Glycogen depletion in juvenile rainbow trout as an experimental test of the oxygen debt hypothesis

232

238

test temperature. The non-aerobic cost of swimming to Ucrit was estimated to add an additional 21.4-50.5% to the oxygen consumption measured at U crit. While these nonaerobic contributions to swimming did not affect the minimum cost of transport, they were up to three times higher than the value used previously for an energetic model of salmon migration in the Fraser River, BC, Canada. As such, the underestimate of non-aerobic swimming costs may require a reevaluation of the importance of how in-river barriers like rapids and bypass facilities at dams, and year-to-year changes in river flows and temperatures, affect energy use and hence migration success.

Section: Discussionmentioning

confidence: 87%

Section: Exercise Protocolsmentioning

confidence: 99%

mentioning

confidence: 99%

See 1 more Smart Citation

Excess post-exercise oxygen consumption in adult sockeye(Oncorhynchus nerka) and coho (O. kisutch) salmon following critical speed swimming

Lee

Farrell

Lotto

et al. 2003

232

238

“…In contrast, recovery time without a warm-down is >2·h for optimal performance on a time-to-exhaustion test (Mitton and McDonald, 1994). Wang et al (1994) reported that muscle phosphocreatine and ATP levels were restored within 30·min of rainbow trout being chased to exhaustion, while the post-exercise decline of oxygen consumption lasted 3-3.5·h (Scarabello et al, 1991). However, routine oxygen consumption does not have to be restored before adult sockeye salmon can repeat a second Ucrit test (Farrell et al, , 2003.…”

Section: Discussionmentioning

confidence: 99%

Influence of seasonal temperature on the repeat swimming performance of rainbow troutOncorhynchus mykiss

Jain

Farrell

2003

157

116

). Given that metabolic recovery in skeletal muscle (muscle lactate, ATP and glycogen, but not PCr) occurs more rapidly at warm than cold temperatures in exhausted rainbow trout Oncorhynchus mykiss and Atlantic salmon Salmo salar (Kieffer et al., 1994;Wilkie et al., 1997;Kieffer, 2000), the expectation is that swimming performance is restored faster at a higher temperature. This expectation would be consistent with the known increase in both maximum oxygen uptake and maximum cardiac output with temperature (e.g. Butler et al., 1992;Farrell, 1997;Taylor et al., 1997) because an improved oxygen delivery system could support a more rapid recovery of the metabolic debt incurred with exhaustive exercise. However, when Atlantic salmon were angled rather than chased to exhaustion, muscle glycogen, intracellular pH and lactate were restored more rapidly under cold conditions than warm conditions (Wilkie et al., While the temperature dependence of exercise performance in fishes is reasonably well documented, information on the temperature dependence of metabolic recovery and reperformance is scant. This study examined the recovery of swimming performance after exhaustive exercise in rainbow trout Oncorhynchus mykiss at seasonal temperatures ranging from 5 to 17°C and explored the relationship between performance and preceding metabolic state. The primary objective of the study was to test the hypothesis that increased temperature increases the capability of rainbow trout to repeat a critical swimming speed (U crit), as assessed by two consecutive critical swimming speed tests separated by a 40·min rest interval. An additional expectation was that certain plasma ionic, metabolic and humoral parameters would be correlated with how well fish reperformed and so plasma levels of lactate, potassium, ammonia, osmolality, sodium and cortisol, as well as hematocrit, were monitored before, during and after the swim challenges via an indwelling cannula in the dorsal aorta. As expected, performance in the first Ucrit test (Ucrit1) was positively related to temperature. However, the relationship between Ucrit1 and reperformance (Ucrit2) was not dependent on acclimation temperature in a simple manner. Contrary to our expectations, Ucrit2 was less than Ucrit1 for warmacclimated fish (14.9±1.0°C), whereas Ucrit2 equaled Ucrit1 for cold-acclimated fish (8.4±0.9°C). Cold-acclimated fish also exhibited a lower Ucrit1 and less metabolic disruption compared with warm-acclimated fish. Thus, while warm acclimation conferred a faster Ucrit1, a similar swimming speed could not be attained on subsequent swim after a 40·min recovery period. This finding does not support the hypothesis that the ability of rainbow trout to reperform on U crit test is improved with temperature. Both plasma lactate and plasma potassium levels were strongly correlated with Ucrit1 performance. Therefore, the higher Ucrit1 of warm-acclimated fish may have been due in part to a greater anaerobic swimming effort compared with cold-acclimated fish. In fact, a significant co...

“…1). To deconvolute these signals, the first phase of the metabolic response was modelled using Eqn 2 (Scarabello et al, 1991):…”

Section: -2016042515065062 V2)mentioning

confidence: 99%

An early-life hypoxia event has a long-term impact on protein digestion and growth in European sea bass juvenile

Zambonino-Infante

Mazurais

Servili

et al. 2017

Ocean warming, eutrophication and the consequent decrease in oxygen lead to smaller average fish size. Although such responses are well known in an evolutionary context, involving multiple generations, this appears to be incompatible with current rapid environmental change. Instead, phenotypic plasticity could provide a means for marine fish to cope with rapid environmental changes. However, little is known about the mechanisms underlying plastic responses to environmental conditions that favour small phenotypes. Our aim was to investigate how and why European sea bass that had experienced a short episode of moderate hypoxia during their larval stage subsequently exhibited a growth depression at the juvenile stage compared with the control group. We examined whether energy was used to cover higher costs for maintenance, digestion or activity metabolisms, as a result of differing metabolic rate. The lower growth was not a consequence of lower food intake. We measured several respirometry parameters and we only found a higher specific dynamic action (SDA) duration and lower SDA amplitude in a fish phenotype with lower growth; this phenotype was also associated with a lower protein digestive capacity in the intestine. Our results contribute to the understanding of the observed decrease in growth in response to climate change. They demonstrate that the reduced growth of juvenile fishes as a consequence of an early life hypoxia event was not due to a change of fish aerobic scope but to a specific change in the efficiency of protein digestive functions. The question remains of whether this effect is epigenetic and could be reversible in the offspring.