All ETDs from UAB

Advisory Committee Chair

Stephen A Watts

Advisory Committee Members

Ken R Marion

Mickie L Powell

Document Type

Thesis

Date of Award

2014

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

Sea urchins are an important economic resource for many international fisheries and are an important animal model in developmental biology. Currently, health of cultured sea urchins is evaluated by behavior or through invasive examination of internal tissues. Destructive sampling is not conducive to longitudinal studies and a non-invasive method of evaluating sea urchin health would have practical application. Evaluation of the egesta could provide a valuable predictor of physiological well-being. The size and morphology of fecal pellets produced by the sea urchin Lytechinus variegatus under a variety of environmental and nutritional conditions were characterized in terms of 2-dimensional area, length, width, and circularity. Urchins receiving a formulated diet produced highly circular pellets surrounded by mucus, whereas urchins receiving natural and practical diets produced a wide variety of irregularly shaped pellets. Additionally, larger urchins produced pellets that were larger in size, but did not differ in circularity from smaller adult or juvenile urchins. Urchins exposed to abiotic and biotic conditions, including temperature, salinity, light exposure, and LPS injections, produced pellets that did not vary in size or circularity between treatments, though urchins exposed to injections of bacterial LPS or a decreased daily ration (caloric restriction) produced a higher percentage of pellets that had qualitative abnormalities. Urchins maintained on various feeding regimes produced pellets that had significant decreases in circularity when proffered a restricted ration or a feed high in copper, and also produced larger pellets when fed a diet high in lipid. Variation within an individual urchin was significantly decreased when certain sublethal stressors were present, which included elevated water temperature, chronic exposure to LPS, and high dietary copper levels. Transmission electron microscopy of sea urchin feces indicated that pellets contain numerous bacteria, many of which are active in the processes of cell division. These data suggest that bacteria have an integral role in the digestive processes. Further utilization of feces analysis may provide not only a better understanding of sea urchin digestive processes, but also provide a practical method with which to evaluate overall urchin health and well-being.

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