Shelter fidelity and exploratory behaviours of juvenile Haliotis discus hannai in response to different stressors

Abstract

Individual differences in behavioural responses to stressors are categorised as adaptive variation and serve as a foundation for devising improvements in animal health and welfare. However, the existence of different coping styles in response to stress has not been demonstrated in marine gastropods. To evaluate individual differences in shelter fidelity and exploratory levels of abalones in response to stress, the behaviours of juvenile Pacific abalones (Haliotis discus hannai) housed in tanks were observed; several behavioural parameters such as forage duration and un-sheltering behaviour were also measured and analysed. To test differences in survival rates between individuals that showed staying (returning to home shelters after foraging) and wandering (not returning to home shelters after foraging) behaviours in response to poor water quality, 90 1-year-old abalones were exposed to hypoxia stress caused by interrupted water flow. To assess the individuals’ exploratory behaviours, 150 1.5-year-old abalones were supplied with excess food inside their shelters, and their movement between the shelters was recorded. Differences in behavioural parameters between the exploratory and nonexploratory individuals in the presence of resident intruders were also tested. Our results showed that (1) staying abalones exhibited higher survival rates than their wandering counterparts under hypoxic stress; (2) the number of shelters visited in one night could be considered as an exploratory activity under conditions of sufficient food availability within the shelters; and (3) in the presence of intruders, both the exploratory and nonexploratory abalones displayed reduced shelter-seeking activity, although the reduction was more pronounced in the exploratory than the nonexploratory abalones.