Metabolic fright responses of different-sized largemouth bass (Micropterus salmoides) to two avian predators show variations in nonlethal energetic costs

Steven J Cooke, Jeff Steinmetz, Jacob F Degner, Emily C Grant, David P Philipp
2003 Canadian Journal of Zoology  
Recently, researchers have identified that nonlethal costs of predation may arise not only from lost energy intake but also potentially from increased energetic expenditure. During periods of heightened stress following unsuccessful predation attempts, organisms may remain in an altered physiological state with elevated metabolism for some time. Few studies have quantified these nonlethal energetic costs of predation. We monitored the cardiac response (cardiac output (Q), heart rate (f H ), and
more » ... stroke volume (SV H )) of largemouth bass, Micropterus salmoides, ranging in size from 200 to 425 mm, to simulated avian predation attempts by great blue heron, Ardea herodias, and osprey, Pandion haliaetus. Fear bradycardia during a 30-s predation attempt varied depending upon the size of the fish and the type of predator. The magnitude of the bradycardia decreased with increasing size of the fish; however, the disturbances were more extreme in response to osprey than to blue heron models. Maximal cardiac disturbance following simulated predation attempts by osprey were consistent among size classes of bass. However, the magnitude of the disturbance following heron predation attempts reduced as the size of the fish increased. Size-specific trends were even more extreme for cardiac-recovery durations. Largemouth bass of all sizes exposed to osprey predation attempts required -40 min for Q and f H and -30 min for SV H to return to predisturbance levels. Although small bass exposed to heron predation attempts required recovery times similar to fish exposed to osprey predation attempts, as the size of largemouth bass exposed to the heron model increased above -300 mm, the recovery time decreased significantly. We conclude that the size-specific response of largemouth bass to different predators is reflective of their ability to assess the risk posed by different predators. In addition, the nonlethal costs of predation can be substantial and should be considered in future bioenergetics models. diminuait en fonction inverse de la taille du poisson. Les tendances spécifiques à la taille étaient encore plus extrêmes pour ce qui est de la durée de la récupération cardiaque. Chez les achigans à grande bouche de toutes les tailles soumis aux tentatives de prédation des balbuzards, il fallait -40 min pour que Q et ƒ H et -30 min pour que SV H retrouvent leurs valeurs initiales d'avant l'attaque. Bien que les petits achigans exposés aux attaques du héron aient requis le même temps pour récupérer que les poissons exposés au balbuzard, à mesure que la taille des poissons exposés au héron augmentait au-delà de -300 mm, le temps nécessaire à la récupération diminuait significativement. Nous concluons que, chez les achigans à grande bouche, la réaction spécifique à la taille à différents prédateurs reflète leur capacité d'évaluer les risques que posent les diverses espèces de prédateurs. De plus, les coûts non létaux de la prédation peuvent être élevés et devront désormais être pris en compte dans les modèles de bioénergétique. [Traduit par la Rédaction] Cooke et al.
doi:10.1139/z03-044 fatcat:zcsknonrszbttap7v4n7bt2ikm