Sampling and Experimental Procedure
All jars were monitored using a dissecting microscope at a frequency according to their temperature, based on the approximate biological time scale from our pilot (20 and 17.5 oC thrice weekly, 15 and 12.5 oC twice weekly, and 10 oC weekly). Each time, the number of D. magna at each age class (juvenile, adult, adult with eggs) and number of D. magna with visible signs of infection (reddish colouration, no eggs in the brood chamber, gigantism) were recorded. For the 10 oC treatment, a walk-in chamber was used so that monitoring could be done without removing the jars from their temperature. For 12.5, 15 and 17.5 and 20 oC, trays of jars were moved to an insulated cooler box one by one to minimize the amount of time any jar was outside its experimental temperature for monitoring at room temperature.
After the first generations of new-borns were released into the media, experimental D. magna were transferred to jars of fresh medium without sediment at the appropriate temperature to continue observation of infection development without their offspring. Observations continued for 30 days at 20 oC, 35 days at 17.5oC, 44 days at 15 oC, 56 days at 12.5 oC and 81 days at 10 oC, according to the biological time scale determined by the pilot.