In a marine teleost, the significance of oxygen supply for acute thermal tolerance depends upon the context and the endpoint used.

Eight juvenile European seabass were exposed to two thermal ramping protocols with different levels of aerobic activity and tolerance endpoint: the critical thermal maximum for swimming (CTSmax) while exercising aerobically until fatigue and the critical thermal maximum (CTmax) under static conditions until loss of equilibrium (LOE). In the CTSmax protocol, warming caused a profound increase in the rate of oxygen uptake (ṀO2), culminating in a gait transition from steady aerobic towards unsteady anaerobic swimming, then fatigue at 30.3±0.

Tolerance of an acute warming challenge declines with body mass in Nile tilapia: evidence of a link to capacity for oxygen uptake.

It has been proposed that larger individuals within fish species may be more sensitive to global warming, as a result of limitations in their capacity to provide oxygen for aerobic metabolic activities. This could affect size distributions of populations in a warmer world but evidence is lacking. In Nile tilapia Oreochromis niloticus (n=18, mass range 21-313 g), capacity to provide oxygen for aerobic activities (aerobic scope) was independent of mass at an acclimation temperature of 26°C.

An investigation of links between metabolic rate and feed efficiency in European sea bass Dicentrarchus labrax.

Feed efficiency (FE) is the amount of body weight gain for a given feed intake. Improving FE through selective breeding is key for sustainable finfish aquaculture but its evaluation at individual level is technically challenging. We therefore investigated whether individual routine metabolic rate (RMR) was a predictor of individual FE in the European sea bass Dicentrarchus labrax, a major species in European mariculture.

Intraspecific variation in tolerance of warming in fishes.

Intraspecific variation in key traits such as tolerance of warming can have profound effects on ecological and evolutionary processes, notably responses to climate change. The empirical evidence for three primary elements of intraspecific variation in tolerance of warming in fishes is reviewed. The first is purely mechanistic that tolerance varies across life stages and as fishes become mature.

Using aerobic exercise to evaluate sub-lethal tolerance of acute warming in fishes.

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 (CT) protocol. Two species were studied, Nile tilapia () and pacu (). Each fish underwent an incremental swim test to determine gait transition speed (), where it first engaged the unsteady anaerobic swimming mode that preceded fatigue.

Physiological determinants of individual variation in sensitivity to an organophosphate pesticide in Nile tilapia Oreochromis niloticus.

Individual variation in sub-lethal sensitivity to the organophosphate pesticide trichlorfon was investigated in Nile tilapia, using critical swimming speed (U) as an indicator. Tilapia exposed for 96h to 500μgl trichlorfon at 26°C (Tcfn group, n=27) showed a significant decline in mean U, compared to their own control (pre-exposure) performance in clean water (-14.5±2.

The role of the autonomic nervous system in control of cardiac and air-breathing responses to sustained aerobic exercise in the African sharptooth catfish Clarias gariepinus.

Clarias gariepinus is a facultative air-breathing catfish that exhibits changes in heart rate (ƒ) 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~20cm), and how exercise influenced variations in f associated with AB.

Severe hypoxia impairs lateralization in a marine teleost fish.

In intertidal environments, the recurring hypoxic condition at low tide is one of the main factors affecting fish behaviour, causing broad effects on ecological interactions. We assessed the effects of hypoxia on lateralization (e.g.