Energy partitioning into
growth, respiration, excretion and exuvia during larval development of the
shrimp Farfantepenaeus paulensis
D. Lemos, V.N. Phan-2001
Aquaculture, 199(1-2): 131-143
Abstract:
Energy channeled into growth (P), metabolism
maintenance (R), excretion (E) and exuvia (Ev)
were quantified in feeding larval stages of Farfantepenaeus paulensis
reared under commercial practices at 26±1°C and 34±1ppt S. Dry weight,
oxygen consumption, ammonia-N excretion and energy content were determined
in protozoeal (PZ I-PZ III) and mysid (M I-M III) stages. In stages PZ III
and M I, a higher weight increment (P) was observed compared to other
larval stages. Energy expended in metabolism (R) increased through
each subsequent stage, showing higher increment in the intervals PZ II-PZ
III (1.7-fold) and PZ III-M I (1.8-fold). Losses by excretion (E) and
exuvia (Ev) presented lower values compared to P
and R. From the total energy assimilated between PZ I and M III,
growth comprised 42% while metabolism 52%. The percentage of assimilated
energy channeled into growth (net growth efficiency or K2)
was ~50% in PZ I and PZ II, reaching the highest value in PZ III (K2=69.9%).
In the following stages, K2 remained between 33.3% and
49.8%. The metabolism (R) and growth (P) ratio showed higher
growth investment in PZ III (R/P=44.9%) compared to other
stages. PZ I and PZ III exhibited higher growth in relation to individual
energy content (P/B>100%), while M II and M III presented
lower results (P/B=12.8-18.6%). Energetics of larval
development indicated a planktonic phase with intense swimming activity and
high metabolic rate, ingestion and growth (PZ I-PZ III). The transition to a
benthic existence was marked by decreased metabolic rate and growth (M I-M
III). These energetic parameters may be used as condition indices for
cultured larvae as they help to explain how hatchery practices may affect
metabolism and growth of the organisms.
(Instituto Oceanográfico, University of São Paulo,
C.P. 66149, São Paulo 05315-937, Brazil, Tel.: +55-11-3818-6548; fax:
+55-11-3032-3092, e-mail: dellemos@usp.br)