Abstract Title

The Influence of Sedimentation on Benthic Chlorophyll in Urban Streams

Additional Funding Sources

This research was supported by the City of Pocatello, Idaho.

Abstract

Benthic algae can serve as the base of stream food webs. Because algae depend on stable substrates and sunlight, sedimentation can negatively impact benthic algae growth. Urban streams often experience increased sediment loading, leading to higher rates of sedimentation, suggesting that benthic algae abundance would be negatively correlated with periods of high sedimentation rates. The aim for this research was to investigate the relationship between sedimentation rates and the abundance of benthic algae in Pocatello Creek, an urban stream in southeast Idaho known to transport lots of sediment. We deployed artificial turf grass for ~1 week time periods to quantify sedimentation rates at 12 locations along the stream and measured benthic chlorophyll-a on natural substrate. Canopy cover was also measured at each location as a potential factor influencing benthic algal growth. We hypothesized that there would be an inverse relationship between sedimentation rates and benthic chlorophyll-a concentrations. We did not observe any discernible relationships among benthic chlorophyll-a and sedimentation rates and canopy cover. This could be due to the extreme variability in chlorophyll-a observed over relatively few samples. Collecting more samples might illuminate a trend. This study suggests that other factors such as velocity might have a relationship with benthic algal growth in Pocatello Creek.

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The Influence of Sedimentation on Benthic Chlorophyll in Urban Streams

Benthic algae can serve as the base of stream food webs. Because algae depend on stable substrates and sunlight, sedimentation can negatively impact benthic algae growth. Urban streams often experience increased sediment loading, leading to higher rates of sedimentation, suggesting that benthic algae abundance would be negatively correlated with periods of high sedimentation rates. The aim for this research was to investigate the relationship between sedimentation rates and the abundance of benthic algae in Pocatello Creek, an urban stream in southeast Idaho known to transport lots of sediment. We deployed artificial turf grass for ~1 week time periods to quantify sedimentation rates at 12 locations along the stream and measured benthic chlorophyll-a on natural substrate. Canopy cover was also measured at each location as a potential factor influencing benthic algal growth. We hypothesized that there would be an inverse relationship between sedimentation rates and benthic chlorophyll-a concentrations. We did not observe any discernible relationships among benthic chlorophyll-a and sedimentation rates and canopy cover. This could be due to the extreme variability in chlorophyll-a observed over relatively few samples. Collecting more samples might illuminate a trend. This study suggests that other factors such as velocity might have a relationship with benthic algal growth in Pocatello Creek.