Opercular Beat Rate Research Articles

Fin clipping does not increase opercular beat rate in tricaine-treated zebrafish.

To carry out research with genetically modified animals, their genotype has to be assessed. A standard protocol to obtain required tissue samples from zebrafish is finclipping. However, some studies reported considerable stress induced by this protocol. We therefore assessed ventilation as a read-out for stress in zebrafish that underwent finclipping during routine genotyping in our fish facility. Our analysis could not confirm a strong increase of ventilation as had been previously reported. Instead, handled zebrafish showed ventilation rates in the range of controls that remained in their holding tanks. Additionally, we detected a slight reduction of ventilation rates up to an hour after anaesthesia in zebrafish treated with tricaine only, suggesting a prolonged protecting effect by this anaesthetic.

Impact of Household Chemicals on the Ornamental Fish Poecilia sphenops (Valenciennes)

This study examined the impact of various household chemicals, such as Surf excel, hair dye, popular soap, fabric softener, shampoo, and coconut oil, on the ornamental fish Poecilia sphenops (Valenciennes in Cuvier and Valenciennes, 1846). Length-weight relationships, gonadosomatic and hepatosomatic indexes, oxygen consumption, and opercular beat rate were measured to assess the effects of the chemicals (10, 20, and 30 ppm) on the fish. Results showed that at higher concentrations of the chemicals, the fish exhibited increased breathing and signs of distress. The temperature of 28°C was found to be optimum for the growth of P. sphenops, while the lowest growth performance was shown at temperature 30°C. Fish ranged from 37 to 67 mm in total length and 1.10 to 3.10 g in body weight. The female to male sex ratio (4.9:1) deviated significantly from the unity (?²= 214.2, p<0.05). These findings indicate that the presence of such noxious chemicals are deleterious to natural populations of fish, and that the irresponsible discharge of sewage water into water bodies should be avoided.

Integrated behavioural, neurological, muscular and cardiorespiratory response in tambaqui, Colossoma macropomum anaesthetized with menthol

Menthol has been recommended for fish anaesthesia in recent studies. However, no observations of brain electrical activity, electromyography and electrocardiogram have been reported to date in in vivo experiments using menthol. In order to fill the gaps at the electrophysiological and behavioural levels, juveniles of tambaqui, Colossoma macropomum were used as live models and subjected to two experimental conditions: I - Behavioural assessment using menthol at 100 mg.L−1; II - Characterization of electroencephalography (EEG), electromyography (EMG), electrocardiography (ECG), and opercular beat rate (OBR) using menthol at 100 mg.L−1. The fish were assayed into three groups for all characterizations: (a) control; (b) ethanol (vehicle control); and (c) menthol at100 mg.L−1, nine animals per group were used for each marker, one fish being considered a replicate (n = 9) and used only once. On the EEG, it was observed that menthol induced decreased mean power in cerebral activity, indicating the deepening of the anaesthesia, showing that menthol led to reversible CNS depression, with the resumption of mean power after washout, devoid of seizures or any other observable alterations. The EMG showed a decreased skeletal muscle tone, with no excitability or muscle spasms. The ECG showed a reduced heart rate, however, menthol did not elicit important alterations during induction or recovery in the duration of the QRS complex (ventricular depolarization). For all records the sinus rhythm was maintained, menthol did not lead to deleterious QT interval (ventricular contraction) prolongation, and the RR interval (time between two successive QRS complexes) corroborated a reversible anaesthetic effect. OBR showed the maintenance of the ventilatory rate during induction and recovery, which indicates a reduced risk of causing severe hypoxia. Overall, the electrophysiological data reinforced the results observed in the behavioural assessment. The findings indicate that menthol proved to be an effective and safe anaesthetic for tambaqui juveniles, as it did not cause major changes in the pattern of tracings, and therefore, should be considered a standard chemical compound of plant origin for the purpose of full immobilization and general anaesthesia of C. macropomum.

Boldness Predicts Aggressiveness, Metabolism, and Activity in Black Rockfish Sebastes schlegelii

Animal personality refers to individual behavioral and physiological differences that are consistent over time and across context. Recently, the fish personality has gained increasing attention, especially from the perspective of aquaculture production. Here, we used an important aquaculture species, black rockfishSebastes schlegelii, as the target animal, and conducted a series of experiments to explore the relationships among fish boldness, aggressiveness, locomotor activity, opercular beat rate, standard metabolic rate, and cortisol level. Generally, the results showed that the boldness of black rockfish was significantly, positively correlated with fish aggressiveness, stressed locomotor activity, and standard metabolic rate, while was negatively correlated with stressed opercular beat rate. Bold fish had significantly higher aggressiveness, standard metabolic rate, and stressed locomotor activity but lower stressed opercular beat rate. However, there were no significant correlations between boldness and basal locomotor activity or between boldness and basal cortisol level. These results preliminarily constructed the behavioral and physiological spectrum of black rockfish in the context of fish personality and clearly indicated that the boldness could be used as a discrimination tool to predict fish aggressiveness and metabolic rate, which may have valuable applications for decreasing fish harmful aggression and increasing fish welfare in the aquaculture industry.

BEHAVIOURAL RESPONSES OF AFRICAN CATFISH ( Clarias gariepinus BURCHELL, 1822) JUVENILES EXPOSED TO ACUTE CONCENTRATIONS OF BUTACHLOR (HERBICIDE)

This study examined the behavioral changes induced by butachlor to the juveniles of Clarias gariepinus. The experiment consists of five treatments (0.6, 0.7, 0.8, 0.9 and 1.0 mg/l) and a control. Ten fishes were allotted in each test tank in duplicates. Observations on behavioral responses were made at 0, 12, 24, 48, 72 and 96 hours post-exposure. The opercular movement and tail fin beat rates were observed as counts per minute using a stopwatch. The behavioral patterns of the fish in the control group were normal, whereas in the exposed groups the fish tend to lose equilibrium and swim erratically with vigorous jerky movements. At the 12th and 24th hours the fish in the exposed groups showed hyper-active movement, but became hypoactive at the 48th hour. The mean values of the tail fin beat of the exposed groups were significantly higher (p<0.05) than that of the control at the 12th hour. At the 24th and 48th hour post-exposure the exposed groups showed significant (p<0.05) time-dependent decrease compared to the control. The tail fin beat became significantly higher (P<0.05) in the control group from 72nd hours onward. The decrease of tail fin beats at the 72nd and 96th hours were dose-dependent similar observations were also recorded in the opercular ventilation. At the 12th hour the opercular ventilation of the exposed fish was significantly higher (p<0.05) than the control whereas at the 24th and 48th hours, the opercular ventilation of the exposed groups showed a significant decrease (p<0.05) compared to the control.

When cooling is worse than warming: investigations into the thermal tolerance of an endemic reef fish, Boopsoidea inornata

Recent investigations suggest that global warming is likely to alter temperature regimes along the southeastern coastline of South Africa through the increased frequency of upwelling events. Identifying thermal thresholds is fundamental in predicting the response of marine ectotherms to rapidly changing ocean temperatures. The aim of this study was to determine the thermal tolerance of the endemic sparid Boopsoidea inornata. To achieve this, 20 wild fish were captured from near Noordhoek in Gqeberha (Port Elizabeth). The fish were exposed to laboratory-simulated upwelling and heat-plume conditions until sublethal endpoints were identified to estimate the critical lower (CTmin) and critical upper (CTmax) thermal limits, respectively. During the simulated cooling or heating events, the opercular beat (OB) rates were recorded, their sublethal endpoints (loss of equilibrium) were identified, and their CTmin and CTmax were estimated. Breakpoint analyses of the OB rates identified the lower and upper thermal stress limits to occur at an average of 9 °C and 25 °C, respectively. The CTmin was estimated to be 7.8 °C and the CTmax 30 °C. When compared with in situ temperatures, these limits suggest that B. inornata is susceptible to small reductions in the minimum temperature. Given that the frequency and magnitude of upwelling events are expected to increase in response to global warming, this may have significant consequences for this and other sympatric, resident species.

Geraniol and citronellol as alternative and safe phytoconstituents to induce immobilization and facilitate handling of fish

The efficacy of a product as an anaesthetic can be determined through combining behavioural assessment and the evaluation of selected electrophysiological markers, such as the electromyogram (EMG) and electrocardiogram (ECG) for muscle contraction power and cardiac function characterizations, respectively. This study aimed to evaluate the anaesthetic efficacy of geraniol (GRL) and citronellol (CTL) in tambaqui juveniles, Colossoma macropomum, through concentration-response trials, and their effects on behaviour and cardiorespiratory responses. Fish (24.78 ± 2.50 g) were assayed into two experimental groups: I – Behavioural Assessment: In which six concentrations were tested (10; 30; 50; 70; 90; and 110 μL L−1) for each compound. For both isolates the concentration of 10 μL L−1 did not induce any signs of anaesthesia. As for the other concentrations, all fish were anaesthetized and fully recovered according to behaviour evaluation. Concentrations of 70 μL L−1 GRL and 90 μL L−1 CTL were considered the most effective doses as they promoted anaesthesia and allowed for recovery within appropriate time intervals; II – Electrophysiological Characterization: Concentrations of 70 μL L−1 GRL and 90 μL L−1 CTL were used for the recordings of EMG, ECG, opercular beat intensity and rate (OBI and OBR), and heart rate (HR). For both experiments, nine fish per concentration (n = 9) per analysis were used and each animal was considered a replicate. Our results demonstrated that geraniol and citronelol induced full body immobilization, which resulted at least in part, from the myorelaxant properties of these compounds. GRL and CTL at 70 μL L−1 and 90 μL L−1, respectively were sufficient to render fish fully and rapidly immobilized. Both products transiently reduced ventilation during anaesthesia, nevertheless allowing for complete recovery after exposure. Although either isolate significantly decreased heart rates, they did not compromise resumption of normal cardiac function. In general, no mortalities were observed and all animals recovered after exposure. Both products could be considered safe alternatives for fish handling and other aquaculture-related activities that might require fish immobilization.

Condition-dependent responses of fish to motorboats.

Anthropogenic noise is a pollutant of global concern that has been shown to have a wide range of detrimental effects on multiple taxa. However, most noise studies to-date consider only overall population means, ignoring the potential for intraspecific variation in responses. Here, we used field experiments on Australia's Great Barrier Reef to assess condition-dependent responses of blue-green damselfish (Chromis viridis) to real motorboats. Despite finding no effect of motorboats on a physiological measure (opercular beat rate; OBR), we found a condition-dependent effect on anti-predator behaviour. In ambient conditions, startle responses to a looming stimulus were equivalent for relatively poor- and good-condition fish, but when motorboats were passing, poorer-condition fish startled at significantly shorter distances to the looming stimulus than better-condition fish. This greater susceptibility to motorboats in poorer-condition fish may be the result of generally more elevated stress levels, as poorer-condition fish had a higher pre-testing OBR than those in better condition. Considering intraspecific variation in responses is important to avoid misrepresenting potential effects of anthropogenic noise and to ensure the best management and mitigation of this pervasive pollutant.

Effect of environmental enrichment on the stress response of juvenile black rockfish Sebastes schlegelii

The stress response is one of the most important aspects of fish welfare in aquaculture. However, relatively few studies focusing on the effect of environmental enrichment on the fish stress response have been conducted, and their limited results were considerably contradictory. The present study aimed to investigate whether the enrichment type and amount had significant effects on the basal stress level and physiological and behavioral responses to acute stress of juvenile black rockfish Sebastes schlegelii. Fish were reared for eight weeks in environments with two enrichment types and three enrichment amounts (i.e., no environmental enrichment control (C), low-amount plant enrichment (PL), medium-amount plant enrichment (PM), high-amount plant enrichment (PH), low-amount structure enrichment (SL), medium-amount structure enrichment (SM), and high-amount structure enrichment (SH)), and subsequently, they were successively subjected to two common acute stressors (i.e., air exposure and confinement) and sampled at 0, 0.5, 1, 3 and 6 h after stress. In general, the plant enrichment groups experienced significantly higher basal stress (indicated by cortisol level and opercular beat rate) than the structure enrichment groups. Meanwhile, no enrichment control group and low-amount enrichment groups experienced significantly higher basal stress than the other two enrichment amount groups. After being subjected to acute stress, the peak cortisol levels of the high-amount enrichment groups were significantly higher than that of the other three enrichment amount groups. The PM, PH and SL fish recovered to basal stress levels at 1 h, the C and PL fish recovered at 3 h, and the SM and SH fish recovered at 6 h after the stress. Moreover, their basal cortisol levels showed strong correlations with peak cortisol levels and recovery time from stress. The correlation between cortisol level and opercular beat rate was also strong. Taken together, these results provide the first evidence to show that enrichment type and amount had significant effects on the fish stress response and might have important applications in fish husbandry and welfare. Based on these results, we suggest that it may be optimal for fish basal stress level and development of an adaptive capacity to provide a medium-amount (approximately 50% floor space coverage) of mixed enrichment in aquaculture.

Comparative Effects of Aqueous and Freeze Dried Leaf Extracts of <i>Tephrosia vogelii</i> on <i>Heterobranchus longifilis</i> Juveniles Val. (Pisces: 1840)

The present study was carried out to evaluate the potential of the aqueous leaf and freeze-dried leaf extracts of Tephrosia vogelii as tranquilizers on an African catfish, Hetetobranchus longifilis post juveniles (mean weight 115.00±25.00g) obtained from wild stock. They were acclimatized under laboratory conditions for two weeks prior to the commencement of the experiment. The fish were fed once a day at 9.00 hours at 4% body weight during the period of acclimatization. Each tank containing acclimatization water was aerated to enhance dissolved oxygen, and water was changed daily to prevent metabolic waste build up. Experimental fish were starved for 24 hours prior to sedation to prevent regurgitation from the gastro-intestinal tract (GIT). Four healthy Hetetobranchus longifilis were selected randomly from both the control and treatment groups. Each fish was weighted and injected 0.05ml of aqueous and freeze-dried leaf extracts at concentrations of 0.01, 0.02, 0.03, 0.04, 0.05 and 0.06g/l using №. 23 needle and a 2ml heparinized syringe. Injection was done intramuscularly (IM) at the dorsal saddle just above the lateral line behind the operculum. Fish in the control group were injected with distilled water. Injected fish were observed for behavioural responses. The result showed that H. longifilis injected with the freeze-dried leaf extract of T. vogelii passed sequentially through the first three stages of anaesthesia but could not attain total loss of equilibrium (stage 4 of anaesthsia). Behavioural responses included mucus secretion, slow and erratic swimming, excrement discharge, increase in opercular beat rate, strong retension of reflex action, partial loss of equilibrium and colour change. The induction time decreased with increasing concentration of the anaesthetic extract. The recovery time followed the reverse order. The opercular beat rates, before and after sedation in the treatment groups showed increase over that in the control group and it increased with increasing concentration. The result of the experiment with aqueous leaf extract showed that there was no significant difference in opercular beat rate after sedation in all centrations used (P>0.05). The result also showed that at higher concentration (0.06g/l) induction was time 44.67 seconds while at concentration 0.02g/l induction time was 83.70 seconds. In the case of the freeze-dried leaf extract of T. vogelii the induction at concentration 0.06g/l was 49.33 seconds while at concentration 0.02g/l induction time 76.67 seconds.

Propofol and essential oil of Nepeta cataria induce anaesthesia and marked myorelaxation in tambaqui Colossoma macropomum: Implications on cardiorespiratory responses

This study aimed at characterizing the modulation of skeletal muscle contraction and cardiorespiratory response of tambaqui, Colossoma macropomum submitted to baths using anaesthetic concentrations (capable of inducing fast, i.e. < 5 min, and full body immobilization) of propofol (PRP) and essential oil of Nepeta cataria (EON). For the evaluation of electromyography, electrocardiographic data, and opercular beat intensity (OBI) and rate (OBR), fish (5.6 ± 1.8 g, 8.0 ± 0.3 cm, total length) were assigned to the following groups: a) control (basal recording), b) ethanol-exposed fish (vehicle control), c) fish submitted to induction with EON at 175 μL L−1 and subsequent recovery, and d) fish submitted to induction with PRP at 4 μL L−1 and subsequent recovery. Eight fish (n = 8) per group were used. Both products induced full body immobilization and suppressed (99.9%) dorsal muscle contraction power, determining a general anaesthesia-like state. During exposure to either anaesthetic, cardiac function was transiently affected, with decreased heart rates (42–43%) and a mild arrhythmia in PRP recovering fish. Moreover, ventilatory capacity was reduced with this drug (85.3% and 59.6% decrease in OBI and OBR, respectively), yet without mortality. On the other hand, EON did not alter ECG tracings, allowing for the maintenance of normal ventilation intensity during exposure, albeit a slight increment in OBR occurred during deep anaesthesia. This study confirms propofol anaesthesia in fish and presents N. cataria essential oil as a novel and safe natural anaesthetic for juvenile Colossoma macropomum and potentially for other teleost species.

Physiological and behavioural evaluation of common anaesthesia practices in the rainbow trout

Anaesthetic drugs are commonly administered to fish in aquaculture, research and veterinary contexts. Anaesthesia causes temporary absence of consciousness and may reduce the stress and/or pain associated with handling and certain invasive procedures. The rainbow trout (Oncorhynchus mykiss) is a widely-used model species with relevance to both aquaculture and natural ecosystems. This study sought to establish the relative acute impact of commonly used anaesthetics on rainbow trout when used for anaesthesia or euthanasia by exploring their effects on aversion behaviour and stress physiology. Five widely used anaesthetics were investigated at two concentrations reflective of common laboratory practises: MS-222, benzocaine, 2-phenoxyethanol, etomidate and eugenol. The anaesthetics were administered via immersion and fish were: 1) euthanised with anaesthetic; or 2) allowed to recover from deep plane anaesthesia; or 3) subjected to a conditioned place avoidance paradigm. Behaviour, opercular beat rate and plasma cortisol concentrations and cortisol release rates to water were quantified to investigate the effects of the five drugs. Based upon longer induction to deep plane anaesthesia, and increased plasma cortisol levels post-anaesthesia the widely-used and recommended anaesthetic MS-222 may be relatively stressful for rainbow trout. Whereas 2-phenoxyethanol, due to a combination of quicker induction, reduced aversive behavioural response during anaesthesia and lower post-anaesthesia plasma cortisol levels may be a more advisable alternative. It is crucial for the welfare of fish that the use of anaesthetics is as humane as possible and thus these findings have important implications for the welfare and husbandry of captive rainbow trout.

Essential oil of citronella modulates electrophysiological responses in tambaqui Colossoma macropomum: A new anaesthetic for use in fish

The aim of this study was to evaluate the efficacy of essential oil of citronella, Cymbopogon nardus (EOC) as an anaesthetic for fish, using juvenile tambaqui Colossoma macropomum as a model. The times to induction and recovery after short-term anaesthesia were evaluated by concentration-response trials. Moreover, electrophysiological responses in muscle (EMG), electrocardiographic data (ECG), opercular beat intensity (OBI) and rate (OBR) were also evaluated. Juveniles were placed in aquaria containing six concentrations of EOC (200, 400, 600, 800, 1000 and 1600μLL−1) and the times of anaesthetic induction and recovery were registered. Sham control fish and fish exposed to ethanol-added water were used as controls. With the exception of the lowest concentration used (200μLL−1), deep anaesthesia was attained at all other subsequent concentrations, being the use of 600μLL−1 sufficient to promote rapid induction (<3min) and uneventful recovery (<5min) from deep anaesthesia; while the concentration of 200μLL−1 was sufficient to induce sedation. EOC elicited a conspicuous depression on muscle contraction power with loss of muscle tonus. Although transient cardiorespiratory depression occurred during deep anaesthesia, gradual increases in the amplitudes of the differences in potential and frequencies in EMG, OBI and ECG, corroborate the reversibility and smooth transition to normal swimming behaviour during recovery from anaesthesia with EOC.

EFFECTIVENESS OF THE ANESTHETIC AQUI-S® 20E IN MARINE FINFISH AND ELASMOBRANCHS.

Immersion anesthetics are used in hatchery settings by veterinarians, field biologists, and laboratory researchers to aid in handling finfish for medical procedures, research purposes, and moderating perceived stress responses. The only Food and Drug Administration- (FDA) approved anesthetic for food fish, tricaine methanesulfonate, requires a 21-d withdrawal period prior to harvest. Ten percent eugenol (AQUI-S® 20E) has been gaining momentum for FDA approval because of its 0-d withdrawal time if fish are not of harvestable size within 72 h of exposure. We performed two trials to determine appropriate anesthetic doses for two cultured marine finfish: Atractoscion nobilis (white seabass, WSB) and Seriola lalandi (California yellowtail, YT). Fish were held in a treated water bath for 10 min or until opercular beat rate slowed to a rate of <2 beats/min. Based on these results, we conducted a field trial with wild Paralabrax maculatofasciatus (spotted bay bass), Paralabrax nebulifer (barred sand bass), Paralichthys californicus (California halibut), Triakis semifasciata (leopard shark), and Mustelus californicus (grey smooth-hound) at a single dosing regime, with animals held 5-10 min in anesthetic baths. Anesthetic dosing of 35-55 mg L(-1) provided relatively fast induction and good anesthetic maintenance in cultured and wild finfish. Anesthetic induction times were comparable among S. lalandi and A. nobilis at 35-mg L(-1) to 75-mg L(-1) doses, but recovery times were variable. Mortality rates of 20-90% were observed at higher doses (75 mg L(-1) and 100 mg L(-1), A. nobilis; 55 mg L(-1) and 75 mg L(-1), S. lalandi). The apparent increase in sensitivity of S. lalandi may have been associated with nutritional stress in the fish tested. There were no differences in time to anesthesia or recovery among wild finfish species tested at a single dose. Anesthetic induction, maintenance, and recovery were less predictable in the elasmobranch species tested and additional trials are needed to determine optimal dosing.

Does environmental enrichment promote recovery from stress in rainbow trout?

The EU Directive on animal experimentation suggests that all protected animals should have enrichment to improve welfare yet relatively little research has been conducted on the impact of enrichment in fish. Studies employing enrichment in zebrafish have been contradictory and all fish species should be provided with species-specific enrichments relevant to their ecology. Salmonids are important experimental models in studies within aquaculture, toxicology and natural ecosystems. This study therefore sought to establish whether an enriched environment in an experimental aquarium may promote improved welfare in rainbow trout (Oncorhynchus mykiss) by enhancing their recovery from invasive procedures. Trout were held individually in either barren (no tank ornamentation) or enriched (gravel, plants and an area of cover) conditions. Recovery rates after a noxious stimulus and a standard stressor were investigated by monitoring behaviour, opercular beat rate and plasma cortisol concentrations. Fish were randomly assigned to one of four treatment groups: Control (undisturbed), Sham (handled but not manipulated), Stress (air emersion) and Pain (subcutaneous injection of acetic acid). The results suggest that for rainbow trout environmental enrichment appears to promote recovery and ameliorate adverse effects following a stressor. However, recovery rate did not differ between environments in the pain treatment groups. Thus environmental enrichment may not be an important factor when the fish is responding to a painful stimulus. These results have important implications for the husbandry and welfare of captive rainbow trout and possibly other salmonids and suggest that enriched environments may be preferable to barren environments in experimental studies.

Physiological and behavioural responses to noxious stimuli in the Atlantic cod (Gadus morhua).

In the present study, our aim was to compare physiological and behavioural responses to different noxious stimuli to those of a standardized innocuous stimulus, to possibly identify aversive responses indicative of injury detection in a commercially important marine teleost fish, the Atlantic cod. Individual fish were administered with a noxious stimulus to the lip under short-term general anaesthesia (MS-222). The noxious treatments included injection of 0.1% or 2% acetic acid, 0.005% or 0.1% capsaicin, or piercing the lip with a commercial fishing hook. Counts of opercular beat rate (OBR) at 10, 30, 60, 90 and 120 min and observations of behaviour at 30 and 90 min post-treatment were compared with pre-treatment values and with control fish injected with physiological saline, an innocuous stimulus. Circulatory levels of physiological stress indicators were determined in all fish at 120 minutes post-treatment. All treatments evoked temporarily increased OBR that returned to pre-treatment levels at 60 minutes (saline, 0.005% capsaicin, hook), 90 minutes (0.1% acetic acid, 0.1% capsaicin), or 120 minutes (2% acetic acid), but with no significant differences from the control group at any time point. Fish treated with 0.1% and 2% acetic acid and 0.1% capsaicin displayed increased hovering close to the bottom of the aquaria and fish given 2% acetic acid and 0.1% capsaicin also displayed a reduced use of shelter. The only effect seen in hooked fish was brief episodes of lateral head shaking which were not seen pre-treatment or in the other groups, possibly reflecting a resiliency to tissue damage in the mouth area related to the tough nature of the Atlantic cod diet. There were no differences between groups in circulatory stress indicators two hours after treatment. This study provides novel data on behavioural indicators that could be used to assess potentially aversive events in Atlantic cod.

Ventilatory responses to skin extract in catfish

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 15:205-214 (2012) - DOI: https://doi.org/10.3354/ab00429 Ventilatory responses to skin extract in catfish Rodrigo Egydio Barreto1,*, Augusto Barbosa Júnior2, Anette Hoffmann2 1Departamento de Fisiologia, Instituto de Biociências, Caunesp, UNESP, Rubião Jr. s/n, Botucatu, São Paulo 18618-970, Brazil 2Laboratório de Neurofisiologia Comparada, Departamento de Fisiologia, Faculdade de Medicina de Ribeirão Preto, USP, Av. Bandeirantes 3900, Monte Alegre, Ribeirão Preto, São Paulo 14049-900, Brazil *Email: rebarreto@yahoo.com ABSTRACT: The ventilation rate (VR) of an ostariophysan fish, the speckled catfish Pseudoplatystoma coruscans, exposed to a chemical alarm cue was measured in the present study in multiple contexts. The influence of the extraction techniques, skin donor food intake and quantity of the alarm cue (skin extract) on this autonomic response was considered. Overall, the catfish VR decreased significantly when exposed to the skin extract (chemical alarm cue) compared with exposure to distilled water (control). No effect of the extraction technique was found. Increasing doses of the skin extract induced a VR reduction of similar magnitude. However, extract obtained from daily-fed fish induced a significant decrease in the VR, whereas extract obtained from food-restricted fish did not induce any change in the VR. Thus, food intake was associated with the production of a more easily recognizable alarm cue in the speckled catfish. Interestingly, this effect was not related to differences in the number of club cells in the donor catfish epidermis. Dashing, or rapid swimming, a normal component of the alarm response in fish, including this catfish species, was not observed here, and hypoventilation was always associated with no swimming reaction. Together, these results suggest that hypoventilation is a reaction to a chemical alarm cue, likely resulting in improved crypsis, causing the fish to become less easily perceived by a potential predator that usually strikes prey in response to movement. KEY WORDS: Stress · Antipredator behavior · Chemical communication · Alarm substance · Neurovegetative system · Opercular beat rate Full text in pdf format PreviousNextCite this article as: Barreto RE, Barbosa Júnior A, Hoffmann A (2012) Ventilatory responses to skin extract in catfish. Aquat Biol 15:205-214. https://doi.org/10.3354/ab00429 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 15, No. 3. Online publication date: June 06, 2012 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2012 Inter-Research.

Eficácia do eugenol extraído da planta Eugenia aromática como anestésico para realização de biometrias em adultos de tilápia do Nilo (Oreochromis niloticus)

Efficacy of eugenol extracted from the plant Eugenia aromatica as an anesthetic for the biometry procedures in Nile tilapia (Oreochromis niloticus) adults. Anesthetics represent a powerful tool in aquaculture, working to reduce stress and mortality commonly caused by handling. The objective this work was evaluate the effect of various concentrations of eugenol in adults of Nile tilapia and determine its optimal concentration for biometry procedures. Six concentrations (30, 60, 120, 180, 240 e 300 mg L -1 ) were tested. For each treatment, 12 fishes (average length: 32.7 ± 3.0; average weight: 557.0 ± 160 g) were individually immersed in anesthetic solution for 10 min. All stages of anesthesia were monitored during anesthetic induction, and upon profound anesthesia the opercular beat rate was monitored for the next minute. After anesthetic induction, the fishes were transferred to an aquarium containing water without anesthetic solution, and recovery time was measured. The 60 mg L -1 concentration required more time to reach the desired stage of profound anesthesia (206.3 seconds), while the 300 g L -1 concentration reached this stage more rapidly (77.8 seconds). Results suggest that the optimal concentration of eugenol for biometry procedures is 120 mg L -1 ,

Behavioural response of juvenile Chinook salmon Oncorhynchus tshawytscha during a sudden temperature increase and implications for survival

· Juvenile Chinook salmon Oncorhynchus tshawytscha survival and behaviour were evaluated during a temperature increase from 8.8 to 23.2 °C. · Relatively little mortality (12%) occurred, which was unexpected. · The percent of fish with an active swimming behaviour increased from 26% to 93% and opercular beat rates increased from 76 to 159 beats per minute. · Although sublethal in the laboratory, thermal stress was likely incurred by juvenile salmon in this study and the associated behavioural changes may increase predation potential in the wild.

Variable stress-responsiveness in wild type and domesticated fighting fish

VERBEEK, P., T. IWAMOTO AND N. MURAKAMI. Variable stress-responsiveness in wild type and domesticated fighting fish. PHYSIOL BEHAV XX(X) 000-000, 2007. We combined behavioral and physiological measures to compare coping style in wild-type Betta splendens and a domesticated strain selectively bred for sports fighting. We showed previously that the fighter strain is more aggressive than the wild type during experimental conditions that most closely resemble an actual fight. We predicted that compared to the wild type, the fighter strain would show a more proactive coping style, characterized by lesser cortisol and greater sympathetic responses to non-social challenges. We introduced males to an unfamiliar environment and spatial confinement as challenges that may resemble some of those that B. splendens may encounter in its natural habitat. We developed a non-invasive stress assay that enables repeated individual measures of water-borne cortisol. We estimated sympathetic activation through opercular beat rate and recorded the duration of behavioral immobility. We found that exposure to an unfamiliar environment raised cortisol levels in the wild type but not in the fighter strain and that confinement raised cortisol levels in both. In both strains opercular beat rates were significantly reduced during the latter stages of confinement compared to during the early stages. The fighter strain, but not the wild type, adopted a behavioral strategy of immobility from the very beginning of confinement.