Influence of Landscape Characteristics on Fish Species Richness Among Lakes of Glacier National Park, Montana

Abstract

Studies suggest that abiotic factors at local and landscape scales partially influence patterns of occurrence of fish species in freshwaters. We examined the occurrence or fishes in relation to landscape characteristics and connectivity of habitat among 16 lakes west of the Continental Divide in Glacier National Park, Montana. Ten native and five nonnative species were observed among lakes, including catostomids, cottids, cyprinids, and salmonids. Estimated species richness (based on rarefaction) varied from 1.00 ± 0.00 to ± 10.22 ± 0.02 (mean ± 95% confidence interval) and estimated native species richness varied from 1.00 ± 0.00 to 7.85 ± 0.02 among lakes. Information-theoretic models indicated that the presence of dispersal barriers had a strong influence on estimated native species richness among lakes. To a lesser extent, lake maximum depth, lake surface area, and distance from study lakes to a common downstream branching point in the hydrographic network influenced estimated native species richness. Nonnative species, specifically lake trout (Salvelinus namaycush), have become widespread throughout the Flathead Drainage, but these data show that the upstream extent of their distribution is limited by the presence of barriers to fish dispersal. Our results indicated that habitat connectivity primarily influences, occurrence, and richness of native species in lakes of Glacier National Park.