Joe M. Fox

Dietary requirement for lysine by juvenile Penaeus vannamei using intact and free amino acid sources

In a preliminary experiment, order-of-limitation of lysine, arginine and methionine was determined for wheat gluten fed to juvenile shrimp. Limitation diets were prepared by singular deletion of the crystalline component of one of the above amino acids from a control diet. Shrimp fed deletion diets had significantly less weight gain than those fed the control diet with the order-of-limitation being lysine ≥ methionine ≥ arginine with lysine being significantly more limiting than arginine. In a subsequent experiment, the dietary requirement for lysine was estimated using juvenile Penaeus vannamei and a 21-day experimental period. Shrimp were fed four different types of diets: (1) 35% crude protein, lysine supplementation via covalently lysine-enriched wheat gluten; (2) 35% crude protein, lysine supplementation via l-lysine HCl; (3) 45% crude protein, lysine supplementation via covalently lysine-enriched wheat gluten; and (4) 45% crude protein, lysine supplementation via l-lysine HCl. Diets containing 35% crude protein contained graded levels of lysine ranging from 3.43 to 6.57% of the protein. Lysine in the diets containing 45% crude protein ranged from 3.33 to 6.67% of the dietary protein. Apparent requirement for lysine was estimated by broken-line regression of instantaneous growth coefficient (IGR) against dietary lysine concentration. No significant difference (P < 0.05) in survival was observed among shrimp fed any of the four different types of diets. Irrespective of means of lysine supplementation, the apparent requirement for lysine by shrimp fed diets containing 45% crude protein was 4.67% of the protein. The apparent requirement for lysine by shrimp fed the diet containing 35% crude protein supplemented with wheat gluten and with l-lysine HCl was 4.49 and 5.19% of the protein, respectively.

Effects of short-and long-term exposure to boat noise on cortisol levels in juvenile fish.

Anthropogenic noise can elicit a significant elevation in plasma cortisol levels in fish (Smith et al. 2004; Wysocki et al. 2006). In response to a stressor, fish attempt to compensate by using a series of biochemical and physiological changes that start with a neuroendocrine response. This response includes the release of cortisol into the circulatory system (Wendelaar Bonga 1997).

Potential effects of long-term exposure to boat noise on the growth, survival, and nutrient retention in juvenile fish.

Fishing and recreational boats are common vessels in coastal waters and contribute to underwater noise, with levels and frequencies related to their size. Texas bays and estuaries are widely traveled by motor-driven recreational and fishing boats and the number of them has increased in the past few years (National Marine Manufacturers Association 2008). Studies have shown that fish react to underwater noise from boats by displaying abnormal behavior (Fuiman et al. 1999; Popper et al. 2004) and reduced growth (Davidson et al. 2009; Wysocki et al. 2007). Fish react to stressful conditions by modulating metabolic rate and repartitioning energy, with the subsequent conversion of stored to available energy at the expense of growth (Wendelaar Bonga 1997).

Dietary Copper Affects Survival, Growth, and Reproduction in the Sea Urchin Lytechinus variegatus

ABSTRACT Copper is an essential micronutrient in the diets of animals. It is a component of many enzymes involved in energy production, participates in immune function, and protects cells from free radicals. However, excessive levels in the diet can be toxic. Small (∼13 g wet weight) Lytechinus variegatus were fed formulated feeds with 12, 36, or 114 mg Cu/kg for 12 wk (levels based on established dietary levels for other marine invertebrates, supplemented as CuSO4·5H2O). Under these experimental conditions, wet weights of individuals fed a 36-mg Cu/kg diet were slightly higher (43.2 ± 1.2 g (SEM); P = 0.069) than those fed a 12mg Cu/kg and 114-mg Cu/kg diet (39.9 ± 1.2 and 40.3 ± 1.7 g wet weight, respectively). Ovary and gut wet weights were significantly lower (P < 0.003) in the 114-mg Cu/kg diet than the 12-mg Cu/kg and 36-mg Cu/kg diets (7.24 ± 0.75 g, 8.11 ± 0.55 g, and 4.99 ± 0.32 g ovary wet weight and 0.97 ± 0.04 g, 1.07 ± 0.06 g, and 0.83 ± 0.04 g gut wet weight for the 12-, 36-, and 114-mg Cu/kg diets, respectively). Mature gamete formation in ovary and testis was inversely correlated with dietary copper level. Acini from the ovaries and testis of urchins in the 36-mg Cu/kg and 114-mg Cu/kg diet treatments had a greater area occupied by nutrient phagocytes than urchins on the 12-mg Cu/kg diet. In diets containing low dietary copper (12 mg Cu/kg), survivorship decreased from 100% to 87%. These data suggest that dietary copper is essential for normal physiological function but can be detrimental for certain physiological processes at high levels. This information will help in the development of formulated feeds for sea urchin aquaculture.

Minerals and Trace Elements in Microalgae

Abstract The term microalgae describes 8 of the 11 common divisions of single cell or colonial plants, the remaining three are macroalgae. The inconspicuous microalgae serve as the primary food resource for higher trophic levels in many ecosystems including lakes, salt marshes, oceans, and submersed vascular plants. This chapter discusses the mineral compositions of various algal groups and the effects of mineral deficiencies and mineral accumulation in the microalgal groups. Minerals constitute the inorganic portion of animal diets. Minerals considered essential for animal life are divided into two general categories based upon level of requirement: macronutrients and micronutrients. This chapter discusses the macronutrients and the micronutrients that support the growth of various microalgae. Also discussed are the “algal blooms”—dense accumulations of microalgae above baseline levels resulting in monotypic aggregates, which may be beneficial in some cases and toxic in some others. Other topics discussed are bioaccumulation and bioremediation. Microalgae can effectively remove many heavy metals from freshwater and marine environments via bioaccumulation in living cells and binding to cell particulates after senescence. Bioremediation is the use of microorganisms (intrinsic or extrinsic) to remove pollutants from naturally occurring waters or anthropogenic waste streams.