Influence of individual animal behavior on spatial and temporal variability in nutrient deposition
Albeke, Shannon Edward
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Cross-habitat movement of energy and other materials can spatially link ecosystems, resulting in changes to trophic interactions, ecosystem function and community diversity. Pulses of nutrient inputs, like pulses of productivity, may generate reserves of resources that affect ecological interactions long after the pulse has subsided. However, spatial linkages between ecosystems may be disrupted by temporal discontinuity in transport processes. In order to understand these complex ecological properties and model their effects on the landscape, we must explore the spatial and temporal variation of phenomena, such as variation in nutrient transport (allochthonous inputs). As with seabirds, piscivory by coastal river otters (Lontra canadensis) in nearshore coastal areas provide a pathway for nutrient transport between sea and land, thus extending the resource shed of the terrestrial community into the ocean. Marine-derived carbon (C), nitrogen (N), and phosphorus (P) transported by river otters to terrestrial latrine sites (specific locations along the shoreline) can be several orders of magnitude higher than other nutrient inputs in this system. The following dissertation research represents the synthesis component of an NSF funded project, aimed at developing mechanistic models that will allow the exploration of potential current landscape response to changes in resource availability and otter behavior, as well as forecasting future changes anticipated from climate change. Otters choose latrine sites based on specific environmental characteristics. My results suggest Boundary convexity is the strongest environmental characteristic influencing otter latrine site selection. Additionally, results from the individual-based model (IBM) overwhelmingly indicate otter behavior is almost entirely driven by prey availability. The IBM was able to reproduce observed patterns in nutrient transport, facilitated by the behavioral response of otters to pelagic fish schools and the subsequent creation of social groups. The inclusion of vision, olfaction and memory as viable forms of otter sensing and their quantifiable response to these stimuli provide a strong behavioral foundation for the IBM. The conceptual design of this IBM is applicable to any ecosystem in which variation is caused by behavior, genetic or physiological traits of individuals, and we believe this research provides an excellent working example.