Thesis (Ph.D.)--University of Delaware, 2006. / Principal faculty advisor: Charles E. Epifanio, College of Marine and Earth Studies. Includes bibliographical references.

Thesis (M.S.)--Georgia Southern University, 2008. / "A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." Directed by Sophie B. George. ETD. INDEX WORDS: Fiddler crabs, Population density, Salt marsh, Survey techniques Includes bibliographical references (p. 28-30) and appendices.

Thesis (M.S.)--Georgia Southern University, 2006. / "A dissertation submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science" ETD. Includes bibliographical references (p. 31-35)

Thesis (M.A.)--Boston University. Note: Page 24 is missing. / Many animals, invertebrates as well as vertebrates, have demonstrated an ability to somehow sense ionizing irradiation. This recognition is often apparent by a behavioral response which can be correlated with the x-ray stimulus in some way. The fiddler crab, Uca pugilator, was found to exhibit a behavioral response to ionizing irradiation. When the x-ray machine was turned off, the animal would respond instantaneously by a marked hesitation in its general movement after which it would resume its normal activity. This response suggests the animal's ability to somehow be aware of irradiation. Previous work in this area suggested that the photoreceptors were the primary site of stimulation. The fiddler crab's photoreceptors, located at the ends of protruding eye-stalks, are particularly easily excised. When the eye stalks were rer1oved, the response to x-rays was no longer evident. A parallel series of experiments were done with ltght as the stimulus. With intact eyestalks, the animal showed the same off response, and with the eyestalk removed, the subject exhibited no such response. The possibility of a direct stimulation of nervous structures as well as that of an indirect activation by the x-ray evoked release of bioactive substances is discussed. After considering the sinus gland, which was also removed along with the photoreceptors, as a possible site of x-ray reception, a strong implication that the photoreceptors are the primary locus of x-ray sensitivity in the fiddler crab was stated. The marked dose rate dependency of the animal's response to x-rays was noted, and a possible explanation was suggested.

Thesis (Ph. D.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains xv, 239 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references.

No description available.

Thesis (M. Phil.)--University of Hong Kong, 1991.

published_or_final_version / Zoology / Master / Master of Philosophy

Research in salt marshes dominated by the grass Sporobolus alterniflorus indicates that plant characteristics affect fiddler crab burrowing and in turn, crab activity can enhance primary productivity by increasing soil oxygen and nutrient cycling. Crab-plant interactions are less understood in microtidal Gulf Coast marshes compared to Atlantic Coast tidal marshes. It is unknown how structure of the dominant Gulf Coast vegetation zones (salt marsh, brackish marsh, fresh marsh and salt pannes) affects density of crab burrows and how burrows may influence primary productivity. I hypothesized that fiddler crabs would be most abundant in marsh zones with intermediate substrate hardness and vegetation density (Goldilocks Hypothesis). A seasonal habitat preference study was conducted during 2016-2017 in tidal marshes at Grand Bay National Estuarine Research Reserve in coastal Mississippi using burrow density as a proxy for crab abundance. Plant above- and below-ground biomass, burrow proximity to vegetation, and soil hardness were also surveyed as potential drivers of fiddler crab populations. The results indicated that fiddler crabs burrow in all four zones, but to varying degrees, and that burrow density was highest during autumn. The fresh marsh had the highest average density of burrows, as well as vegetation and soil parameters most representative of intermediate habitat, thereby supporting the “Goldilocks Hypothesis”. The brackish marsh also proved to be important fiddler crab habitat. Preferential fiddler crab usage of habitat upslope of salt marsh, e.g., fresh and brackish marsh, in Gulf Coast sites suggests that they may avoid immediate impacts of rising sea levels and possibly even migrate to higher ground if needed.

No description available.