Structure and size distribution of benthic macroinvertebrate communities along a eutrophication gradient in streams of the Ottawa Valley
McKee, SLD
| HERO ID | 3608169 |
|---|---|
| Year | 1998 |
| Title | Structure and size distribution of benthic macroinvertebrate communities along a eutrophication gradient in streams of the Ottawa Valley |
| Authors | McKee, SLD |
| City | Ottawa, Ontario, Canada |
| Abstract | The taxonomic composition and size structure of benthic macroinvertebrate assemblages from twelve streams were studied in relation to differences in trophic conditions. Orthocladiinae (Diptera: Chironomidae) were numerically dominant at 11 of the 12 sites, however the Hydropsychidae (Trichoptera) attained the highest biomass. Principal component analysis revealed differences in the composition of assemblages among rural and urban sites. Rural sites had higher densities of sensitive taxa such as Ephemeroptera, Chironominae and Simuliidae, while urban sites had higher densities of tolerant taxa such as Oligochaeta. Site scores on the first principal component, explaining the most taxonomic variability between regions, were significantly related to the nutrient differences between the rural and urban streams. The mean annual spectrum for the entire assemblage followed a unimodal distribution peaking at the 8 $\mu$g (dry mass) size class. Polynomial regression models fitted to the abundance per size class for the entire assemblage revealed a weak positive relationship with total phosphorus (TP). Subsequent analyses on the mean size spectra of seven dominant taxa revealed that the Oligochaeta and Hydroptilidae have significantly higher densities in the urban sites, which contain high TP, while the Ephemeroptera and Chironominae have significantly lower densities in these sites. The three other dominant taxa, including the Hydropsychidae, Tanypodinae and Orthocladiinae showed less obvious differences in densities per size class between regions. These results demonstrate that although the size spectra of the entire community may not be greatly influenced by differences in stream eutrophication, the spectra of certain key taxa do show responses of a higher magnitude. This discrepancy in detecting responses suggests that the size distribution of entire benthic assemblages is resilient to differences in stream productivity, despite significant changes in the taxonomic composition. |
| Url | https://www.ruor.uottawa.ca/handle/10393/4217 |
| Is Certified Translation | No |
| Dupe Override | No |
| University Name | University of Ottawa |
| Paper Level | Master's Thesis |
| Is Public | Yes |
| Language Text | English |