Salinity Adaptability of Five Different Strains of the Rotifer Brachionus plicatilis.

In order to know the physiological adaptation of the rotifer, salinity adaptability of five strains of the rotifer Brachionus plicatilis, namely, YL, YS, MS, JS, and IL was observed under different salinities of 5, 15, 25, 35, and 45%. The number of offspring was used as an indicator of rotifer production rate and was observed on cultures acclimated to each salinity for 0, 15, 35, 55, and 75 days. The index of adaptation was deduced from the slope of the linear regression equation obtained by plotting data on the number of offspring vs. acclimation periods. The YL and YS strains showed high adaptability to all salinities, showing a highly euryhaline characteristic. MS exhibited high tolerance to low salinity with high production rate. However, at high salinities, the tolerance was low with low production rate inspite of acclimation for 75 days. JS and IL were both more euryhaline than MS, but not as euryhaline as YL and YS.