Behaviour, physiology and carotenoid pigmentation in Arctic charr Salvelinus alpinus

The behaviour during an exploration task and the response to a confinement stress of Arctic charr Salvelinus alpinus were evaluated. Behaviour of individuals during 90 min of exploration was classified into high and low activity. High-activity individuals had higher plasma cortisol levels following stress compared to low-activity individuals. This indicates that high- and low-activity individuals correspond to reactive and proactive stress-coping styles. Further, a pigmentation analysis showed that high-activity individuals had a higher number of carotenoid spots cm(-2) than low-activity individuals. Thus, carotenoid pigmentation, as melanin pigmentation in other salmonids, could be linked to stress-coping style in S. alpinus. (C) 2013 The Fisheries Society of the British Isle

Invasive round goby shows higher sensitivity to salinization than native European perch

Salinity is an influential abiotic environmental factor in aquatic species, specifically in freshwater, where salinization causes ecosystem degradation. Secondary salinization, that is increases in salinity due to anthropogenic activities, can affect both osmoregulation and behaviour in freshwater fishes. It is generally believed that invasive species handle climatic change and environmental degradation better than native species, which is one reason for their invasion success. However, how invasive and native species cope with salinity changes remains little understood. Therefore, we investigated how low (500 µS/cm) and high salinity (2000 µS/cm) conditions affected oxygen consumption and behaviour in the invasive round goby (Neogobius melanostomus) and the native European perch (Perca fluviatilis). Our results showed that in round goby oxygen consumption increased and swimming and non-swimming movements changed in response to salinity increments, whereas European perch was not affected by salinity. Thus, it seems as if the invasive round goby is more sensitive to changes in salinity than the native European perch. Our results fit with the minority of studies indicating invasive species being less tolerant than some native species to environmental changes. This finding could be explained by the adaptation of round goby to low salinity due to its long establishment in River Rhine. Further, our results are also confirming that the effect of salinity is species-specific. In addition, European perch and round goby show diametrically different behavioural response to disturbance which could be an effect of holding different ecological niches as well as their anatomical differences

The effect of anesthetics on carotenoid pigmentation and behavior in Arctic char (Salvelinus alpinus)

Status of individual animals is often shown in pigmentation. For instance, stress responsiveness is associated with melanin-based pigmentation in vertebrates in general. This pattern is evident in Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss), with melanin-based spots indicating stress coping style. Arctic char (Salvelinus alpinus) differ from other salmonids in pigmentation but have an association between carotenoid-based pigmentation and stress coping style. These pigmentation differences could be used as a fast and simple tool for improving breeding programs. However, the procedure for photographing individuals is stressful. Therefore, we wanted to investigate if 3 common inhalation anesthetics could be used to reduce the stress involved in the procedure compared to a no-anesthetics group. Behavior was also monitored during the anesthetization. All 3 anesthetics (Aquacalm, Benzocaine, and MS-222) differed in pigmentation compared to the no-anesthetics group by having a higher number of spots. In the anesthetic treatments as well as the no-anesthetics group, the fish had elevated plasma cortisol levels. In fact, the no-anesthetics group had higher cortisol than treated fish. This was probably because of procedural differences such as time affecting the stress response. Furthermore, in a long-term experiment, all fish survived and had similar condition factors 1 week after photographing as before. Therefore, the method for photographing Arctic char is deemed safe and could be used as a tool for estimating stress coping style, but careful planning is needed for experiments using i

Dominance and stress signalling of carotenoid pigmentation in Arctic charr (Salvelinus alpinus): Lateralization effects?

Social conflicts are usually solved by agonistic interactions where animals use cues to signal dominance or subordinance. Pigmentation change is a common cue used for signalling. In our study, the involvement of carotenoid-based pigmentation in signalling was investigated in juvenile Arctic charr (Salvelinus alpinus). Size-matched pairs were analysed for pigmentation both before and after being tested for competitive ability. We found that dominant individuals had fewer carotenoid-based spots on the right and left sides as well as lower plasma cortisol levels compared to subordinate individuals. Further, the number of spots on both sides was positively associated with plasma cortisol levels. These results indicate that carotenoid-based pigmentation in Arctic charr signals dominance and stress coping style. Further, it also appears as if carotenoid-based pigmentation is lateralized in Arctic charr, and that the right side signals aggression and dominance whereas the left side signals stress responsiveness

Divergence in behavioural responses to stress in two strains of rainbow trout (Oncorhynchus mykiss) with contrasting stress responsiveness

The aim of this study was to establish whether two lines of rainbow trout divergent for their plasma cortisol response to a standardized stressor would show consistent differences in their behavioural response to a range of challenging situations. Our results show that the high- and low-responding (HR and LR) lines of rainbow trout did not differ in the aggression shown towards an intruder or in their response to the introduction of a novel object to their home environment. However, there was a difference in behaviour between the two selection lines when they were exposed to two unfamiliar environments. These results suggest that the behaviour of the HR and LR fish differs when they are challenged in unfamiliar environments, while their behaviour does not differ when they are challenged in their home environment. These observations are in agreement with studies on mammals that show that individuals with reactive coping styles perform similarly to proactive animals when they are challenged in a familiar environment, while they show different behaviour when they are challenged in unfamiliar environments. Thus, these results provide further evidence that the HR and LR selection lines of rainbow trout exemplify the two different coping styles described in mammals

Anaesthesia and handling stress effects on pigmentation and monoamines in Arctic charr

Stress responsiveness differs between individuals and is often categorized into different stress coping styles. Using these stress coping styles for selection in fish farming could be beneficial, since stress is one main factor affecting welfare. In Arctic charr (Salvelinus alpinus) carotenoid pigmentation is associated with stress responsiveness and stress coping styles. Thus this could be an important tool to use for selection of stress resilient charr. However, anaesthetics seem to affect carotenoid pigmentation, and it would be better if the method for selection could be implemented during normal maintenance, which usually includes anaesthetics. Therefore, this study investigated how the use of anaesthetics affected carotenoid pigmentation, i.e. number of spots, over time compared to no-anaesthetic treatment. Additionally, the stress indicators monoamines and glucocorticoids were investigated. The results indicate that the anaesthetic MS-222 affects number of spots on the right side. This anaesthetic also increased dopaminergic activity in the telencephalon. Both brain dopaminergic and serotonergic activity was associated with spottiness. Further, behaviour during anaesthetization was associated with spots on the left side, but not the right side. Repetition of the same treatment seemed to affect spot numbers on the right side. In conclusion, this study shows that inducing stress in charr affects the carotenoid spots. Thus, it is possible to use anaesthetics when evaluating spottiness although careful planning is needed

Roles of Arginine-Vasotocin and Corticotropin-Releasing Hormone in Stress Responses and Agonistic Behaviour of Rainbow Trout

The neuropeptides arginine-vasotocin (AVT) and corticotropin-releasing hormone (CRH) are involved in the hypothalamic-pituitary-interrenal (HPI) axis. During stress, the HPI axis is activated and cortisol is released into the blood. In addition to their role in the HPI axis, AVT and CRH also have behavioural effects. The roles of AVT and CRH in stress responses and agonistic behaviour were studied in this thesis, using two different models. In the first model, two strains of rainbow trout (Onchorhynchus mykiss) divergent in stress-induced release of cortisol were investigated. This was done by observing behaviour and stress responses under different conditions. These strains were found to have divergent stress coping strategies based on the observed behaviour and levels of plasma cortisol. This divergence in behaviour could be associated with the CRH system, since the mRNA levels of CRH differed between the strains during stress. However, no differences between strains were observed in AVT or its receptor expressions. In the second model, non-selected rainbow trout were paired and the effect of intracerebroventricular (icv) injections of an active substance (AVT, CRH or the CRH related peptide Urotensin-I (UI)) on fights for dominance was investigated. One fish of the pair received the active substance icv and the other received saline icv. Fish receiving AVT became subordinate in accordance with the suggestion that AVT attenuates aggression in territorial vertebrates. Fish receiving CRH became subordinate whereas UI showed no effect on fights for dominance. Further, both CRH and UI induced an anxiety-related behaviour similar to non-ambulatory motor activity in rats. In addition, CRH appeared to affect the dopaminergic and serotonergic systems. In this thesis, it is suggested that CRH is involved in the behavioural modulation of the stress coping strategies in teleost fish. Further, AVT and CRH seem to act inhibitory on aggressive behaviour

Invasive round goby shows higher sensitivity to salinization than native European perch

Salinity is an influential abiotic environmental factor in aquatic species, specifically in freshwater, where salinization causes ecosystem degradation. Secondary salinization, that is increases in salinity due to anthropogenic activities, can affect both osmoregulation and behaviour in freshwater fishes. It is generally believed that invasive species handle climatic change and environmental degradation better than native species, which is one reason for their invasion success. However, how invasive and native species cope with salinity changes remains little understood. Therefore, we investigated how low (500 µS/cm) and high salinity (2000 µS/cm) conditions affected oxygen consumption and behaviour in the invasive round goby (Neogobius melanostomus) and the native European perch (Perca fluviatilis). Our results showed that in round goby oxygen consumption increased and swimming and non-swimming movements changed in response to salinity increments, whereas European perch was not affected by salinity. Thus, it seems as if the invasive round goby is more sensitive to changes in salinity than the native European perch. Our results fit with the minority of studies indicating invasive species being less tolerant than some native species to environmental changes. This finding could be explained by the adaptation of round goby to low salinity due to its long establishment in River Rhine. Further, our results are also confirming that the effect of salinity is species-specific. In addition, European perch and round goby show diametrically different behavioural response to disturbance which could be an effect of holding different ecological niches as well as their anatomical differences

Hållbar, hållbarare, hållbarast! : En kvantitativ studie som jämför Morningstars hållbarhetsbetyg i förhållande till risk och avkastning för svenskregistrerade fonder

Seven out of ten Swedes save voluntarily in funds, and if premium pensions and pension savings are taken into account, almost all adults save. In recent years, there has been a growing interest in sustainable funds, with more than a third choosing a sustainable fund to invest in. There is a disagreement in the existing research as to whether sustainable funds are a better option than conventional ones.  The study examined whether sustainable funds underperformed conventional funds on the variables of return, standard deviation and Sharpe ratio. The study's measurement period covered 21 April 2019 to 21 April 2024, for Swedish-registered funds in the industrial sector. The study conducted a quantitative approach using t-tests and regression analyses to examine performance across categories. The study obtained secondary data from Morningstar and used the Morningstar Sustainability Rating to categorise the funds. Funds with a rating of 1-3 were defined as conventional and sustainable as those with a rating of 4-5.  From the data collected in the study, the authors concluded that the t-test between conventional and sustainable funds was significant based on the standard deviation variable, while the other variables were not significant. Like the t-test, the regression analysis between sustainability ratings and standard deviation was significant and the other regressions were not significant. The study does not find that sustainable funds are characterised by lower returns, higher risk or lower risk-adjusted returns compared to conventional funds. Sju av tio svenskar sparar frivilligt i fonder och tar man hänsyn till premiepensionen och pensionssparande så sparar nästan alla vuxna. Under de senare åren har det växt fram ett intresse för hållbara fonder, där mer än en tredjedel har valt en hållbar fond att investera i. Det finns en oenighet i den befintliga forskningen huruvida hållbara fonder är ett bättre alternativ än konventionella.  Studien undersökte om hållbara fonder presterade sämre än konventionella fonder utifrån variablerna avkastning, standardavvikelse och Sharpekvot. Studiens mätperiod avsåg 2019-04-21 till 2024-04-21, för svenskregistrerade fonder inom industrisektorn. Studien genomförde en kvantitativ ansats med hjälp av t-tester och regressionsanalyser för att undersöka prestationen mellan kategorierna. Studien inhämtade sekundärdata från Morningstar och har använt Morningstar Sustainability Rating för att kategorisera fonderna. Fonder som innehar 1-3 i betyg definierades som konventionella och hållbara som innehar 4-5 i betyg.  Av studiens inhämtade data, konstaterade författarna att t-testet mellan konventionella och hållbara fonder var signifikant utifrån variabeln standardavvikelse medan de övriga variablerna inte var signifikanta. Likt t-testet var regressionsanalysen mellan hållbarhetsbetyg och standardavvikelse signifikant och de övriga regressionerna var ej signifikanta. Studien kan inte konstatera att hållbara fonder kännetecknas av en lägre avkastning, en högre risk eller en lägre riskjusterad avkastning gentemot konventionella fonder.