Density of Fish and Salamanders in Relation to Riparian Canopy and Physical Habitat in Streams of the Northwestern United States

Abstract

Relationships between density of fish and salamanders, riparian canopy, and physical habitat were investigated by studying 10 pairs of streams. Among vertebrate taxa, salmonids and sculpins were more abundant in streams without riparian shading than in shaded streams. Abundance of salamanders was not affected by canopy type. Densities of both salamanders and sculpins were correlated with substrate composition, whereas salmonid abundance was not or only weakly so. Salamanders were found only at high-gradient sites with coarse substrates, and sculpins were most abundant at lower-gradient sites with finer-sized sediments. An interaction was observed between the influence of canopy and that of physical setting on density of both invertebrate prey and total vertebrates. Among shaded sites, densities decreased as percent fine sediment increased, but a similar relationship did not exist among open sites. Removal of the riparian vegetation surrounding a stream may therefore mask detrimental effects of fine sediment. These data provide one reason why it has been difficult in the past to generalize about the effects of fine sediment on stream biota.

Movement and Recolonization of Potomac Sculpin in a Virginia Stream

“…Morgan and Ringler (1992) found that summer densities of slimy sculpin did not differ significantly between openand closed-canopy habitat types. In contrast, Hawkins et al (1983) found that freshwater sculpins were more abundant in streams without riparian shading because those streams had higher insect productivity.…”

Fire and amphibians in North America

“…Submerged woody debris and logjams in lakes and streams offer cover for amphibians from predators and are a major structural component of stream ecosystems that influence sediment transport and pool formation (Triska et al, 1982;Harmon et al, 1986). In streams, larval salamanders are often associated with greater habitat complexity from wood and other aquatic cover (Hawkins et al, 1983;Parker, 1991). Large amounts of in-stream woody debris appeared to decrease habitat quality for tailed frogs in coastal British Columbia (Dupuis and Steventon, 1999).…”

“…To protect stream conditions and adjacent riparian habitats, current forestry practices usually recommend or require riparian buffers along headwater streams and certain streams with sensitive fish species (Hawkins et al, 1983;Sedell and Swanson, 1984;Beschta et al, 1987;Bury, 1994;deMaynadier and Hunter, 1995;Diller and Wallace, 1996). In the Oregon Coast Range, riparian buffer strips (typically 20 m or more) may reduce the effects of prescription burning on streams, ponds, and wetlands, and provide amphibian habitat, at least in the short term (Cole et al, 1997).…”

Macroinvertebrates in low-order streams in two fragments of Atlantic Forest in different states of conservation, in the State of São Paulo (Brazil)

“…Wallace et al (1988), who compared brooks with and without riverside vegetation in North Carolina (USA), also observed that invertebrates were more abundant in those without vegetation. Hawkins et al (1983), Angermeier and Karr (1983) e Wallace et al (1988) have proposed that the higher numbers of macroinvertebrates in streams lacking riparian vegetation may be attributed to the increased availability of food due to high levels of primary production by algae.…”