Habituation as a tool to interpret an open field test adapted for juvenile lemon sharks (Negaprion brevirostris) (#310)
Personality differences are widespread throughout the animal kingdom and represent individual behavioral variations that are consistent over time. They are known to have important ecological and evolutionary consequences and as such ‘standardized’ or ‘popular’ assays have been developed and used across taxa, such as activity in an open field (AOF). However such tests are not easily transferable or comparable from one species to another, thus it remains a challenge to understand and interpret which trait is represented by a specific test especially for studies on novel species. Here we use the juvenile lemon shark (JLS) (Negaprion brevirostris) to address this challenge by investigating activity in an open field (AOF). Unlike bony fishes, JLS cannot be neutrally buoyant and have to swim continuously to avoid sinking; therefore AOF could represent reaction to novelty or activity in this species. We repeatedly exposed JLS to an open-field: if AOF represented a reaction to novelty we would expect it to vary with the number of exposures according to the dual-process theory.
Twenty-eight JLS were captured intermittently over a 6-month period in Bimini, Bahamas. Sharks were housed in a semi-captive holding pen built in shallow water and tested every other day (for 6 replicates). The open-field consisted of a large rectangular pen split into 18 zones by markers on the sea floor; the number of zones visited by the shark during the test was used as a measure of AOF. Using linear mixed-models and controlling for environmental influence, AOF (repeatability=0.24) was shown to indicate reaction to novelty since habituation was expressed by all individuals. Interestingly a difference in inter-individual response variation was observed, with more explorative individuals habituating faster. This study emphasizes the importance of examining the validity of personality tests when adapting them to new species, and proposes an effective approach to this challenge.