High density culture of the freshwater rotifer, Brachionus calyciflorus

H. Gi Park, K. Woo Lee, S. Hwoan Cho, H. Sun Kim, M.-M. Jung, H.-S. Kim-2001

Hydrobiologia, 446/447: 369-374
Abstract:
The freshwater rotifer, Brachionus calyciflorus is one of the live food organisms used for the mass production of larval fish. In this study possibility of obtaining high density cultures of the freshwater rotifer B. calyciflorus were investigated. The two culture systems used differed in their air and dissolved oxygen supplies using three temperatures in each case: 24, 28 and 32 °C. Rotifers were batch-cultured using 5 l-vessels and fed with the freshwater Chlorella. The growth rate of rotifers significantly increased with an increase in temperature. The maximum density of the rotifers with air-supply at 24 °C, 6500 ind. ml^−1, was significantly lower than those cultured at 28 and 32 °C, i.e. 8600 and 8100 ind. ml^−1, respectively. Dissolved oxygen levels decreased with time and ranged from 0.8 to 1.4 mg l^−1 when the density of freshwater rotifer was the highest at each temperature. The highest density (19 200 ind. ml^−1) of freshwater rotifer was obtained in cultures with a supply of oxygen at 28 °C. Densities of 13 500 and 17 200 ind. ml^−1 were found at 24 and 32 °C, respectively. Levels of NH_3-N increased with time and a dramatic increase of NH_3-N was observed at high temperatures. Levels of NH_3-N at 24, 28 and 32 °C were 13.2, 18.5 and 24.5 mg l^−1, respectively. These levels coincided with the highest rotifer density at each of the three temperatures. When rotifers were cultured with an oxygen-supply and pH was adjusted to 7, the maximum density of rotifer reached 33 500 ind. ml^−1 at 32 °C . These results suggested that high density culture of freshwater rotifer, B. calyciflorus could be achieved under optimal conditions with DO value of exceeding 5 mg l^−1 and NH_3-N values of lower than 12.0 mg l^−1.

(Faculty of Marine Bioscience & Technology, Kangnung University, Kangnung 210-702, Korea, e-mail of M.-M. Jung:
jungminmin@nfrda.re.kr, jungminmin@hanmail.net)

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