Effect of copper contamination on zooplankton epidemics

• Published in: Journal of theoretical biology 2019-05, Vol.469, p.61-74
• Main Authors: Banerjee, Swarnendu, Sarkar, Ram Rup, Chattopadhyay, Joydev
• Format: Article
• Language: English
• Subjects: Bistability; Chemical contamination; Daphnia-parasite; Hormesis; Host-resource
• ISSN: 0022-5193; 1095-8541
• DOI: 10.1016/j.jtbi.2019.02.016

•Model linking copper contamination to resource-host-parasite system is formulated.•Deficient or toxic copper may first stabilize and then destabilize host-resource dynamics.•Intermediate copper renders the system disease-free unless spore yield is too high.•Disease may persist in the system when copper enrichment is very low.•Toxic and deficient levels of copper exhibits Allee effect for parasites. Infectious disease and chemical contamination are increasingly becoming vital issues in many ecosystems. However, studies integrating the two are surprisingly rare. Contamination not only affects the inherent host-resource interaction which influences the epidemic process but may also directly affect epidemiological traits via changes in host’s behaviour. The fact that heavy metal such as copper is also an essential trace element for organisms, further increase complexity which make predicting the resultant effect of contamination and disease spread difficult. Motivated by this, we model the effect of copper enrichment on a phytoplankton-zooplankton-fungus system. We show that extremely deficient or toxic copper may have a destabilizing effect on the underlying host-resource dynamics due to increased relative energy fluxes as a result of low host mortality due to fish predation. Further, on incorporating disease into the system, we find that the system can become disease-free for an intermediate range of copper concentration whereas it may persist for very less copper enrichment. Also, we predict that there may exist vulnerable regions of copper concentration near the toxic and deficient levels, where the parasite can invade the system for a comparatively lower spore yield. Overall, our results demonstrate that, the effect of contamination may be fundamental to understanding disease progression in community ecology.