The effect of medium on selected life-history traits in three clones of Lecane inermis (Rotifera) from activated sludge.

We tested the effect of various culture media on life-history traits in three clones of the rotifer Lecane inermis, a potential bulking control agent. Four types of media were tested: a filtrate of activated sludge, mineral water, and each of these media enriched with molasses. The number of live and dead individuals and the number of amictic eggs were counted during the 14-day experiment, and the egg ratio (ER) and mortality rate were calculated. We found that the rotifers were well adapted to the changes in chemical composition of the medium and that the addition of molasses resulted in a significant increase in rotifer abundance. The highest ER was noted after two days, reaching a maximum of 4 eggs per female in treatments with filtrate and molasses-enriched filtrate. The life-history traits varied depending on the clone and the medium, but all of the clones were able to survive and proliferate, even after 14 days of starvation.