Effect of Feed Protein and Carbohydrate Levels on Feed Intake, Growth, and Gonad Production of the Sea Urchin, Lytechinus variegatus

Abstract

In this study, we evaluated protein and carbohydrate levels in cold‐extruded dry diets. Sea urchins (12.6 ± 0.12 SE g wet weight, 29.5 ± 0.11 SE mm diameter) were collected from St. Joseph Bay, Florida (30°N, 85.5°W), and transported to the Texas Agrilife Research Mariculture Laboratory in Port Aransas, Texas. Urchins were held individually in replicated enclosures within a recirculating seawater system (32 ± 2 ppt and 22 ± 2 C). Urchins (n = 16urchins) were fed diets that differed in protein : carbohydrate levels (31:33%, 25:39%, 21:44%, and 17:47% dry weight) for 12‐wk. Survival was 100% in all diet treatments. Urchins fed the 31:33% protein : carbohydrate diet consumed less feed, more dry protein, less dry carbohydrate, less energy, and had lower feed conversion ratios than urchins fed other diets. Urchins fed the 31:33% protein : carbohydrate diet had larger test diameters, total wet weights, production efficiencies, and gonad production efficiencies than urchins in the other diets. Weight gain varied directly and significantly with protein intake. Sufficient energy was available for maximum weight gain as protein was spared. Growth rates and production efficiencies for the urchins in this study were higher than in previous feeding studies with adult Lytechinus variegatus.

Diet-dependent δ13C and δ15N fractionation among sea urchin Lytechinus variegatus tissues: implications for food web models

“…This consisted of an extruded, nutrient-dense diet formulated with vegetal and animal ingredients designed to maximize sea urchin growth (see Hammer et al 2012 for details on composition), which was embedded in agar (10 g of pellets plus 2 g of agar per 100 ml of seawater) to minimize disintegration and cross-contamination across treatments. The formulated diet was prepared when necessary and in the same manner throughout the experiment.…”

δ13C and δ18O signatures from sea urchin skeleton: importance of diet type in metabolic contributions

“…The isotopic composition of sea urchins mirrored dietary signatures, but the further influence of diet quality accounted for further depleted δ 13 C values in fastgrowing individuals fed the formulated diet with high nutrient content (Hammer et al 2012). Enhanced growth rates in urchins fed the formulated and the macroalgae diet (by ~66 and 26%, respectively, compared to the seagrass diet), received higher contributions of metabolic carbon than urchins fed seagrass, particularly in tests.…”

“…1.9 to 2.6 times in WCT and by 2.5 to 2.9 times in tests, compared to individuals fed the seagrass diet. Overall, differences in organic carbon contributions to skeleton formation might be explained by variability in absorption rates (22.7, 46.5, and 58%, respectively, for seagrass, red macroalgae, and the formulated diet) and in the nutritional quality of diets (Hammer et al 2012, Prado et al 2012). …”

“…The formulated diet consisted of an extruded, nutrient-rich diet with vegetal and animal ingredients designed to maximize sea urchin growth (see Hammer et al 2012 for details on composition). The diet was embedded in agar (10 g pellets plus 2 g of agar per 100 ml of seawater) to minimize disintegration and cross-contamination across treatments (see above).…”

“…O signatures in the mineral fraction of L. variegatus tests and whole calcified skeletons (WCT: tests, spines, teeth, and Aristotle's lantern), reared at constant temperature (23°C) from juvenile to adult stages on 2 types of natural and 1 formulated diet specifically developed for L. variegatus (Hammer et al 2012). More specifically, we evaluated the effect of diet on the δ 13 C and δ…”