In my study, I aimed to explore the G. anomala / G. aculeatus relationship from the perspective of personality, and parasite-host manipulation. I conducted a novel arena test, a mirror test, and a simulated predator attack test on the fish in my sample. I used these tests to first investigate whether three-spined sticklebacks displayed personality in these setups, and then to investigate how parasitized fish were different from healthy ones. I have shown that three-spined sticklebacks display consistent behavioural variation (i.e. personality), in the context of exploratory behaviour, social behaviour, and antipredator behaviour. With regards to the three-spined stickleback-Glugea anomala system, I have shown that infection status is associated with increased social behaviour and decreased aggressiveness, but personality was not affected in other contexts, that I observed.

The observed link between sociality and parasite load of Glugea infection confirms a link between personality and parasitism, but the causality of the observed relationship between personality and parasite load this needs further investigation to be clarified. Preferentially, experimental infection of future hosts with known personality profiles should be done to determine this.