Ecology and Decline of a Rare Western Minnow
Title | Ecology and Decline of a Rare Western Minnow PDF eBook |
Author | Todd N. Pearsons |
Publisher | |
Pages | 178 |
Release | 1989 |
Genre | Minnows |
ISBN |
Once historically widespread throughout the Willamette and Umpqua River drainages, the Willamette Oregon chub is now restricted to scattered populations along 15 miles of the Middle Fork of the Willamette River whereas the Umpqua Oregon chub is still widely distributed. The decline in the Willamette drainage was more severe because changes in the physical and biological habitat were more severe when compared to the Umpqua drainage. The Willamette Oregon chub may be more sensitive to environmental degradations than the Umpqua Oregon chub. The difference in sensitivity to degradation is a result of ecological differences between Willamette and Umpqua Oregon chub. Willamette Oregon chub inhabited areas with primarily very little if any current, fed in the water column, and spawned in aquatic vegetation. Umpqua Oregon chub inhabited areas with primarily slow water velocities, fed on benthic prey, and spawned over gravel substrate. Because Willamette Oregon chub inhabit slackwater habitats they may be more sensitive to water velocity increases and exotic species, whereas Umpqua Oregon chub have a habitat refuge in relatively faster water velocity habitats. Willamette Oregon chub larval stages are described and illustrated. The following combination of characters distinguish Willamette Oregon chub larvae from other cyprinid larvae found in the Willamette drainage: 33-37 myomeres, preanal length of 52-61%, and absence of snout pigment. Willamette Oregon chub larvae generally congregated in nearshore areas, in the upper layers of the water column, in shallow water. They fed primarily in the water column, and ate primarily rotifers and cladocerans.
Water-resources Investigations Report
Title | Water-resources Investigations Report PDF eBook |
Author | |
Publisher | |
Pages | 236 |
Release | 1997 |
Genre | Hydrology |
ISBN |
Summary of Information on Aquatic Biota and Their Habitats in the Willamette Basin, Oregon, Through 1995
Title | Summary of Information on Aquatic Biota and Their Habitats in the Willamette Basin, Oregon, Through 1995 PDF eBook |
Author | Bob Altman |
Publisher | |
Pages | 188 |
Release | 1997 |
Genre | Aquatic ecology |
ISBN |
Sport Fishery Abstracts
Title | Sport Fishery Abstracts PDF eBook |
Author | |
Publisher | |
Pages | 238 |
Release | 1991 |
Genre | Fish culture |
ISBN |
Willamette National Forest (N.F), Wolfmann Projects
Title | Willamette National Forest (N.F), Wolfmann Projects PDF eBook |
Author | |
Publisher | |
Pages | 310 |
Release | 1999 |
Genre | |
ISBN |
South Cascades Late Successional Reserve Assessment
Title | South Cascades Late Successional Reserve Assessment PDF eBook |
Author | |
Publisher | |
Pages | 236 |
Release | 1998 |
Genre | Ecological succession |
ISBN |
For a 4(d) Rule for the Conservation of the Northern Spotted Owl on Non-federal Lands, Environmental Alternatives Analysis
Title | For a 4(d) Rule for the Conservation of the Northern Spotted Owl on Non-federal Lands, Environmental Alternatives Analysis PDF eBook |
Author | |
Publisher | |
Pages | 678 |
Release | 1995 |
Genre | |
ISBN |