Acclimation of
litopenaeus vannamei postlarvae to low salinity: influence of age, salinity
endpoint, and rate of salinity reduction
W.J. McGraw, D.A. Davis, D. Teichert-Coddington, D.B.
Rouse-2002
Journal of the World Aquaculture Society, 33(1):
78-84
Abstract:
Inland culture of Litopenaeus vannamei in low
salinity well waters is currently conducted on a small scale in a few areas
in the U.S. To successfully rear shrimp in low salinity water, postlarvae
(PL) must be transferred from high-salinity larval rearing systems to
low-salinity growout conditions. To determine effective transfer methods, a
series of experiments were conducted under controlled conditions to evaluate
the influence of PL age, rate of acclimation, and salinity endpoint on 48 h
survival of shrimp. Three age classes of L. vannamei PL (10, 15, and 20-d)
were acclimated from a salinity of 23 ppt to treatment endpoint salinities
of 0, 1, 2, 4, 8, and 12 ppt. Survival of PL10 acclimated to 0,
1, or 2 ppt salinity was significantly lower than survival of PL acclimated
to salinities of 4, 8, and 12 ppt. Survival of PL15 and PL20
shrimp was only reduced for the 0 ppt salinity treatment, thus indicating a
clear effect of age on salinity tolerance. The same age classes of PL were
acclimated from 23 ppt to final salinity endpoints of 1 or 4 ppt at three
different rates of salinity reduction: low, 19%/h; medium, 25%/h; and high,
47%/h. Survival was not significantly influenced by the acclimation rates
for any of the three PL age classes. As in the fixed rate experiments,
survival of the 10-d-old PL was significantly lower for shrimp acclimated to
the 1 ppt endpoint compared to the 4 ppt endpoint. Under the reported
conditions, age appears to influence PL tolerance to a salinity endpoint. A
10-d-old PL can be acclimated to 4 ppt with good survival, whereas 15- and
20-d-old PL can be acclimated to a salinity of 1 ppt with good survivals.
(Department of Fisheries and Allied Aquacultures,
Auburn University, Alabama 36849-5419, USA)