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| Blasco, Felipe R.; Mckenzie, David J.; Taylor, Edwin W.; Rantin, F. Tadeu. |
| Clarias gariepinus is a facultative air-breathing catfish that exhibits changes in heart rate (f(H)) associated with air breaths (AB). A transient bradycardia prior to the AB is followed by sustained tachycardia during breath-hold. This study evaluated air-breathing and cardiac responses to sustained aerobic exercise in juveniles (total length similar to 20 cm), and how exercise influenced variations in f(H) associated with AB. In particular, it investigated the role of adrenergic and cholinergic control in cardiac responses, and effects of pharmacological abolition of this control on air-breathing responses. Sustained exercise at 15, 30 and 45 cm s(-1) in a swim tunnel caused significant increases in f(AB) and f(H), from approximately 5 breaths h(-1) and... |
| Tipo: Text |
Palavras-chave: Adrenergic tone; Cholinergic tone; Heart rate; Swimming. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00367/47821/74728.pdf |
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| Lefevre, Sjannie; Mckenzie, David J.; Nilsson, Goran E.. |
| Some recent modelling papers projecting smaller fish sizes and catches in a warmer future are based on erroneous assumptions regarding (i) the scaling of gills with body mass and (ii) the energetic cost of 'maintenance'. Assumption (i) posits that insurmountable geometric constraints prevent respiratory surface areas from growing as fast as body volume. It is argued that these constraints explain allometric scaling of energy metabolism, whereby larger fishes have relatively lower mass-specific metabolic rates. Assumption (ii) concludes that when fishes reach a certain size, basal oxygen demands will not be met, because of assumption (i). We here demonstrate unequivocally, by applying accepted physiological principles with reference to the existing... |
| Tipo: Text |
Palavras-chave: Aerobic scope; Gill surface area; Growth; Metabolism; Oxygen consumption; Respiration; Scaling. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00395/50621/51449.pdf |
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| Killen, Shaun S.; Esbaugh, Andrew J.; Martins, Nicolas F.; Rantin, F. Tadeu; Mckenzie, David J.. |
| 1. Group-living is widespread among animals and comes with numerous costs and benefits. To date, research examining group-living has focused on trade-offs surrounding foraging, while other forms of resource acquisition have been largely overlooked. 2. Air-breathing has evolved in many fish lineages, allowing animals to obtain oxygen in hypoxic aquatic environments. Breathing air increases the threat of predation, so some species perform group air-breathing, to reduce individual risk. Within species, individual air-breathing can be influenced by metabolic rate as well as personality, but the mechanisms of group air-breathing remain unexplored. It is conceivable that keystone individuals with high metabolic demand or intrinsic tendency to breathe air may... |
| Tipo: Text |
Palavras-chave: Air-breathing fish; Ecophysiology; Group-living; Keystone individuals; Metabolic rate; Social behaviour. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00417/52831/78979.pdf |
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