Thermal Modulation of Monoamine Levels Influence Fish Stress and Welfare (original) (raw)
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Frontiers in Zoology, 2020
Background: Temperature affects many aspects of performance in poikilotherms, including how prey respond when encountering predators. Studies of anti-predator responses in fish mainly have focused on behaviour, whereas physiological responses regulated through the hypothalamic-pituitary-interrenal axis have received little attention. We examined plasma cortisol and mRNA levels of stress-related genes in juvenile brown trout (Salmo trutta) at 3 and 8°C in the presence and absence of a piscivorous fish (burbot, Lota lota). Results: A redundancy analysis revealed that both water temperature and the presence of the predator explained a significant amount of the observed variation in cortisol and mRNA levels (11.4 and 2.8%, respectively). Trout had higher cortisol levels in the presence than in the absence of the predator. Analyses of individual gene expressions revealed that trout had significantly higher mRNA levels for 11 of the 16 examined genes at 3 than at 8°C, and for one gene (retinol-binding protein 1), mRNA levels were higher in the presence than in the absence of the predator. Moreover, we found interaction effects between temperature and predator presence for two genes that code for serotonin and glucocorticoid receptors. Conclusions: Our results suggest that piscivorous fish elicit primary stress responses in juvenile salmonids and that some of these responses may be temperature dependent. In addition, this study emphasizes the strong temperature dependence of primary stress responses in poikilotherms, with possible implications for a warming climate.
Conservation Physiology, 2017
The frequency of extreme thermal events in temperate freshwater systems is expected to increase alongside global surface temperature. The Miramichi River, located in eastern Canada, is a prominent Atlantic salmon (Salmo salar) river where water temperatures can exceed the proposed upper thermal limit for the species (~27°C). Current legislation closes the river to recreational angling when water temperatures exceed 20°C for two consecutive nights. We aimed to examine how natural thermal variation, representative of extreme high thermal events, affected the thermal tolerance and physiology of wild, juvenile Atlantic salmon. We acclimated fish to four thermal cycles, characteristic of real-world thermal conditions while varying daily thermal minima (16°C, 18°C, 20°C or 22°C) and diel thermal fluctuation (e.g. Δ5°C-Δ9°C). In each cycling condition, we assessed the role that thermal minima played on the acute thermal tolerance (critical thermal maximum, (CTMax)), physiological (e.g. heat shock protein 70 (HSP70), ubiquitin) and energetic (e.g. hepatic glycogen, blood glucose and lactate) status of juvenile Atlantic salmon throughout repeated thermal cycles. Exposure to 16-21°C significantly increased CTMax (+0.9°C) compared to a stable acclimation temperature (16°C), as did exposure to diel thermal fluctuations of 18-27°C, 20-27°C and 22-27°C, yet repeated exposure provided no further increases in acute thermal tolerance. In comparison to the reference condition (16-21°C), consecutive days of high temperature cycling with different thermal minima resulted in significant increases in HSP70 and ubiquitin, a significant decrease in liver glycogen, and no significant cumulative effect on either blood glucose or lactate. However, comparison between thermally taxed treatments suggested the diel thermal minima had little influence on the physiological or energetic response of juvenile salmon, despite the variable thermal cycling condition. Our results suggest that relatively cooler night temperatures in the summer months may play a limited role in mitigating physiological stress throughout warm diel cycle events.
Comp Biochem Physiol A Mol Integr Physiol, 2012
The aim was to elucidate the effects of elevated temperature on growth performance, growth- and appetite-regulating hormones and metabolism in Atlantic salmon, Salmo salar. Post-smolts in seawater (average mass 175 g) that had been reared at 12 °C were kept at three temperatures (8, 12 and 18 °C) and sampled after one and three months. After three months, the fish kept in 18 °C had decreased growth rate and condition factor, and elevated plasma levels of growth hormone (GH) and leptin, compared with fish kept at the lower temperatures. Food conversion efficiency was also decreased at 18 °C, while at the same time protein uptake was improved and thus was not a limiting mechanism for growth. Redistribution of energy stores in fish at the highest temperature is evident as a preference of maintaining length growth during times of limited energy availability. NMR-based metabolomics analyses of plasma revealed that several metabolites involved in energy metabolism were negatively affected by temperature in the upper temperature range of Atlantic salmon. Specifically, the high temperature induced a decline of several amino acids (glutamine, tyrosine and phenylalanine) and a shift in lipid metabolism. It appears likely that the decreased food intake at the highest temperature is linked to an anorexigenic function of leptin, but also that the decreased food intake, feed conversion efficiency and condition factor can be linked to changes in GH endocrinology.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2013
The aim was to elucidate the effects of elevated temperature on growth performance, growth-and appetite-regulating hormones and metabolism in Atlantic salmon, Salmo salar. Post-smolts in seawater (average mass 175 g) that had been reared at 12°C were kept at three temperatures (8, 12 and 18°C) and sampled after one and three months. After three months, the fish kept in 18°C had decreased growth rate and condition factor, and elevated plasma levels of growth hormone (GH) and leptin, compared with fish kept at the lower temperatures. Food conversion efficiency was also decreased at 18°C, while at the same time protein uptake was improved and thus was not a limiting mechanism for growth. Redistribution of energy stores in fish at the highest temperature is evident as a preference of maintaining length growth during times of limited energy availability. NMR-based metabolomics analyses of plasma revealed that several metabolites involved in energy metabolism were negatively affected by temperature in the upper temperature range of Atlantic salmon. Specifically, the high temperature induced a decline of several amino acids (glutamine, tyrosine and phenylalanine) and a shift in lipid metabolism. It appears likely that the decreased food intake at the highest temperature is linked to an anorexigenic function of leptin, but also that the decreased food intake, feed conversion efficiency and condition factor can be linked to changes in GH endocrinology.
Influences of thermal environment on fish growth
Ecology and evolution, 2017
Thermoregulation in ectothermic animals is influenced by the ability to effectively respond to thermal variations. While it is known that ectotherms are affected by thermal changes, it remains unknown whether physiological and/or metabolic traits are impacted by modifications to the thermal environment. Our research provides key evidence that fish ectotherms are highly influenced by thermal variability during development, which leads to important modifications at several metabolic levels (e.g., growth trajectories, microstructural alterations, muscle injuries, and molecular mechanisms). In Atlantic salmon (Salmo salar), a wide thermal range (ΔT 6.4°C) during development (posthatch larvae to juveniles) was associated with increases in key thermal performance measures for survival and growth trajectory. Other metabolic traits were also significantly influenced, such as size, muscle cellularity, and molecular growth regulators possibly affected by adaptive processes. In contrast, a res...
Environmental Science & Policy, 2000
As environmental laws become increasingly protective, and with possible future changes in global climate, thermal effects on aquatic resources are likely to receive increasing attention. Lethal temperatures for a variety of species have been determined for situations where temperatures rise rapidly resulting in lethal effects. However, less is known about the effects of chronic exposure to high (but not immediately lethal) temperatures and even less about stress accumulation during periods of fluctuating temperatures. cumulative thermal stress in fish.
ASSESSING CUMULATIVE THERMAL STRESS IN FISH DURING CHRONIC EXPOSURE TO HIGH TEMPERATURES
As environmental laws become increasingly protective, and with possible future changes in global climate, thermal effects on aquatic resources are likely to receive increasing attention. Lethal temperatures for a variety of species have been determined for situations where temperatures rise rapidly resulting in lethal effects. However, less is known about the effects of chronic exposure to high (but not immediately lethal) temperatures and even less about stress accumulation during periods of fluctuating temperatures. cumulative thermal stress in fish.
Coral Reefs, 2015
Individual exposure to stressors can induce changes in physiological stress responses through modulation of the hypothalamic-pituitary-interrenal (HPI) axis. Despite theoretical predictions, little is known about how individuals will respond to unpredictable short-lived stressors, such as thermal events. We examine the primary neuroendocrine response of coral reef fish populations from the Îles Eparses rarely exposed to anthropogenic stress, but that experienced different thermal histories. Skunk anemonefish, Amphiprion akallopisos, showed different cortisol responses to a generic stressor between islands, but not along a latitudinal gradient. Those populations previously exposed to higher maximum temperatures showed greater responses of their HPI axis. Archive data reveal thermal stressor events occur every 1.92-6 yr, suggesting that modifications to the HPI axis could be adaptive. Our results highlight the potential for adaptation of the HPI axis in coral reef fish in response to a climate-induced thermal stressor.
Stress response to daily temperature fluctuations in common carp, Cyprinus carpio L
Hydrobiologia, 2011
The littoral zone of lakes and lagoons is often used by fish for feeding or reproduction. However, the large changes in temperature that are typical of natural environments, including the littoral zone, represent a potential stressor for fish. Despite the importance of this habitat, little is known about the effect of daily temperature fluctuations on the stress responses of fish. We monitored daily temperature changes in the near-shore and offshore regions of a natural lagoon between May and July 2008-2010. We observed large temperature fluctuations more frequently in the near-shore zone than the offshore zone. We then exposed common carp (Cyprinus carpio) to a temperature regime similar to that observed in the near-shore zone and measured the levels of cortisol released into the water. The rate of cortisol release increased when carp were exposed to an increase in temperature of *0.6°C/h over a 5-h period. Conversely, there was no change in the rate of release when temperatures decreased. Our results highlight the importance of maintaining high temporal resolution when evaluating the stress response to daily fluctuations temperature.
Assessing Cumulative Thermal Stress in Fish During Chronic Exposure to High Temperature
1999
As environmental laws become increasingly protective and with likely future changes in global climate, thermal eects on aquatic resources are likely to receive increasing attention. Lethal temperatures for a variety of species have been determined for situations where temperatures rise rapidly resulting in lethal eects. However, less is known about the eects of chronic exposure to high (but not immediately lethal) temperatures and even less about stress accumulation during periods of¯uctuating temperatures. In this paper we present a modeling framework for assessing cumulative thermal stress in ®sh. The model assumes that stress accumulation occurs above a threshold temperature at a rate dependent on the degree to which the threshold is exceeded. The model also includes stress recovery (or alleviation) when temperatures drop below the threshold temperature as in systems with large daily variation. In addition to non-speci®c physiological stress, the model also simulates thermal eects on growth. Published by Elsevier Science Ltd.