Survival, Na+/K+-ATPase
and lipid responses to salinity challenge in fed and starved white pacific
shrimp (Litopenaeus vannamei) postlarvae
E. Palacios, A. Bonilla, D. Luna, I.S. Racotta-2004
Aquaculture, 234(1-4): 497-511
Abstract:
Fed (3-h starved) and 24-h starved 20-day-old
postlarvae (P20) were compared to establish the effect of energy reserves on
survival rate at 0 ppt and osmoregulatory mechanisms at 10 ppt. The activity
of Na+/K+-ATPase was fivefold higher in posterior
gills than anterior gills. The activity of Na+/K+-ATPase
increased by 63% in both anterior and posterior gills in shrimp subjected to
a salinity challenge. No significant increase in carbonic anhydrase activity
was observed in P20 exposed to dilute medium. Starvation did not affect
these osmoregulatory responses, although starved P20 had a significantly
lower survival rate when exposed to dilute medium of 0 ppt. These results
indicate that the lower survival rate from a salinity stress test on starved
P20 cannot be fully explained by impairment of the osmoregulatory
mechanisms. Total lipids (TL) in the hepatopancreas were significantly lower
in starved P20, and triacylglycerides (TG) were slightly but not
significantly lower in P20 exposed to 10 ppt. In gills, triacylglycerides
were significantly higher in P20 exposed to 10 ppt. These results suggest a
mobilization of lipids to satisfy the energy demands of the osmoregulatory
response or an increase in metabolism as part of a general stress response.
(Programa de Acuacultura, Centro de Investigaciones
Biológicas del Noroeste A.P. 128, La Paz, Baja California Sur, 23000,
Mexico, e-mail: epalacio@cibnor.mx)