Parasites are ecologically ubiquitous and act as key regulators of the dynamics and stability of ecosystems by modifying the physiology and behavior of their host organisms. It is as yet unclear how parasitic relationships will act to moderate or accelerate the ecological impacts of global climate change. We seek to discover how warming may moderate the effects of parasites on the physiology and behavior of their hosts. Utilizing a well-established aquatic host-parasite model system – the ecologically important amphipod Gammarus duebeni and its Acanthocephalan parasite, Polymorphus minutus – full energy budgets were constructed for infected and uninfected hosts across a wide range of temperatures. Analyses of the phototactic and geotactic behavior of the hosts, both infected and uninfected, were also completed across the temperature range.
Results/Conclusions
We found that parasites and warming both independently alter host movement in the water column and host response to light. Moreover, a few degrees of warming has the capacity to alter these critical behaviors to the same extent as infection with arch-behavioral manipulating parasites. These findings indicate an additional mechanism that could be critical to predicting the impacts of warming in many ecosystems. By enhancing host behavioral manipulation and likely the reproductive success of parasites, warming will also likely amplify the effects of parasites on ecological dynamics. These findings highlight the need for holistic knowledge of interaction networks, incorporating both direct and indirect trophic and non-trophic interactions, to predict the independent and combined effects of warming and parasitism on the dynamics and stability of ecosystems.