Ontogenetic variation in
metabolism, biochemical composition and energy content during the early life
stages of Farfantepenaeus paulensis (Crustacea: Decapoda: Penaeidae)
D.
Lemos, V. N. Phan-2001
Marine Biology, 138(5) : 985-997
Abstract:
Dry weight (DW), oxygen consumption, ammonia-N
excretion, proximate biochemical composition (total protein, carbohydrate,
lipid, water and ash), and energy content (estimated from biochemical
composition and by wet combustion) were determined in early developmental
stages of cultured Farfantepenaeus paulensis. Pooled samples from
embryonic, larval and postlarval stages (at 26 ± 1 °C and 34 ± 1‰) were
used for measurements. The study focused on physiological and biochemical
processes during transitional periods of ontogeny, such as hatching,
lecithotrophic and planktotrophic stages, metamorphosis, and the attainment
of a benthic existence in postlarva. DW showed higher increment between
protozoea I (PZ I) and mysis I (M I) than in the next mysid and postlarval
stages. Individual rates of oxygen consumption and ammonia-N excretion
increased, while weight-specific rates presented significant reduction
throughout development. Higher weight-specific oxygen consumption was
registered in nauplius III (N III) and PZ I, following a decrease in
subsequent stages. Postlarval stages PL V-VI and PL X-XII exhibited the
lowest values among the stages studied. Weight-specific excretion was high
in N III and protozoeal stages, with maximum values in PZ II, while the
following stages were marked by lower rates. O:N ratios indicated higher
protein catabolism in the stages between egg and M I and a shift to more
lipid utilization close to metamorphosis. Water content was higher in the
protozoeal stages and decreased afterwards. Higher percentages of protein,
lipid and carbohydrate (%DW) were observed in egg and nauplius stages.
Protein and lipid decreased from the egg through the naupliar and protozoeal
stages, rising again in mysis stages. Lipid content (%DW) decreased in PL
V-VI and PL X-XII. Lipid:protein ratios showed an increase of the importance
of lipid between PZ III and M II. Carbohydrates represented a minor fraction
of body composition, and ash percentages increased from egg to a maximum in
PZ II, decreasing in subsequent stages. Energy content determined by wet
combustion or calculated by energy equivalents presented the same trend
throughout development, varying similarly to protein. Protein was the main
energy contributor to body energy in all stages, while the importance of
lipid was higher in egg and early naupliar stages. Trends observed in
metabolic rates and body composition may be associated to morphological and
behavioral changes during the early stages of penaeid development, such as
the transition from herbivory to omnivory, and the adoption of a benthic
existence. Different ontogenetic energy strategies contribute to succeed
through such diverse type of development.
(Instituto Oceanográfico, University of São Paulo, C.P. 66149, São
Paulo 05315-937, Brazil, fax +55-11-3032 3092, e-mail: dellemos@usp.br)