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The effects of dietary Docosahexaenocic acid (22:6n-3) and Arachidonic acid (20:4n-6) on growth, survival and stress resistance in black sea bass (Centropristis striata) larvae

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

Abstract: The black sea bass is an important commercial and recreational fishery species on the U.S. Atlantic coast. Decreasing commercial catch and high market value make the black sea bass a promising candidate for aquaculture. Knowledge of the nutritional requirements of the larval stages is fundamental to achieve large scale production of fingerlings or growout farms. Essential fatty acids, especially 22:6n-3 (Docosahexaenoic acid, DHA), 20:5n-3 (Eicosapentaenoic acid, EPA) and 20:4n-6 Arachidonic acid (ArA) are known to have important affects on larval growth and survival in marine finfish. Little or no published information is available on the nutritional requirements of larval black sea bass. The objectives of this study were to determine the effects of dietary DHA to ArA ratio on survival, growth, and stress resistance of black sea bass larvae raised from first feeding to metamorphic stages. Yolksac larvae (day 0 post-hatching = d0ph) were stocked into 15-L aquaria (44 larvae/L) under 34 ppt and 20°C. Larvae were fed enriched rotifers and Artemia nauplii containing two levels of DHA (0 and 10%) in conjunction with three levels of ARA (0, 3 and 6%) in a 2 x 3 factorial design. Five replicate aquaria were assigned to each treatment. Larvae were fed enriched rotifers (Brachionus sp.) from d2ph to d17ph, and Artemia from d18 to d24ph, when all larvae had reached the metamorphic stage. Larvae were sampled weekly to monitor growth as (notochord length (NL), dry weight, wet weight) and survival. On d24ph, a hypersaline (60 ppt) stress test (median survival time at 50% survival) was administered. Rotifers, Artemia and samples of larvae were collected from each treatment to determine fatty acid composition.On d24ph, larvae fed treatment 10:6 (DHA:ARA) showed significantly (P < 0.05) higher survival (16.7%), than larvae fed 0:0 (DHA:ARA) (7.0%). NL and dry weight were also significantly (P < 0.05) greater at the 10:6 (DHA:ARA) treatment level (8.65 mm, 2.14 mg) than in the 0:0 (DHA:ARA) (7.7 mm, 1.65 mg) treatment. During hypersaline challenge, no significant differences (P > 0.05) were shown between larvae fed 10% DHA (25.6 min) and larvae fed 0% DHA (18.2 min.). On d24ph, levels of ArA in black sea bass larvae were higher than levels provided in their diets, while DHA levels were higher in larvae fed 10% DHA than in larvae fed 0% DHA. EPA (20:5n-3) levels were also higher in the larvae fed 10% DHA than in larvae fed 0% DHA. These results suggest conversion of EPA to DHA by black sea bass larvae, but at rates insufficient to produce optimum growth and survival. To summarize, black sea bass larvae fed prey containing 10% DHA showed better growth and survival than those fed 0% DHA. Increased ARA within the range of 0-6% improved growth and survival from the first feeding through metamorphic stages.

Additional Information

Publication
Thesis
A Thesis Submitted to the University of North Carolina Wilmington in Partial Fulfillment Of the Requirements for the Degree of Masters of Science
Language: English
Date: 2009
Keywords
Black sea bass--United States--Atlantic Coast--Growth, Black sea bass--Larvae--United States--Atlantic Coast, Black sea bass--Nutrition--Research, Centropristis--research, Proteins in animal nutrition, Dietary Supplements