroinvertebrate taxa richness than in fish species richness, and 4) all three classes of environmental variables studied were useful for explaining assemblage richness in Brasilian savanna streams.