Objective : The presence of a shelter is often not included in enclosure housing of experimental animals, especially in mollusc.  The objective of this experiment was (1) to study how the presence of a shelter would affect the activity and foraging behaviour; (2) to evaluate if the consistency of individual behaviour over time would alter in the presence or absence of this shelter, in a marine gastropod, Haliotis tuberculata.

Methodology : A total of 48 adult european abalone were placed individually in holding aquaria, where half of the aquaria contained crevices to shelter in, and the other half had no shelter. After gently detaching them with a spatula, a reflective tag was glued with cyanoacrylate gel. One abalone was placed in the middle of each aquarium. All tanks were continuously videotaped for 7 days using a digital camera linked to a 24h-recording device. Algae Palmaria palmata was provided ad libitum in the open area. The videos were analysed at 16 times normal speed and slowed to four times when necessary. This procedure was repeated 4 times in total (n = 12 abalone per repetition) during a one-month experiment. The following variables were calculated: total time spent moving and feeding, and number of movement and feeding bouts for each day and night period, and per day. A feeding bout corresponds to the presence of an abalone less than 2 cm from the algae with small movements of the algae observed. If an abalone initiated a movement for at least 2-min, and then came back to the algae, it was considered as another feeding bout.

Results : There was a strong diurnal rhythm of abalone movement during this experiment. When an abalone began moving, it was usually to feed. Significant individual consistency was observed in locomotion as well as in foraging behaviour. However, the absence of a shelter in the experimental set-up it nearly tripled the time spent moving and doubled the number of moving bouts per day. In addition, it reduced the consistency of individual differences in foraging behaviour.

Conclusion : This experiment highlights that it is important to include a shelter in the housing set-up if the species uses one in its ecological niche, including for mollusc species. The higher locomotion probably indicated a reduction of animal welfare with increased motivation to seek a refuge.