D. Lemos et Vn. Phan, Energy partitioning into growth, respiration, excretion and exuvia during larval development of the shrimp Farfantepenaeus paulensis, AQUACULTURE, 199(1-2), 2001, pp. 131-143
Energy channeled into growth (P), metabolism maintenance (R), excretion (E)
and exuvia (E,) were quantified in feeding larval stages of Farfantepenaeu
s paulensis reared under commercial practices at 26 +/- 1 degreesC and 34 /- 14 parts per thousand S. Dry weight, oxygen consumption, ammonia-N excre
tion and energy content were determined in protozoeal (PZ I-PZ III) and mys
id (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 metabo
lism (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 b
y excretion( E) and exuvia (E,) presented lower values compared to P and R.
From the total energy assimilated between PZ I and M LII, growth comprised
42% while metabolism 52%. The percentage of assimilated energy channeled i
nto growth (net growth efficiency or K-2) was similar to 50% in PZ I and PZ
II, reaching the highest value in PZ III (K-2 = 69.9%). In the following s
tages, K-2 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 ind
ividual energy content( P/B > 100%), while M II and M III presented lower r
esults (P/B = 12.8-18.6%). Energetics of larval development indicated a pla
nktonic phase with intense swimming activity and high metabolic rate, inges
tion and growth (PZ I-PZ III). The transition to a benthic existence was ma
rked by decreased metabolic rate and growth (M I-M III). These energetic pa
rameters may be used as condition indices for cultured larvae as they help
to explain how hatchery practices may affect metabolism and growth of the o
rganisms. (C) 2001 Elsevier Science B.V. All rights reserved.