Physiological mechanisms underlying a trade-off between growth rate and tolerance of feed deprivation in the European sea bass (Dicentrarchus labrax)

Abstract

The specific growth rate (SGR) of a cohort of 2000 tagged juvenile European sea bass was measured in a common tank, during two sequential cycles comprising three-weeks feed deprivation followed by three-weeks ad libitum re-feeding. After correction for initial size at age as fork length, there was a direct correlation between negative SGR (rate of mass loss) during feed deprivation and positive SGR (rate of compensatory growth) during re-feeding (Spearman rank correlation R=0.388, P=0.000002). Following a period of rearing under standard culture conditions, individuals representing 'high growth' phenotypes (GP) and 'high tolerance of feed deprivation' phenotypes (DP) were selected from either end of the SGR spectrum. Static and swimming respirometry could not demonstrate lower routine or standard metabolic rate in DP to account for greater tolerance of feed deprivation. Increased rates of compensatory growth in GP were not linked to greater maximum metabolic rate, aerobic metabolic scope or maximum cardiac performance than DP. When fed a standard ration, however, GP completed the specific dynamic action (SDA) response significantly faster than DP. Therefore, higher growth rate in GP was linked to greater capacity to process food. There was no difference in SDA coefficient, an indicator of energetic efficiency. The results indicate that individual variation in growth rate in sea bass reflects, in part, a trade-off against tolerance of food deprivation. The two phenotypes represented the opposing ends of a spectrum. The GP aims to exploit available resources and grow as rapidly as possible but at a cost of physiological and/or behavioural attributes, which lead to increased energy dissipation when food is not available. An opposing strategy, exemplified by DP, is less 'boom and bust', with a lower physiological capacity to exploit resources but which is less costly to sustain during periods of food deprivation.

Low O2 acclimation shifts the hypoxia avoidance behaviour of snapper (Pagrus auratus) with only subtle changes in aerobic and anaerobic function

“…one measure of every 10min) according to standard formulae, detailed previously (Cook et al, 2011). SMR was thus resolved over 40h of normoxia using 240 measures of M O2 and the 15% quantile method (Chabot and Claireaux, 2008;Cook et al, 2011;Dupont-Prinet et al, 2010). RMR was defined as the mean M O2 throughout the duration of recording.…”

Rainbow trout in seasonal environments: phenotypic trade‐offs across a gradient in winter duration

“…2009; Dupont‐Prinet et al. 2010). But, high metabolic rate and food processing ability are known to reduce starvation endurance during periods of energy deficit (Afik and Karasov 1995; Cant et al.…”

“…1993; Post and Parkinson 2001; Hurst and Conover 2003; Dupont‐Prinet et al. 2010) and endotherms (White and West 1977; Carey et al. 1978), allocate energy to storage in order to fuel overwinter metabolic demands.…”

“…Body size is an important component of the energetic equation governing overwinter survival because, proportional to their mass, small individuals have higher metabolic rates and lower energy reserves relative to larger individuals (Post and Parkinson 2001; Hurst and Conover 2003; Dupont‐Prinet et al. 2010). …”

“…1996; Gotthard 2001; Post and Parkinson 2001; Dupont‐Prinet et al. 2010), and (3) the metabolic demands of rapid growth and food processing ability during the growing season and decreased tolerance of starvation in the winter. A simplified bioenergetics model (modified from Hanson et al.…”