Growth survival and resistance to hypersaline stress in larval black sea bass (Centropristis striata) fed varying levels of dietary arachidonic acid (20:4n-6)

UNCW Author/Contributor (non-UNCW co-authors, if there are any, appear on document)
Joseph K. Carrier III (Creator)
Institution
The University of North Carolina Wilmington (UNCW )
Web Site: http://library.uncw.edu/
Advisor
Wade Watanabe

Abstract: Significant advances have been made in controlled breeding and knowledge of environmental requirements for culture of larval black sea bass (Centropristis striata), but there still is relatively little published data on the nutritional requirements of the larval stages, including optimal methods for live prey enrichment with essential fatty acids. The objectives of this study were to determine the arachidonic acid (ARA, 20:4n-6) requirements of black sea bass larvae from the first feeding through metamorphic stages approximately 24 days post-hatching (d24ph). Thirty 15-L aquaria were stocked with d1ph yolksac stage larvae at 100 ind./L. Salinity (34 g/L), temperature (22 °C), photoperiod (18L: 6D), light intensity (1,000 lux), diffused aeration (100 mL/min) and D.O. (> 5 mg/L) were held constant. Background microalgae Nannochloropsis oculata was added daily to maintain 300,000 cells/L. To determine ARA requirements of larvae, live prey organisms, rotifers (Brachionus sp.) and Artemia were enriched with emulsions containing 10% docosahexaenoic acid, DHA (22:6n-3) and five different levels of ARA (0, 6, 8, 10 and 12% total fatty acids, TFA). In a sixth treatment, live prey was enriched with Algamac 2000 (26% DHA, 0% ARA), a commercial fatty acid booster. Rotifers were fed from d2ph at 10 ind./mL, increasing to 23 ind./mL by d18ph. On d18ph Artemia were fed at 0.5 ind./mL, increasing to 3 ind./mL on d22ph. Rotifer feeding ceased on d20ph. Larvae were sampled on d4, d10, d17 and d24ph to monitor survival and growth (NL, wet wt. and dry wt.). On d24ph, hypersaline (55 g/L) stress resistance (ST-50) was evaluated. To measure Na,K,ATP-ase expression, salinity was increased to a sublethal level of 42 g/L and larvae were sampled at 0 h and after 24 h for mRNA analysis by quantitative real-time PCR (qRT-PCR). On d24ph, larval fatty acid profiles reflected dietary levels. Larval NL, wet wt. and dry wt. increased steadily in all treatments during the study, with no significant (P > 0.05) treatment effects. On d24ph, no significant treatment differences in survival (range = 24.3-32.7%) or hypersaline stress (range = 27.1-31.8) resistance were evident. However, larvae fed diets supplemented with ARA (6-12% TFA) demonstrated a significant (P < 0.05) increase in relative mRNA expression of Na+ K+ ATPase after 24 h, whereas larvae fed 0% ARA and Algamac showed no increase. The results indicate that dietary supplementation with ARA at 6-12% promoted the adaptive physiological responses to hypersalinity stress and hypo-osmoregulatory ability in black sea bass larvae.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina at Wilmington in Partial Fulfillment of the Requirement for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Arachidonic acid, Black sea bass--Effect of chemicals on, Black sea bass--Growth
Subjects
Black sea bass -- Effect of chemicals on
Black sea bass -- Growth
Arachidonic acid