Effects of acclimation to brackish water on the growth, respiratory metabolism, and swimming performance of young-of-the-year Adriatic sturgeon (<i>Acipenser naccarii</i>)

SUMMARYEuropean eels were exposed for 6 weeks to water CO2 partial pressures (PCO2) from ambient (approx. 0.8 mmHg), through 15±1 mmHg and 30±1 mmHg to 45±1 mmHg in water with a total hardness of 240 mg l–1 as CaCO3, pH 8.2, at 23±1°C. Arterial plasma PCO2 equilibrated at approximately 2 mmHg above water PCO2 in all groups, and plasma bicarbonate accumulated up to 72 mmol l–1 in the group at a water PCO2 of 45 mmHg. This was associated with an equimolar loss of plasma Cl–, which declined to 71 mmol l–1 at the highest water PCO2. Despite this, extracellular acid–base compensation was incomplete; all hypercapnic groups tolerated chronic extracellular acidoses and reductions in arterial blood O2 content (CaO2), of progressive severity with increasing PCO2. All hypercapnic eels, however, regulated the intracellular pH of heart and white muscle to the same levels as normocapnic animals. Hypercapnia had no effect on such indicators of stress as plasma catecholamine or cortisol levels, plasma osmolality or standard metabolic rate. Furthermore, although CaO2 was reduced by approximately 50% at the highest PCO2, there was no effect of hypercapnia on the eels' tolerance of hypoxia, aerobic metabolic scope or sustained swimming performance. The results indicate that, at the levels tested, chronic hypercapnia was not a physiological stress for the eel, which can tolerate extracellular acidosis and extremely low Cl–levels while compensating tissue intracellular pH, and which can meet the O2 requirements of routine and active metabolism despite profound hypoxaemia.

Section: Methodsmentioning

confidence: 99%

Section: Sustained Aerobic Exercise Performancementioning

confidence: 99%

Tolerance of chronic hypercapnia by the European eelAnguilla anguilla

McKenzie

Piccolella

Valle

et al. 2003

“…Fish oxygen uptake (M O2 ) and swimming performance were measured in a 49l modified Brett-type swim-tunnel respirometer (for details, see McKenzie et al, 2001) thermoregulated at 23±0.5°C. Briefly, the working section of the tunnel was 60cm in length, 16cm in width and 16cm in height.…”

Section: Experimental Set-upmentioning

confidence: 99%

Individual variation and repeatability in aerobic and anaerobic swimming performance of European sea bass,Dicentrarchus labrax

Marras

Claireaux

McKenzie

et al. 2010

132

120

SUMMARYStudies of inter-individual variation in fish swimming performance may provide insight into how selection has influenced diversity in phenotypic traits. We investigated individual variation and short-term repeatability of individual swimming performance by wild European sea bass in a constant acceleration test (CAT). Fish were challenged with four consecutive CATs with 5min rest between trials. We measured maximum anaerobic speed at exhaustion (U CAT ), gait transition speed from steady aerobic to unsteady anaerobic swimming (U gt ), routine metabolic rate (RMR), post-CAT maximum metabolic rate (MMR), aerobic scope and recovery time from the CATs. Fish achieved significantly higher speeds during the first CAT (U CAT 170cms -1 ), and had much more inter-individual variation in performance (coefficient of variation, CV18.43%) than in the subsequent three tests (U CAT 134cms -1 ; CV7.3%), which were very repeatable among individuals. The individual variation in U CAT in the first trial could be accounted for almost exclusively by variation in anaerobic burst-and-coast performance beyond U gt . The U gt itself varied substantially between individuals (CV11.4%), but was significantly repeatable across all four trials. Individual RMR and MMR varied considerably, but the rank order of post-CAT MMR was highly repeatable. Recovery rate from the four CATs was highly variable and correlated positively with the first U CAT (longer recovery for higher speeds) but negatively with RMR and aerobic scope (shorter recovery for higher RMR and aerobic scope). This large variation in individual performance coupled with the strong correlations between some of the studied variables may reflect divergent selection favouring alternative strategies for foraging and avoiding predation.

“…The U crit swimming tests were performed using two Bretttype swim-tunnel respirometers, designed to exercise individual fish in a non-turbulent water flow with a uniform velocity profile (Steffensen et al, 1984). One respirometer constructed of PVC has been described in detail previously (McKenzie et al, 2001). The second was of a similar design and size, but constructed in stainless steel, with a total water volume of 48·l and a swim chamber with a square crosssectional area of 290·cm 2 .…”

Section: Fish Holding and Screeningmentioning

confidence: 99%

“…Fish were considered to be fatigued when they were unable to remove themselves from the posterior screen of the swimming chamber despite gentle encouragement with a sudden increase in water velocity. Measurements of oxygen uptake (M O ∑) were collected at each swimming speed, as described in McKenzie et al (2001). These measurements were used to derive: (i) the notional metabolic rate of the immobile fish (IMR); (ii) the maximum metabolic rate of activity (AMR) during swimming (this occurred at speeds approaching U crit ); and (iii) net aerobic scope relative to IMR (McKenzie et al, 2003a).…”

Section: Fish Holding and Screeningmentioning

confidence: 99%

Linking swimming performance, cardiac pumping ability and cardiac anatomy in rainbow trout

Claireaux¹,

McKenzie²,

Genge

et al. 2005

181

152

vs 5.79±1.97·mW·g-1 , respectively). Cardiac morphology was visualised in vivo by Doppler echography on anaesthetised individual fish and revealed that poor swimmers had a significantly more rounded ventricle (reduced ventricle length to height ratio) compared with good swimmers, which in turn was correlated with fish condition factor. These results provide clear evidence that maximum cardiac performance is linked to AMR and U crit and indicate that a simple screening test can distinguish between rainbow trout with lower active metabolic rate, U crit , maximal cardiac pumping capacity and a more rounded ventricular morphology. These distinguishing traits may have been retained for 9 months despite a common growing environment and growth.