Date of Award

Fall 2018

Document Type

Open Access Dissertation

Department

Marine Science

First Advisor

Carol L. Boggs

Abstract

Mis-matches in climate-mediated shifting rates cause the ranges of some species to become decoupled from their historic ecosystem, leading to the colonization of ecosystems they have not previously inhabited. When this occurs, the shifting species may experience suboptimal conditions which challenge its ability to persist and expand into the novel ecosystem. However, within the colonized ecosystem, shifting species may encounter artificial habitat analogues: artificial habitats that more closely resemble the species’ historic ecosystem than the surrounding habitat and which mitigate some of the negative impacts experienced elsewhere in the novel ecosystem. Despite their importance to the ecology, life history, and continued expansion of range shifting species, habitat effects within novel ecosystems are poorly understood. This dissertation explores habitat effects within the context of the range expansion of the mangrove tree crab Aratus pisonii. We show that the artificial structure of boat docks acts as a habitat analogue to the historic mangrove ecosystem of this crab and thus alleviates many negative impacts it experiences in the colonized salt marsh ecosystem. Docks mitigate the alteration of ecologically relevant behaviors and, by providing improved thermal and dietary conditions, negative ecological and life history impacts A. pisonii otherwise experiences as it colonizes the salt marsh. Through a mechanistic exploration of reproductive potential and fitness, we also show that while the mangrove provides the best reproductive environment for A. pisonii, diet-driven differences in maternal reproductive investment allow the dock habitat to increase reproductive potential and fitness over the

surrounding salt marsh. Further, while they fail to fully grant refuge from hurricane disturbances, docks provide a thermal refuge during winter die-backs allowing A. pisonii to expand more quickly and further into the salt marsh than would otherwise be possible. Ultimately, this dissertation emphasizes the impact of habitat effects in altering the ecology, life history, and expansion of range shifting species while highlighting the ability of artificial structures to act as habitat analogues and mitigate negative impacts that may otherwise be encountered in colonized ecosystems.

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