Periphyton are an important group of primary producers in stream ecosystems and are commonly used as indicators of water quality and ecosystem status. Periphyton biomass accumulation in streams is influenced by a number of factors, including nutrient supply, shading by riparian vegetation, substrate properties, and hydrological conditions. Urban land use potentially influences all of these factors in ways that may promote or constrain periphyton growth. Such influences may be further altered by efforts to restore urban streams within parks and residential settings. To test this, I compared patterns of stream periphyton biomass among rural (forested), urban, and restored urban streams within and around Umeå. I found that periphyton biomass varied up to 50-fold among sites but did not differ significantly among stream classes (i.e., rural vs. urban vs. urban restored). Periphyton biomass did tend to increase among sites with greater nutrient concentrations and warmer temperature. Yet, these patterns were influenced by substrate conditions within and among streams, with significantly greater biomass observed on larger cobbles when compared to sand. Results indicate that sedimentation in the studied urban streams (and likely in streams in general) may restrict algal growth, even if other conditions are otherwise favourable. Conversely, urban restoration involving the placement of course substrate on the stream bottom may enhance algal growth locally, particularly where light and nutrients are both elevated. My findings illustrate that periphyton biomass depends on a multi-scale framework of factors that should be considered when managing streams, especially in urban areas where streams are often influenced by both local and catchment-scale stressors.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:umu-225601 |
| Date | January 2024 |
| Creators | Långberg, Anton |
| Publisher | Umeå universitet, Institutionen för ekologi, miljö och geovetenskap |
| Source Sets | DiVA Archive at Upsalla University |
| Language | English |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
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