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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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| Mckenzie, David; Blasco, Felipe R.; Belao, Thiago C.; Killen, Shaun S.; Martins, Nathan D.; Taylor, Edwin W.; Tadeu Rantin, F.. |
| Individual variation in sub-lethal sensitivity to the organophosphate pesticide trichlorfon was investigated in Nile tilapia, using critical swimming speed (U-crit) as an indicator. Tilapia exposed for 96 h to 500 mu g l-1 trichlorfon at 26 degrees C (Tcfn group, n = 27) showed a significant decline in mean U-crit, compared to their own control (pre-exposure) performance in clean water (-14.5 +/- 2.3%, mean +/- SEM), but also compared to a Sham group (n = 10) maintained for 96 h in clean water. Individuals varied in their relative sensitivity to the pesticide, with the decline in U-crit after exposure varying from 1 to 41%. The U-crit of the Tcfn group did not recover completely after 96 h in clean water, remaining 9.4 +/- 3.2% below their own control... |
| Tipo: Text |
Palavras-chave: Trichlorfon; Critical swimming speed; Metabolic rate; Respirometry; Nile tilapia; Individual variation. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00625/73705/74889.pdf |
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| Blasco, Felipe R.; Esbaugh, Andrew J.; Killen, Shaun S.; Rantin, Francisco Tadeu; Taylor, Edwin W.; Mckenzie, David. |
| We investigated whether fatigue from sustained aerobic swimming provides a sub-lethal endpoint to define tolerance of acute warming in fishes, as an alternative to loss of equilibrium (LOE) during a critical thermal maximum (CTmax) protocol. Two species were studied, Nile tilapia (Oreochromis niloticus) and pacu (Piaractus mesopotamicus). Each fish underwent an incremental swim test to determine gait transition speed (U-GT), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue. After suitable recovery, each fish was exercised at 85% of their own U-GT and warmed 1 degrees C every 30 min, to identify the temperature at which they fatigued, denoted as CTswim. Fish were also submitted to a standard CTmax, warming at the same rate... |
| Tipo: Text |
Palavras-chave: CTmax; Oreochromis niloticus; Piaractus mesopotamicus. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00640/75188/75324.pdf |
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