Stable carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes as natural indicators of live and dry food in Piaractus mesopotamicus (Holmberg, 1887) larval tissue
2008
Jomori, Rosângela Kiyoko | Ducatti, Carlos | Carneiro, Dalton José | Portella, Maria Célia
This study proposed the use of the stable isotope technique to track the type of food utilized by pacu Piaractus mesopotamicus larvae during their development, and to identify the moment when the larvae start using nutrients from the dry diet by retaining its carbon and nitrogen atoms in their body tissues. Five-day-old pacu larvae at the onset of exogenous feeding were fed Artemia nauplii or formulated diet exclusively; nauplii+formulated diet during the entire period; or were weaned from nauplii to a dry diet after 3, 6 or 12 days after the first feeding. δ¹³C and δ¹⁵N values for Artemia nauplii were -15.1[per thousand] and 4.7[per thousand], respectively, and -25.0[per thousand] and 7.4[per thousand] for the dry diet. The initial isotopic composition of the larval tissue was -20.2[per thousand] and 9.5[per thousand] for δ¹³C and δ¹⁵N respectively. Later, at the end of a 42-day feeding period, larvae fed Artemia nauplii alone reached values of -12.7[per thousand] and 7.0[per thousand] for δ¹³C and δ¹⁵N respectively. Larvae that received the formulated diet alone showed values of -22.7[per thousand] for δ¹³C and 9.6[per thousand] for δ¹⁵N. The stable isotope technique was precise, and the time at which the larvae utilized Artemia nauplii, and later dry diet as a food source could be clearly defined.
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