Screening methods for improving rotifer culture quality

We studied whether the selection of rotifer B. plicatilis strain (Japanese. Russian or Australian), Lis well as the addition of gamma-aminobutyric acid (GABA) to the culture water. are useful in stabilising rotifer cultures. We examined the effect of a combination of the following, stressors: Unionized ammonia (2.4 mg l(-1)), contamination by protozoa Euplotes sp. (10 cells ml(-1)) and addition of methyl Cellulose to increase the culture water viscosity at 15 cp. Rotifer reproductive tests and enzyme activity measurements (glucosidase) were conducted to determine the effect of the treatments. All tests were conducted at 25 degrees C and rotifers were fed Nannochloropsis oculata at 7 x 10(6) cells ml(-1). The combined effects of the stressors caused a significant decrease in lifespan, fecundity and glucosidase activity. The effect of the stressors on reproductive characteristics and glucosidase activity could be neutralized if rotifers were treated with GABA.