M. Albentosa et al., DETERMINATION OF OPTIMAL THERMAL CONDITIONS FOR GROWTH OF CLAM (VENERUPIS-PULLASTRA) SEED, Aquaculture, 126(3-4), 1994, pp. 315-328
The energy budget of Venerupis pullastra clam seed (3 mm) fed the micr
oalga, Isochrysis galbana T-ISO, was calculated after acclimation at 1
0, 15, 20 and 25 degrees C. Physiological measurements included ingest
ion rate, absorption efficiency, oxygen consumption and ammonia excret
ion. The effect of temperature on these rates was described. Ingestion
rate was directly related to temperature up to a maximum at 20 degree
s C. Further temperature increase caused a slight decrease in ingestio
n. Absorption efficiency was not significantly influenced by the tempe
rature, although maximum mean values were also found at 20 degrees C.
Both respiration and ammonia excretion rates were directly related to
temperature over the whole experimental range, reaching their maxima a
t 25 degrees C. For all the physiological rates measured the higher sl
opes in the rate/temperature lines occurred in the medium range of tem
peratures (15-20 degrees C). The scope for growth (SFG) was positive a
t all temperatures and maximum at 20 degrees C, chiefly as a consequen
ce of the enhanced ingestion rate which offset the concomitant elevati
on in metabolic rates. Both gross and net growth efficiencies are also
expected to be maximum at 20 degrees C, which is, therefore, the ther
mal optimum for this species under the experimental conditions applied
in our study. An acclimation strategy for this low-shore species with
in the range of thermal variation in its natural environment (10-20 de
grees C), maximizing SFG at high temperatures by enhancing ingestion r
ate, despite increased metabolic costs, is proposed.