AQUAculture infrastructures for EXCELLence in European Fish research

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Thermal preference predicts animal personality in Nile tilapia Oreochromis niloticus

Publication . Cerqueira, Marco; Rey, Sonia; Silva, Tome; Featherstone, Zoe; Crumlish, Margaret; MacKenzie, Simon

1. Environmental temperature gradients provide habitat structure in which fish orientate and individual thermal choice may reflect an essential integrated response to the environment. The use of subtle thermal gradients likely impacts upon specific physiological and behavioural processes reflected as a suite of traits described by animal personality. In this study, we examine the relationship between thermal choice, animal personality and the impact of infection upon this interaction.2. We predicted that thermal choice in Nile tilapia Oreochromis niloticus reflects distinct personality traits and that under a challenge individuals exhibit differential thermal distribution.3. Nile tilapia were screened following two different protocols: 1) a suite of individual behavioural tests to screen for personality and 2) thermal choice in a custom-built tank with a thermal gradient (TCH tank) ranging from 21 to 33 degrees C. A first set of fish were screened for behaviour and then thermal preference, and a second set were tested in the opposite fashion: thermal then behaviour. The final thermal distribution of the fish after 48 h was assessed reflecting final thermal preferendum. Additionally, fish were then challenged using a bacterial Streptococcus iniae model infection to assess the behavioural fever response of proactive and reactive fish.4. Results showed that individuals with preference for higher temperatures were also classified as proactive with behavioural tests and reactive contemporaries chose significantly lower water temperatures. All groups exhibited behavioural fever recovering personality-specific thermal preferences after 5 days.5. Our results show that thermal preference can be used as a proxy to assess personality traits in Nile tilapia and it is a central factor to understand the adaptive meaning of animal personality within a population. Importantly, response to infection by expressing behavioural fever overrides personality-related thermal choice.

2016-09Journal article

Restricted

Habituation and conditioning in gilthead sea bream (Sparus aurata): effects of aversive stimuli, reward and social hierarchies

Publication . Folkedal, Ole; Ferno, Anders; Nederlof, Marit A. J.; Fosseidengen, Jan E.; Cerqueira, Marco; Olsen, Rolf E.; Nilsson, Jonatan

To tailor the farming environment to a fish species, we should understand the species-specific responses to stimuli, including the degree of adaption and learning. Groups of gilthead sea bream were given a delay Pavlovian conditioning regime using a conditioning stimulus (CS) of light flashes signalling arrival of food. Controls were exposed to light flashes unrelated to feeding. Fish in both treatments showed an initial fear response of moving away from the CS combined with reduced swimming speed. In subsequent trials, the Control fish largely habituated the fleeing response but sustained to respond by reducing the swimming speed. The Conditioning fish also stopped to escape from the CS, but opposed to the Control group they gradually increased their swimming speed in response to the CS. In addition, the number of fish in the feeding/CS area increased and became similar to basal level after around 16 trials. A small and variable proportion of the fish displayed black vertical bands on their body and territorial behaviour, and a social hierarchy could interfere with the processes of habituation and conditioning. The swimming speed of the fish increased with number of dark individuals, but this was not found during the CS and the light stimulus thus seemed to overrule the effect of territorial behaviour. The persistent negative response to light flashes in the Control suggests that fish seemingly adapted to repetitive stressors are still in a state of alertness. The change in the response to light shows the potential for rewarding aversive stimuli to reduce stress.

2018-01Journal article

Restricted

Linking personality and appraisal modulators in fish

Publication . Cerqueira, Marco Alexandre Cavaco; Dinis, Maria Teresa; Oliveira, Catarina; Oliveira, Rui F.; Mackenzie, Simon

The reason why some individuals from the same fish population react so differently under similar aquaculture husbandry practices or to any other stressful situation is at the core of today’s fish welfare research. In this context, the large individual variation in the physiological or behavioural response under stressful conditions is now accepted as reflection of distinct personality traits and of divergent cognitive evaluation that the individual makes of the situation, i.e. on the way the stressor is appraised. This thesis aimed to uncover which appraisal criteria fish use, the interplay with their personality traits, the underlying neurophysiological mechanisms and the potential application of psychological modulators of the stress response to improve fish welfare. Thus, the experimental work was oriented towards: i) investigating whether pre-existing inherent traits in behaviour and physiology affect the outcome of exposure to environmental stressors in Gilthead seabream (Sparus aurata) and Atlantic seabass (Dicentrarchus labrax) (Chapter II.1 and Chapter II.2); ii) evaluating the effect of predictability on the onset of action-related responses to aversive and appetitive stimuli (Chapter III.1); iii) inferring how predictability stressor modulates the cognitive stress response (Chapter III.2); iv) investigating how controllability improves coping ability on both seabream and seabass (Chapter IV.1); v) examining the relationship between thermal choice and animal personality using Nile tilapia (Oreochromis niloticus) as model (Chapter IV.2). Differences in behaviour, physiology and brain states measurements support specific appraisal and motivations in fish, according to the prospect of reward or punishment. This seems to be, nevertheless, highly dependent of both species - and contextspecificity. In addition they suggest that predictable stimuli and social support alongside with perception of control can be used as psychological modulators of the stress response to make animals more resilient and empowered under sustainable farming systems. The link between personality and appraisal deserves further investigation as evidences are narrow. The work developed in the core of this thesis has brought new insights on how to manipulate fish´s ability to cope with changes in their environment, ensuring positive outcomes in terms of welfare, fitness and survival.

2016-11-29Doctoral thesis

Open Access

European Sea Bass (Dicentrarchus labrax) immune status and disease resistance are impaired by arginine dietary supplementation

Publication . Azeredo, Rita; Perez-Sanchez, Jaume; Sitja-Bobadilla, Ariadna; Fouz, Belen; Tort, Lluis; Aragao, Claudia; Oliva-Teles, Aires; Costas, Benjamin

Infectious diseases and fish feeds management are probably the major expenses in the aquaculture business. Hence, it is a priority to define sustainable strategies which simultaneously avoid therapeutic procedures and reinforce fish immunity. Currently, one preferred approach is the use of immunostimulants which can be supplemented to the fish diets. Arginine is a versatile amino acid with important mechanisms closely related to the immune response. Aiming at finding out how arginine affects the innate immune status or improve disease resistance of European seabass (Dicentrarchus labrax) against vibriosis, fish were fed two arginine-supplemented diets (1% and 2% arginine supplementation). A third diet meeting arginine requirement level for seabass served as control diet. Following 15 or 29 days of feeding, fish were sampled for blood, spleen and gut to assess cell-mediated immune parameters and immune-related gene expression. At the same time, fish from each dietary group were challenged against Vibrio anguillarum and survival was monitored. Cell-mediated immune parameters such as the extracellular superoxide and nitric oxide decreased in fish fed arginine-supplemented diets. Interleukins and immune-cell marker transcripts were down-regulated by the highest supplementation level. Disease resistance data were in accordance with a generally depressed immune status, with increased susceptibility to vibriosis in fish fed arginine supplemented diets. Altogether, these results suggest a general inhibitory effect of arginine on the immune defences and disease resistance of European seabass. Still, further research will certainly clarify arginine immunomodulation pathways thereby allowing the validation of its potential as a prophylactic strategy.

2015-10Journal article

Open Access

Dietary butyrate helps to restore the Intestinal status of a marine teleost (Sparus aurata) fed extreme diets low in fish meal and fish oil

Publication . Estensoro, Itziar; Ballester-Lozano, Gabriel; Benedito-Palos, Laura; Grammes, Fabian; Martos-Sitcha, Juan Antonio; Mydland, Liv-Torunn; Calduch-Giner, Josep Alvar; Fuentes, Juan; Karalazos, Vasileios; Ortiz, Alvaro; Overland, Margareth; Sitja-Bobadilla, Ariadna; Perez-Sanchez, Jaume

There is a constant need to find feed additives that improve health and nutrition of farmed fish and lessen the intestinal inflammation induced by plant-based ingredients. The objective of this study was to evaluate the effects of adding an organic acid salt to alleviate some of the detrimental effects of extreme plant-ingredient substitution of fish meal (FM) and fish oil (FO) in gilthead sea bream diet. Three experiments were conducted. In a first trial (T1), the best dose (0.4%) of sodium butyrate (BP-70 (R) NOREL) was chosen after a short (9 weeks) feeding period. In a second longer trial (T2) (8 months), four diets were used: a control diet containing 25% FM (T2-D1) and three experimental diets containing 5% FM (T2-D2, T2-D3, T2-D4). FO was the only added oil in D1, while a blend of plant oils replaced 58% and 84% of FO in T2-D2, and T2-D3 and T2-D4, respectively. The latter was supplemented with 0.4% BP-70. In a third trial (T3), two groups of fish were fed for 12 and 38 months with D1, D3 and D4 diets of T2. The effects of dietary changes were studied using histochemical, immunohistochemical, molecular and electrophysiological tools. The extreme diet (T2-D3) modified significantly the transcriptomic profile, especially at the anterior intestine, up-regulating the expression of inflammatory markers, in coincidence with a higher presence of granulocytes and lymphocytes in the submucosa, and changing genes involved in antioxidant defences, epithelial permeability and mucus production. Trans-epithelial electrical resistance (Rt) was also decreased (T3-D3). Most of these modifications were returned to control values with the addition of BP-70. None of the experimental diets modified the staining pattern of PCNA, FABP2 or ALPI. These results further confirm the potential of this additive to improve or reverse the detrimental effects of extreme fish diet formulations.

2016-11Journal article

Open Access