The importance of attitude: the influence of behaviour on survival at an ontogenetic boundary

Abstract

Behavioural traits can strongly influence fitness and survival and are important mediators of life history trade-offs. This study explored the links between mortality trade-offs associated with fast growth during larval life and behaviour of individuals during an important life history transition. Longitudinal sampling of a cohort of damselfish settling on a reef at the end of their larval stage found that individuals with small otolith sizes at hatching and low otolith growth rates were selectively removed from the local population, while there was no apparent selection for size or body condition over the first 24 h after settlement. Selection against slow growth (initial larval growth and maximum growth) and small size at hatching and settlement were accentuated over the first month after settlement. Detailed behavioural assessments of naïve larvae settled onto habitat patches and monitored for 24 h found that initial boldness aided survival, but individuals that ventured larger distances from shelter suffered higher mortality. Correlations of growth with behavioural attributes were generally poor; however, there was a weak correlation between boldness and maximum growth. A measure of flexibility in the maximum distance ventured from shelter was positively related to initial otolith growth. Our results suggest that although early growth which is relatively slow leads to higher mortality later in life, and behavioural attributes influenced survival, there were only weak correlations between growth history and behaviour. This may be due to strong selective pressures on young fish to learn novel behaviours rapidly after settlement. Selection may promote behavioural flexibility at this key ecological transition.

Learn and live: predator experience and feeding history determines prey behaviour and survival

“…Survival was monitored twice a day for 70 to 96 h after release. Previous tagging studies suggest that migration between patches or to the main reef is negligible [17,21,28]. In this study, there were no instances where two fish were found on a single patch reef.…”

“…Adults and juveniles occur in shallow lagoons, where they inhabit the reef edge or reef top associated with rubble. Larval duration is 16-21 days, with fish reaching 13-14 mm standard length (SL) at the end of the larval stage [17]. Fish can potentially disperse hundreds of kilometres from their natal location [18], and newly metamorphosed fish settle as solitary individuals into habitats with conspecific adults and sub-adults.…”

“…At the end of the 3 min observation period, the fish were approached with a pencil, and the fish's reaction and latency to emerge from shelter was taken into account in the assessment of boldness. This measure of boldness has been found to be repeatable between observers, consistent in the short term for newly settled damselfish and related to survival in the field ( [17]; M. I. McCormick 2009, unpublished data). The number of replicate fish for each of the 8 factor combinations (2 food levels  2 visual levels  2 olfactory levels) ranged from 23 to 27 depending upon availability of fish in light trap catches.…”

“…All predators can be seen striking at and occasionally capturing recently settled and juvenile reef fishes during the summer recruitment period. Studies that have monitored newly settled damselfish that were individually identified through tagging have found high levels of mortality in the first few days after settlement, with high levels of variability among sites located hundreds of metres apart [17,19,21].…”

“…(c) Behavioural assessment Following acclimation, the behaviour of fish was quantified for 3 min following previously developed protocols [17,28,33,34]. Briefly, the behaviour of each fish was assessed by a scuba diver positioned approximately 1 m away from the patch.…”