The physiological correlates of behavioural personality in Forsterygion lapillum and Pagrus auratus

Abstract

Animal personality refers to consistent individual differences (CIDs) in behaviour that are consistent or largely maintained over a period of time and/or across situations. CIDs in behavioural personality could potentially be linked with the large level of inter-individual variation in energy metabolism that physiologists commonly observe. This inter-individual variation in basal metabolic rate is commonly thought to encourage CID’s in behavioural traits, where higher metabolic rates are thought to support costly behavioural processes. For example, individuals with higher basal metabolic rates are likely to be more active, aggressive and bold in contexts related to food acquisition. Individual Forsterygion lapillum and Pagrus auratus were screened for their willingness to take risks to a series of tests: (1) exposure to a novel environment, (2) exposure to a novel object and (3) exposure to food. They were later screened for standard metabolic rate (SMR) to resolve whether risk-taking is indeed associated with maintenance metabolism. Contrary to current research, Forsterygion lapillum showed little consistency in their willingness to take risks when presented with the same stimuli in the presence and absence of food (P=0.463). In addition, their willingness to take risks was not significantly correlated with their standard metabolic rates (SMR= 0.120.09 mgO2 g-1 h-1) in any of the given situations. However, marked consistent differences in behaviour and physiology were evident in Pagrus auratus and results displayed significant correlations between behaviour and physiology. For example, individuals with high SMR (>145 mgO2. kg-1 h-1) were the first to explore a novel environment and object and were generally more active in a novel, potentially threatening environment. Bold and timid Pagrus auratus, later exposed to an environmentally related stressor, hypoxia, showed significant differences in the stress related release of cortisol but did not differ in maximum metabolic rate, metabolic scope or Pcrit during a decline in dissolved oxygen. This study is important because it demonstrates that CIDs in behaviour not only exist in snapper but they are tightly coupled with metabolism and stress physiology. The implications of these observations will be discussed with respect to the fisheries management of snapper in New Zealand.