Clonal variation in reproductive response to temperature by a potential bulking control agent, Lecane inermis (Rotifera)

摘要

The novel idea of using rotifers Lecane inermis (Rotifera, Monogononta) as a tool to overcomenactivated sludge bulking generates an on-going need to study rotifer biology. The results of biologicalnresearch on rotifers can serve to improve the method so that it can be most effective when applied inntreatment plants. The aim of this study was to test the effect of temperature on four selected rotifernclones originating from different treatment plants. The rate of population development from a singlenindividual (parthenogenetic female) during a 10-day experiment was measured at threentemperatures: 8, 15 and 20 WnC. The temperatures used reflect the annual temperature distribution innthe majority of municipal wastewater treatment plants in the temperate zone. The growth ratencoefficient (r) and doubling time (tD) were calculated for each clone. Under the most favourablenconditions (20 WnC), r values varied between 0.41 and 0.47 d and doubling time between 1.5 and 1.7 d.nAt a temperature of 15 WnC, the doubling time was approximately two times longer (2.5–3.4 d). Thenstrongest intraspecific variations were observed at the lowest temperature of 8 WnC. At thisntemperature, one of the clones almost failed to proliferate, and another exhibited a doubling time ofn7.9 d. The doubling times were a few times greater for the remaining two clones (60 d for Lk1, 33.3 dnfor Lk4). These results could be very useful in predicting the chances that the rotifers would survive inna biological reactor in a wastewater treatment plant at the temperatures used in these reactors.