Olivera, V., Simmons, S., Scarpa, J.
Abstract:
Pink shrimp, Penaeus duorarum, are being examined as an
aquaculture species for both the food and bait industry in Florida.
Salinity tolerance of this species is one parameter for culture
conditions that should be known. Therefore, a series of experiments
were performed to determine the minimum lethal salinity level to
postlarvae of different ages.
Pink shrimp postlarvae (PLs) were obtained from a single spawn and
reared together until needed. In Exp. I, PL 11/12 were exposed to
salinities of 28 (control), 25, 20, 15, 10, 5, and 0 ppt in triplicate.
Salinity was adjusted with distilled water, except for the 0 ppt
treatment which was artesian well water (hardness ca 280 mg/L as
CaCO3). Twenty PLs were placed in each 4L container with 3L of
test water that was gently aerated. Water temperature ranged from
25-27 C. In Exp. II, PL 18/19 were exposed to the same salinities
under similar conditions as in Exp. I. After 24 hr, the number of live
and dead shrimp were counted in each container. After determining
the minimum lethal salinity level in Exp. I & II, a third experiment
using PL 22/ 23 was performed to find the exact salinity at which
mortality occurred. The same experimental design was used as in
previous experiments, except the salinity levels tested were 15, 10, 8,
6, 4, 2 and 0 ppt. In all experiments animals were not fed.
In Exp. I with PL 11/12, there were two survival drops: one at 20 ppt
and one at 5 ppt. Virtually all animals died at </= 5 ppt. In Exp II with
PL 18/19, the two drops occurred closer together (10 ppt and 5 ppt).
In Exp. II a few animals survived at 5 ppt (6.7%) and 0 ppt (5%). In
Exp. III, the major drop in survival occurred from 6 to 4 ppt and at
</= 2 ppt there were no survivors. In all treatments in which there
were a majority of live animals there was mortality due to
cannibalism. Further research on growth of pink shrimp at these low
salinities is necessary.
Percentage of live postlarvae after 24 hr exposure at each salinity
level.
Salinity 28 25 20 15 10 5 0
Exp. I 60 70 43 45 55 2 0
Exp. II 77 72 77 83 63 7 5
Salinity 15 10 8 6 4 2 0
Exp. III 72 75 63 60 27 0 0
(Harbor Branch Oceanographic Institution, Inc., 5600 U.S. 1 North,
Ft. Pierce, FL 34946, USA)