CEID members Alexander T. Strauss, Daniel C. Suh, Elizabeth M. Warburton, Michael J. Yabsley, and Christopher A. Cleveland were part of a team of researchers examining infection prevalence and its effects on fitness in Daphnia populations in North American ponds.
Infections peak in spring when Daphnia biomass is highest but vary among ponds and host species. The outbreaks are caused by microsporidian parasites previously found in Europe. The study collected zooplankton samples from seven ponds and monitored them over a period of 1.5 years. Infections were screened, and the prevalence in different species was calculated. Physical and chemical properties of ponds were measured, and the impact on outbreak intensity was investigated. The effects of parasites on host fitness were assessed by comparing fecundity and spore yield. DNA sequencing and analysis were used to identify parasite taxa. They examined the density of Daphnia across seasons and characterized infection dynamics among ponds. Linear regression models were used to determine the influence of environmental factors on disease severity. They aimed to understand disease dynamics, the impact on host reproduction, and the potential specialization of the parasites to specific host species.
They examined the prevalence of microsporidian parasites in different species of
Daphnia in multiple ponds and found that infection prevalence consistently peaked in the
spring. The study confirmed that infection was more likely in the spring and Daphnia ambigua was the most susceptible host overall. The research also revealed that outbreaks of disease were equally likely in ponds dominated by different host species, indicating that variation in host communities did not explain the variation in outbreak size. Infected hosts of each species released large quantities of parasite spores into the environment.
Furthermore, the study found that two parasite taxa, C. obtusa and P. daphniae, were distributed unevenly across host species, with differences in their epidemiological importance for each parasite. This study provides insights into the seasonal and community dynamics of disease in aquatic ecosystems and highlights the complexity of host-parasite associations.
The study, published in Oecologia, can be found here.