Patterns, Processes, And Scale: An Evaluation Of Ecological And Biogeochemical Functions Across An Arctic Stream Network

• Main Author: Parker, Samuel P
• Format: Text
• Language: English
• Published: UVM ScholarWorks 2019
• Subjects: Arctic; Biofilm; Metabolism; Nutrient; Scale; Stream; Ecology and Evolutionary Biology; north slope; Alaska
• Online Access: https://scholarworks.uvm.edu/graddis/1036; https://scholarworks.uvm.edu/context/graddis/article/2036/viewcontent/Parker_uvm_0243D_10807.pdf

Ecosystems are highly variable in space and time. Understanding how spatial and temporal scales influence the patterns and processes occurring across watersheds presents a fundamental challenge to aquatic ecologists. The goal of this research was to elucidate the importance of spatial scale on stream structure and function within the Oksrukuyik Creek, an Arctic watershed located on the North Slope of Alaska (68°36’N, 149°12’W). The studies that comprise this dissertation address issues of scale that affect our ability to assess ecosystem function, such as: methodologies used to scale ecosystem measurements, multiple interacting scales, translation between scales, and scale-dependencies. The first methodological study examined approaches used to evaluate chlorophyll a in ethanol extracts of aquatic biofilms. Quantification of chlorophyll a is essential to the study of aquatic ecosystems, yet differences in methodology may introduce significant errors to its determination that can lead to issues of comparability between studies. A refined analytical procedure for the determination of chlorophyll a was developed under common acidification concentrations at multiple common reaction times. The refined procedure was used to develop a series of predictive equations that could be used to correct and normalize previously evaluated chlorophyll a data. The predictive equations were validated using benthic periphyton samples from northern Alaska and northwestern Vermont, U.S.A. The second study examined interaction and translation between scales by examining how normalization approaches affect measurements of metabolism and nutrient uptake in stream sediment biofilms. The effect of particle size and heterogeneity on rates of biofilm metabolism and nutrient uptake was evaluated in colonized and native sediments normalized using two different scaling approaches. Functional rates were normalized by projected surface area and sediment surface area scaling approaches, which account for the surface area in plan view (looking ...