Effect of Confinement on Water-borne and Whole Body Cortisol in Wild and Captive-reared Rainbowfish (Melanoteania duboulayi) (original) (raw)
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Aquaculture, 2011
The stress response of wild and captive reared rainbowfish (Melanoteania duboulayi) following chasing by a simulated predator was examined. Cortisol release rate was monitored using a flow through system by measuring water borne hormone levels. Tests using known cortisol concentrations revealed that the technique yielded 95% of the cortisol present in the water. Cortisol release rates increased several fold in both populations after being chased but peaked at different time periods. Wild fish showed a typical stress response with release rate rising to (2.29 ± 0.22 ng g − 1 h − 1 ) 2 h after exposure followed by rapid recovery. The captive-reared population by contrast showed an atypical response with cortisol release rate peaking 4 h post exposure but reaching only half the level of the wild fish (1.19 ± 0.11 ng g − 1 h − 1 ). The implications for the release of hatchery-reared fish for stock enhancement are discussed.
North American Journal of Aquaculture, 2012
The San Pedro (also known as the Pacific beakfish) Oplegnathus insignis is a species of perciform fish found in the eastern Pacific Ocean. In northern Chile, San Pedro are an important food fish currently being evaluated for aquaculture. The purpose of this study was to conduct an initial evaluation of the cortisol stress response in captive-bred San Pedro. The fish were subjected to confinement stress by crowding them into a low volume of water (231 kg/m 3 ) for 90 min. Blood was collected over time for the determination of plasma cortisol. Confinement resulted in a significant increase in plasma cortisol, from a resting concentration of 24.9 ng/mL to 120.7 ng/mL after 10 min into the stress experience. After 20 and 60 min of stress, cortisol concentrations plateaued at 225.3 ng/mL and 243.7 ng/mL, respectively, followed by a decrease to 56.1 ng/mL by 90 min. These results indicate a rapid and robust cortisol stress response in this species. This is the first evaluation of the San Pedro stress response, and these data will serve as the baseline for future evaluations of San Pedro stress physiology and the development of aquaculture techniques suitable for this species.
Fish Physiology and Biochemistry, 2012
Previous reviews of stress, and the stress hormone cortisol, in fish have focussed on physiology, due to interest in impacts on aquaculture production. Here, we discuss cortisol in relation to fish welfare. Cortisol is a readily measured component of the primary (neuroendocrine) stress response and is relevant to fish welfare as it affects physiological and brain functions and modifies behaviour. However, we argue that cortisol has little value if welfare is viewed purely from a functional (or behavioural) perspective-the cortisol response itself is a natural, adaptive response and is not predictive of coping as downstream impacts on function and behaviour are dose-, time-and context-dependent and not predictable. Nevertheless, we argue that welfare should be considered in terms of mental health and feelings, and that stress in relation to welfare should be viewed as psychological, rather than physiological. We contend that cortisol can be used (with caution) as a tractable indicator of how fish perceive (and feel about) their environment, psychological stress and feelings in fish. Cortisol responses are directly triggered by the brain and fish studies do indicate cortisol responses to psychological stressors, i.e., those with no direct
Journal of Experimental Zoology Part A: Ecological Genetics and Physiology, 2012
Wild fish are frequently exposed to multiple stressors, but the influence of previous or ongoing stress on an animal's subsequent response is poorly understood. Using wild-caught bluegill sunfish (Lepomis macrochirus) as a model, we used exogenous hormone implants to experimentally raise circulating cortisol in a group of fish for ∼10 days. We also maintained sham-treated and control groups of fish. We subjected all animals to a secondary stressor in the form of either a heat challenge or fasting challenge. We compared survival, body condition, and plasmaborne indicators of physiological status among cortisol-treated, sham-treated, and control groups following the secondary stressor. In order to compare short-and long-term effects of cortisol treatment, we initiated the secondary stressor either 4 or 30 days following initial cortisol treatment. Cortisol-treated fish succumbed to the fasting challenge sooner than sham-treated and control fish at both 4 and 30 days. Interestingly, cortisol-treated fish lost equilibrium sooner than sham-treated and control fish during the heat challenge when conducted at 30 days, but not at 4 days. These results demonstrate that multiple simultaneous stressors have cumulative effects on bluegill sunfish. Furthermore, these results demonstrate that supraphysiological cortisol doses alter the long-term responses of bluegill sunfish to additional challenges, even after apparent recovery. Such cumulative and long-term effects may be an important factor in mediating the response of wild animals to natural and anthropogenic stressors, and should be considered in ecological studies.
Condition dependent intra-individual repeatability of stress-induced cortisol in a freshwater fish
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2012
The glucocorticoid (GC) stress response is thought to be an individual trait associated with behaviour and life history strategies. Studies exploring such relationships typically assume measured hormone values to be repeatable within an individual. However, repeatability of GCs has proven variable in wild animals and underlying reasons remain unknown. We assessed individual repeatability of circulating stress-induced cortisol, the primary GC in teleost fish, and glucose concentrations in a wild teleost fish held under consistent laboratory conditions. We also tested the hypothesis that the magnitude of intra-individual variability in stressinduced cortisol concentrations ("cortisol variability") is influenced by body condition. Wild-caught bluegill sunfish (Lepomis macrochirus) were subjected to repeated standardized stressors and blood sampled (3 times over 6 days) once cortisol concentrations peaked. Various indicators of fish condition, both whole body and physiological, were also measured. Overall, stress-induced circulating cortisol concentrations were repeatable but stress-induced glucose was not. Cortisol variability was related to Fulton's condition factor and size (eviscerated mass) where smaller fish in poor condition exhibited increased cortisol variability. The findings have implications for the interpretation of studies that examine correlates of GC concentrations as they suggest consistency in stress responsiveness is influenced by factors such as size and condition.
Journal of The World Aquaculture Society, 1992
A commercially available heterogeneous, solid-phase tube enzyme-linked immunoassay (ELISA) was modified and validated for the measurement of serum cortisol in rainbow trout Oncorhynchus mykiss. The assay is accurate and precise. Resting and stress-elevated serum cortisol concentrations were measured in rainbow trout with a sensitivity of 1.5 ng/ml. Fish held in net-pens at a density of 0.4 kg/m3/cm had a resting cortisol level of 16.5 f 3.8 ng/ml (mean f SE). At 3 h postdisturbance, serum cortisol levels were not affected by the removal of fish from adjacent net-pens with dip nets or by the use of 200 mg/L tricaine methanesulfonate (MS-222) as an anesthetic for obtaining samples. However, an acute stress (60 s removal from water) elevated serum cortisol levels to 73.7 +. 9.4 ng/ml.
Conservation Physiology, 2019
The development of chronic stress indicators for fish is of great interest, but appropriate non-invasive methods are lagging those used in terrestrial vertebrates. Here, we explore the possibility that levels of the stress hormone cortisol in scales could be used as a chronic stress indicator. Three experiments were conducted to assess the temporal profiles of cortisol rise and fall in plasma and scales of goldfish (Carassius auratus) in response to stressors of varying intensity and duration. Results show that a single acute air emersion stressor does not influence scale cortisol content. In contrast, relative to plasma levels, the fall in scale cortisol content following a high-dose cortisol implant is delayed by at least 8 days, and the rise and fall in scale cortisol content in response to unpredictable chronic stress are delayed by at least 7 days. Also, scale cortisol content is spatially heterogeneous across the body surface of goldfish. Overall, since high and sustained circ...
Physiological and Biochemical Zoology, 2009
Male largemouth bass (Micropterus salmoides) provide sole parental care over a 4-6-wk period to a single brood, fanning the eggs to keep them oxygenated and free of silt and defending the brood until the offspring develop antipredator tactics. During this period, fish are highly active and have few opportunities for feeding, so this activity is energetically costly. To understand some of the consequences of stress during this challenging period, we injected fish with cortisol suspended in coconut oil to experimentally raise circulating cortisol in parental males for the first week of the parental care period. We compared parental care behavior between cortisol-treated, sham-treated (injected only with coconut oil), and control parental males. We further compared physiological parameters associated with metabolism and reproductive function between cortisol-treated and control males. The cortisol injections resulted in supraphysiological levels of circulating plasma cortisol, giving us insight into po-tential maximal effects of stress during parental care. At these supraphysiological levels, the cortisol-treated fish displayed higher concentrations of circulating glucose and cholesterol and lower concentrations of circulating triglycerides when compared with control fish, with no change in plasma concentrations of total protein. Plasma concentrations of androgen were similarly unaffected by cortisol treatment. In the short term (initial 1-2 wk), parental care of eggs and egg-sac fry was maintained by all groups, with no differences observed in behavior (e.g., tending, vigilance, defense) among the groups. However, the cortisol-treated fish abandoned their offspring at a higher rate than in the control or sham groups. The fish treated with cortisol also tended to develop external Saprolegnian infections, indicative of compromised immune function. These data demonstrate that exogenous cortisol elevation during parental care results in changes in energy use and a decrease in immune function. Interestingly, the data also suggest resistance to stress during parental care in largemouth bass, with no changes in parental care behavior before abandonment.
Cortisol in Correlation to Other Indicators of Fish Welfare
Chapter in Corticosteroids, IntechOpen , London, UK, 2018
Cortisol is the major corticosteroid in teleost fish, secreted and released by interrenal cells of the head kidney during activation of the hypothalamic-pituitary-interrenal (HPI) axis. Although cortisol is universally recognized as a key mediator of stress-associated responses, other hormones are also involved in the stress response, e.g., arginine vasoto-cin (AVT), isotocin (IT), urotensins, dopamine, serotonin or β-endorphin. Cortisol affects AVT and IT secretion from nerve endings in gilthead sea bream (Sparus aurata) and round goby (Neogobius melanostomus). Moreover, it is pointed out that different mechanisms are involved in the regulation of AVT and IT release from the hypothalamic-pituitary complex in round goby. In the case of AVT, both genomic and nongenomic pathways are mediating the effect of cortisol while in the case of IT, it is only the nongenomic pathway. In turn, urotensin I instead of corticotropin-releasing factor (CRF) may contribute to the regulation of HPI axis and regulate AVT in Sparus aurata. In this species, urotensin II together with AVT and IT may control stress response to different salinities. Therefore, AVT, IT and urotensins, and their interactions with cortisol, seem to be significant in response to stress in fish.
Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology, 2015
Cortisol is the main biomarker of physiological stress in fish. It is usually measured in plasma, which requires blood collection. Though cortisol is produced in the anterior kidney, it can diffuse easily through cell membranes due to its lipophilic nature. Taking advantage of that, some non-invasive techniques have been developed to measure cortisol directly in the water from fishholding tanks, in skin mucus or in scales. In this study, we explored the possibility to analyze fish cortisol from gill filaments as a reliable acute stress marker. Our results show that gill cortisol levels correlate well with plasma cortisol levels in both rainbow trout and zebrafish exposed or not to an acute stress protocol. Measuring cortisol in gill filaments increases the available possibilities for stress assessment in fish. Although this approach should yet be tested for its use with other stressors, it has several advantages: In relatively large fish (i.e. above 30 g) gill cortisol levels could be measured in vivo. Sampling of gill biopsies is very fast and easy, and the procedure does not induce stress if properly performed, making it an ideal option for in vivo stress assessment in the field. In small fish, the use of gill tissue to measure cortisol has important technical advantages with respect to the current methods using whole-body homogenates. Gill homogenates could be used directly for ELISA cortisol analysis, avoiding the need of tedious and expensive cortisol extraction protocols, and, since no organic solvent is required, contributing for a more environmentally friendly analysis.