Studies on the Formation and Hatching of Fertilized Eggs of the Rotifer Brachionus plicatilis. V. Resting Egg Formation of the L- and S-type Rotifer Brachionus plicatilis under Different Water Temperature.

Abstract

Rotifer resting eggs can potentially be preserved in a manner similar to Artemia cysts and used as live feed in larval rearing. The potential for producing resting eggs from the most desirable rotifer stocks, the L-type (Japanese stock) and the S-type (Hawaiian stock), at different tempera-tures was investigated. Rotifers from these stocks were reared in 1000l tanks and fed Tetraselmis tetrathele. Salinities were controlled at optimum levels for resting egg production (8 ppt and 32 ppt for L- and S-type, respectively). At culture temperatures ranging from 23.1 to 30.6°C, the L-type rotifers produced more resting eggs at the lowest temperature (23.1°C) and the S-type pro-duced more at a higher temperature (28.2 and 30.6°C). The relationship of resting egg produc-tion to temperature is expressed by a logistic curve. The highest total number of resting eggs was 17.8 million in 8 days at 23°C for L-type rotifers and 101.5 million in 10 days at 28°C for S-type rotifers. The maximum number of resting eggs produced was 3, 400 and 14, 000 per 10, 000 L-type and S-type rotifers respectively. The maximum number of resting eggs produced per 1×108 cells of T. tetrathele was 2, 270 and 11, 100 for the L- and S-types respectively.