Factors affecting low temperature
preservation of the marine rotifer Brachionus rotundiformis Tschugunoff
M. Assavaaree, A. Hagiwara, E. Lubzens-2001
Hydrobiologia, 446/447: 355-361
Abstract:
Experiments were performed to determine suitable conditions for low
temperature preservation of small S (Fukuoka) and ultra-small SS (Thai)
strains of B. rotundiformis. For this, single rotifers (an adult bearing one
egg or a 4-h neonate) were incubated for 10 days in 1 ml seawater (22 ppt
salinity). The highest survival was achieved at 10 and 12 °C for S-strain
and 12 °C for SS-strain. The effect of salinity, change of culture medium
and feeding regime were further tested on rotifers (300 ind. ml^−1)
cultured in vials containing 10 ml seawater and microalgae at 12 °C.
Survival of S-strain was highest (55.5±0.8%) at 35 ppt, while SS-strain
survived best (43.1±2.6%) at 17 ppt. Survival was suppressed by changing
the culture medium every 4 days. Feeding rotifers every 2 days yielded
better survival (66.2±6.6%: S-strains, cultured at 35 ppt and 81.8±5.2%,
SS-strains cultured at 17 ppt) than feeding them only at the beginning of
the experiment or at 4-day intervals. An acclimation at 20 °C for 24 h
before transferring them from their usual culture temperature (28 °C) to 12
°C resulted in higher survival of SS-strain. For S-strain, however, no
significant improvement resulted from acclimation. SS-strain was more
susceptible to lower temperature and higher salinity than S-strain.
(Graduate School of Marine Science and Engineering,
Nagasaki University, Bunkyo-machi 1-14, Nagasaki 852-8131, Japan (Address in
Thailand: National Institute of Coastal Aquaculture, Kao Saen Soi 1, Muang
District, Songkhla 90000, Thailand).