ABSTRACT:

Humans have been creating artificial aquatic ecosystems for thousands of years. Some of these aquatic ecosystems are highly managed, especially in the semi-arid, Intermountain West. Here, humans have constructed extensive conveyance systems to support agriculture, to mitigate flooding, and to discharge stormwater. Despite their regional prevalence, the ecological structure and functioning of these conveyance systems remains largely unknown. To address this gap, I addressed the following questions: 1) How do water quality, freshwater invertebrate assemblages, and leaf decomposition compare between the Northwest Field Canal and its water source, an urbanized reach of the Logan River? 2) How do these measures change longitudinally in both waterways as they traverse Logan City? and 3) Which of the physical, chemical, and biological factors I measured most strongly influence leaf decomposition in these waterways? I collected water quality and freshwater invertebrate samples, and I measured leaf decomposition at twenty sites along the Logan River and an urban canal. I used Spearman’s correlation coefficients to evaluate the associations between physical, chemical, and biological factors and leaf decomposition. Water quality was similar between waterways, except for the most downstream site of the Logan River, which had elevated concentrations of nutrients and metals, and lower richness and abundance of invertebrates. Leaf decomposition occurred faster in the canal, and the canal had higher biomass of shredders compared to the Logan River. Facultative shredders were associated with the decay rate in the canal, suggesting that these shredders are associated with leaf decomposition. Leaf decomposition was faster at downstream sites in both waterways relative to the upstream sites, due to an abundance of facultative shredders in the canal and elevated nutrients at the most downstream site in the Logan River. Water velocity was associated with leaf decomposition in both waterways, and total phosphorus was positively associated with biomass of shredders and leaf decomposition, the latter of which is likely due to enhanced microbial activity.

ABSTRACT:

Code and data repository for the Environmental Research Letters article "Worldviews more than experience predict Californians’ support for wildfire risk mitigation policies. See Readme.md below for downloading and installation instructions and Readme.html in project file directory for more details.