Low-temperature preservation
(at 4 °C) of marine rotifer Brachionus
M.
Assavaaree, A. Hagiwara, K. Ide, K. Maruyama, E. Lubzens-2001
Aquaculture Research, 32 (1): 29-39
Abstract:
Mass production of rotifers is essential as live food
during the larval rearing season, but a major problem of rotifer culture is
unpredictable culture collapse. If mass-produced rotifers could be kept
alive at low temperature for an extended period of time, they could be
supplied as live food to cultured marine fish larvae without interruption.
Four experiments were performed to test this possibility in six strains of Brachionus
plicatilis O. F. Müller and eight strains of Brachionus
rotundiformis Tschugunoff. The results showed that: (1) B.
rotundiformis strains were less tolerant to 4 °C than B.
plicatilis strains. Among the B. rotundiformis strains, the
strains known as SS type were the most susceptible and showed the lowest
survival. (2) Exchange of culture media during the incubation at 4 °C
in B. plicatilis and B. rotundiformis resulted in higher
survival than not changing the culture media, but there were no differences
in the regression slope with or without changing the culture media. (3)
Acclimation at 15 °C for 96 h for B. plicatilis and B.
rotundiformis before transfer to 4 °C resulted in higher survival
rates than acclimation at 10 °C. (4) The combination of frequent
exchange of culture media and acclimation significantly improved the
survival of B. plicatilis and B. rotundiformis compared with
controls that were maintained at 4 °C without exchange of the culture
media. Large-scale trials using B. plicatilis (Kamiura strain)
cultured in 30-L tanks were conducted in a hatchery at a density of
2000–20 000 individuals mL-1. Rotifers were transferred
directly from 25 °C to 4 °C. About 50% of the rotifers at 20 000
individuals mL-1 survived after 14 days at 4 °C.
These preserved rotifers could be cultured at 20 °C, recovering within
4 days.
(Faculty of Fisheries, Nagasaki University, 1–14 Bunkyo-machi, Nagasaki
852-8521, Japan)