All ETDs from UAB

Advisory Committee Chair

Stephen A Watts

Advisory Committee Members

Louis D'Abramo

James B McClintock

Daniel L Smith

Daniel Warner

Document Type

Dissertation

Date of Award

2015

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Important considerations for the development of sea urchin aquaculture will include understanding nutrition and feed management. These reported investigations contribute to knowledge of dietary protein and carbohydrate requirements in Lytechinus variegatus and feed management strategies. The first evaluation of economic feasibility of sea urchin aquaculture as related to feed costs is presented and the geometric framework (GF) to assess nutrient intake targets is first applied to cultured aquatic organisms to yield recommendations for nutrient balancing in formulated urchin feed. Data- derived models for dietary protein and carbohydrate intake predict increased rates of growth and production among urchins fed diets containing 18% dietary carbohydrate levels as compared to urchins fed diets containing 12% dietary carbohydrate as the level of dietary protein increases up to ca. 30%. The energetic cost of dry matter tissue production suggested more energetic cost (decreased energy efficiency) is required to increase gonad production relative to somatic growth. For both 18 and 12% levels of dietary carbohydrate, cost per gram of wet weight gain was predicted to be maximized at dietary protein levels of 25- 35% or lower, regardless of feed ingredient costs. For urchins fed a standard maintenance feed, increased gonad dry matter production and gonad index were observed among individuals fed at least once per day, regardless of ration size. GF results indicated that adults (120 g) maintained an average dietary protein intake of ca. 0.047- 0.061 g day-1 but did not regulate carbohydrate intake. Juvenile sea urchins demonstrated flexible intake target ranges for dietary protein and carbohydrate. When single diets did not allow the realization of intake targets, urchins maintained weak homeostatic regulation, utilizing ‘fixed proportion’ strategy to maintain a constant ratio of error between protein and carbohydrate intake. Among juveniles provided diets in combination, urchins consumed more of the most balanced (equi- proportioned) diet to regulate protein and carbohydrate within diffuse target ranges. Regardless of whether juveniles were fed single diets or diet combinations, the protein intake target was prioritized over that of carbohydrate.

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