Fluctuating temperatures alter environmental pathogen transmission in a Daphnia-pathogen system

Area of Science:

• Ecology
• Environmental Science
• Epidemiology

Background:

• Environmental conditions fluctuate, influencing ecological and epidemiological dynamics.
• Most studies use constant conditions, neglecting the impact of environmental variability.
• Aquatic host-pathogen systems are sensitive to environmental changes.

Purpose of the Study:

• To investigate the effects of temperature variability on the host-pathogen relationship between *Daphnia laevis* and *Metschnikowia bicuspidata*.
• To assess how thermal variability influences host infection, pathogen survival, and host foraging ecology.

Main Methods:

• Experimental manipulation of temperature variability in aquatic zooplankton populations.
• Exposure to fluctuating temperatures (12°C to 28°C) for varying durations daily.
• Assessment of host infection prevalence and intensity, free-living pathogen survival, and host filtering rate.

Main Results:

• Temperature variability significantly affected host filtering rate, a key factor in pathogen transmission.
• Infection prevalence decreased with increased temperature variability, while infection intensity remained unchanged.
• Host survival was reduced by temperature variability, but environmental pathogen survival was not affected.

Conclusions:

• Temperature variability influences zooplankton host demography and host-pathogen interactions.
• Variable temperatures impact pathogen transmission dynamics more than pathogen growth within hosts.
• Zooplankton hosts are more sensitive to temperature variability than the fungal pathogen in this system.