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Abstract
The goal of this dissertation is to investigate the impacts of benthic fauna across multiple scales, with particular emphasis on the importance of benthic fauna for two major marine interfaces: the sediment-water interface, and the interface between the terrestrial and marine environments. Combined model-laboratory studies are used to investigate benthic faunal impacts and variability at the scale of individual plots in order to document the importance of burrow patchiness. This work additionally expands on the scale-based nature of patchiness with explicit consideration of sediment reactivity and a discussion on the implications for sampling regimes in different environments. Laboratory-modeling studies are used to describe the importance of individual organisms variability, particularly in two important behaviors: burrowing depth and burrow irrigation intensity. Laboratory microcosms are used to parameterize a reaction network describing nitrogen cycling and early diagenesis in arenicolid-inhabited sediments. Burrowing depth, irrigation intensity, and environmental conditions are manipulated within the model to gain a clearer understanding of the importance of organism behavior for nitrogen cycling. Large-scale analysis is used to consider the system-wide impacts of benthic fauna. Denitrification estimates for whole estuaries are obtained from the literature and combined with databases containing nutrient availability and benthic community status for those same estuaries. This dataset is used to investigate the relationships between benthic community status (diversity and abundance) and system scale denitrification. Literature data on the individual effects of benthic fauna are then combined with the large-scale database to create a model able to predict estuarine denitrification, using nutrient availability and benthic organism abundance as the fundamental controls of denitrification.