Authors
A T Stewart1; J Cable1; J A Jackson2; P Hablützel3; 1 Cardiff Univerisity; 2 The University of Salford; 3 University Leuven Discussion
Climate change is characterised not just by increased temperatures, but variable and unpredictable temperatures. Variability, driven by events such as El Niño, have aided in the spread of pathogens like chytrid fungus Batrachochytrium dendrobatidis; but little is known about how contraction/amplification of variability (shorter or longer seasons) might affect infectious disease. This study utilises the Three-spined Stickleback (Gasterosteus aculeatus) and two of its parasites, Gyrodactylus gasterostei and Saprolegnia parasitica, to model the effects of winter length variation on parasite growth and host immunity. Our aim is to better understand how these two parasite taxa, which are of particular commercial importance in the aquaculture industry, might respond to changes in winter length variability. During the course of this experiment we uncover a tale of two parasites that respond differently to climate variability. G. gasterostei on fish were affected more by infection temperature than by winter length with implications for parasite growth rate and the fish’s response to infection. While fish that experience different winter lengths acquire immune phenotypes that may reduce S. parasitica infections in cold temperatures. 
