Author(s):
Castanheira, Maria Filipa Bento de Oliveira Falcão
Date: 2016
Persistent ID: http://hdl.handle.net/10400.1/8997
Origin: Sapientia - Universidade do Algarve
Project/scholarship:
info:eu-repo/grantAgreement/FCT/SFRH/SFRH%2FBD%2F94909%2F2013/PT;
info:eu-repo/grantAgreement/EC/FP7/265957/EU;
Subject(s): Sparus aurata; Aquaculture; Behaviour; Neural activity; Stress response; Welfare; Personality; individual variation; Behavioural syndromes; Domínio/Área Científica::Ciências Naturais::Ciências Biológicas
Description
Tese de doutoramento, Ciências Biológicas, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016
Intensive aquaculture practices frequently expose fish to a range of stressors. Gilthead seabream (Sparus aurata) is the most important farmed species in the Mediterranean, and like in other vertebrates, exhibit pronounced individual differences in stress responsiveness, however to which extent such variability is part of coping styles remains unclear. As such, this Thesis aimed to provide methods and tools to analyse coping styles in seabream, with specific reference to the presence, variability and consistency of individual trait correlations relevant to fish welfare. Using an evolutionary approach, it integrated and explored the adaptive links between behaviour, physiology and brain function, especially aiming to explore individual variation in adaptive responses of seabream when exposed to the same stressful situation. The background and consequences of coping styles in aquaculture is introduced in Chapter 2. Chapter 3 aims to quantify individual differences in cortisol response in seabream and to assess whether it can predict aggressive behaviour. Results provided the first evidence for a link between HPI responsiveness and aggressive behaviour in seabream. This suggests that individual differences in aggression are part of coping styles and therefore can be predictive of and predicted from other traits. In Chapter 4, it was investigated, for the first time in seabream, whether individual differences in behavioural responses to a variety of challenges are consistent over time and across contexts using both individual and grouped-based tests. Results suggest consistency over time and across-context in behavioural responses to challenges both using individual and grouped-based tests. This study highlights the possibility to predict behaviour in groups from individual coping traits. One of the traits that has been shown to be consistent over time and across context in the Chapter 4 was the escape response under a restraining test. Using this trait as a proxy of coping styles in seabream the consistency of escape behaviour was investigated in Chapter 5 and 6. In Chapter 5 we investigated the effect of avoidance in gilthead seabream kept under different social contexts, i.e. the influence of other group members on individual avoidance behaviour consistency. The results demonstrate that grouping individuals with similar coping styles induces changes in coping styles whereas grouping individuals with different coping styles favours coping styles to remain the same. These findings suggest an influence of the social environment in seabream coping styles. In Chapter 6 we investigate the long term consistency of coping styles both, over time and during different life history stages. Our results show consistent behaviour traits in seabream when juveniles, and a loss of these behavioural traits when adults. Therefore, these results underline that adding a life history approach to data interpretation is as an essential step forward towards understanding coping styles. Chapter 7 aimed to characterize the stress coping ability and brain function in seabream, by investigating the behavioural and forebrain physiological responses of fish displaying contrasting coping styles to the same stimulus (escape response under a restraining test). Results show differences in activation of region-specific telencephalic regions between seabream displaying contrasting coping styles. It confirms the hypothesis that in seabream, inhibitory and excitatory markers of neural function appear to be associated with reactive and proactive coping styles, respectively. The main findings of this thesis are discussed and the main conclusions are presented in Chapter 8. It is concluded that fish with contrasting stress coping styles show clear differences in behavioural and physiological parameters. Moreover, these differences can change according to social environment and life history. In general this Thesis has generated new knowledge of the mechanisms underlying individual responses of fish to stress providing new insights on the interrelations between different relevant husbandry practices, fish performance and welfare.
