Linking environmental variability and fish performance: integration through the concept of scope for activity

Abstract

Investigating the biological mechanisms linking environmental variability to fish production systems requires the disentangling of the interactions between habitat, environmental adaptation and fitness. Since the number of environmental variables and regulatory processes is large, straightening out the environmental influences on fish performance is intractable unless the mechanistic analysis of the 'fish-milieu' system is preceded by an understanding of the properties of that system. While revisiting the key points in our currently poorly integrated understanding of fish ecophysiology, we have highlighted the explanatory potential contained within Fry's (Fry 1947 Univ. Toronto Stud. Biol. Ser. 55, 1-62) concept of metabolic scope and categorization of environmental factors. These two notions constitute a pair of powerful tools for conducting an external (at the emerging property level) analysis of the environmental influences on fish, as well as an internal (mechanistic) examination of the behavioural, morphological and physiological processes involved. Using examples from our own and others work, we have tried to demonstrate that Fry's framework represents a valuable conceptual basis leading to a broad range of testable ecophysiological hypotheses.

Environmental constraints upon locomotion and predator–prey interactions in aquatic organisms: an introduction

“…Work by Wilson et al (2007) shows how conflict between the sexes in mating behaviour with thermal acclimation offers a range of future questions addressing the ecological implications of phenotypic plasticity and their consequences for sexual interactions in nature. With some examples, Claireaux & Lefrançois (2007) have illustrated how unravelling the environmental influences on phenotype performance and adaptive flexibility opens new fields of research, particularly in linking ecophysiology and evolutionary biology. Since environmental factors can affect a whole population, they are believed to be more effective initiators of selectable evolutionary novelties than mutations which initially only affect one individual (West-Eberhard 2005).…”

“…Full integration of laboratory and fieldwork is necessary to allow us to place environmental constraints within specific behavioural and ecological contexts, as well as to generate predictive environmental scenarios (Abrahams et al 2007;Claireaux & Lefrançois 2007). This would enhance our ability to predict community changes related to habitat degradation and the current trends of environmental change.…”

“…The behaviour of aquatic organisms is also constrained by environmental conditions (figure 1). This modulatory effect is either direct, such as the effect of turbidity on the prey-searching behaviour of fish (Meager & Batty 2007), or indirect, through the effect of temperature on the scope for aerobic activity in fishes, which determines the limits of their behavioural repertoire (Claireaux & Lefrançois 2007).…”

“…Despite significant effort, progress has been slow in placing our understanding of fish physiology within an ecological context. Claireaux & Lefrançois (2007) argue that Fry's 60-year-old monograph (Fry 1947) provides a valuable conceptual basis for linking physiology, ecology and evolutionary biology. Ecotoxicology is certainly one of the fields of environmental sciences that has been particularly successful at considering complex physiological traits of performance and their environmental determinants.…”

“…It has been argued that environmental conditions in aquatic systems are generally more stable than in their terrestrial counterparts but, whereas this may be the case for deep or pelagic habitats, it is certainly not the case for most coastal zones or freshwater systems. In such habitats, important environmental parameters can fluctuate to significant extents at a multiplicity of temporal and spatial scales (Abrahams et al 2007;Claireaux & Lefrançois 2007).…”