Record Details
Lotic macroinvertebrate distribution patterns in northeastern Oregon
ScholarsArchive at Oregon State University
| Field | Value |
|---|---|
| Title | Lotic macroinvertebrate distribution patterns in northeastern Oregon |
| Names |
Gerth, William J.
(creator) Li, Judith L. (advisor) |
| Date Issued | 2004-03-12 (iso8601) |
| Note | Graduation date: 2004 |
| Abstract | This study was an investigation of lotic macroinvertebrate distribution in northeastern Oregon at two different spatial and biological scales. Examination of assemblages at a limited spatial scale revealed relationships with natural and disturbance gradients and led to questions about distribution of a population at broader spatial scales. In a 16 kilometer section of the North Fork John Day River, I examined the relationship of invertebrate assemblages to habitat and fine sediment deposition. This river section was subjected to sediment inputs resulting from several years of floodplain mine-tailing leveling, and erosion and tributary channel scouring following a forest fire. Invertebrate assemblages differed between habitat types. The proportion of sediment tolerant invertebrates, especially oligochaete worms, increased with higher amounts of deposited fine sediment, but total invertebrate abundance was not related to deposited sediment. The response of sediment tolerant invertebrates appeared to reflect cumulative impacts from multiple input points and downstream transport of sediment and cumulative and/or increasing impacts over the two years of sampling. In studying assemblages in the North Fork, I noticed an unusual abundance of the caddisfly, Lopidostoma pluviale (Milne). In a more spatially extensive examination of a population, I investigated distribution of this caddisfly in the Blue Mountain region of northeastern Oregon. L. pluviale was more common and/or abundant further downstream than would be expected for a shredding feeder based on the River Continuum Concept (Vannote, et al., 1980). Through gut content analyses, I demonstrated that this species is much more of a generalist feeder than its designation as a shredder would imply. Consequently, its distribution is not limited to headwaters where allochthonous food resources are abundant. I hypothesize that non-food environmental factors may be more important in determining the distribution of this species. Results of this research indicate that assemblage studies can reveal interesting relationships with environmental conditions. In addition, paying attention to unusual distributions of taxa in assemblage studies can lead to further studies that can improve our understanding of the biology and ecology of species. |
| Genre | Thesis/Dissertation |
| Topic | Freshwater invertebrates -- Oregon -- John Day River |
| Identifier | http://hdl.handle.net/1957/30420 |
