Fish memory: cognition in reef fish
reef fish, learning, memory, heat stress.
Reef environments are highly complex, providing different types of environmental signals that need to go through processing steps to facilitate acquiring information and making decisions. Despite the existing myth around fishes' short memory and limited behavioral repertoire, for a long time considered only instinctive, the development of functions related to learning and memory is widespread among teleosts. These skills are crucial for survival in natural habitats. Many fish species can perform tasks from the simplest to the most complex. However, our knowledge about the variations involving task characteristics or the effects of environmental variables on cognitive processes is still scarce. The general objective of this thesis was to investigate factors related to the nature/complexity of the task in behavioral responses related to learning and memory in damselfish, using three species: Stegastes fuscus, Acanthochromis polyacanthus, and Amphiprion percula. We evaluated information retention time in appetitive and aversive conditioning tasks (chapter 1), We investigated the influence of familiarity on the mnemonic response maintenance over time (chapter 2), and We assessed spatial learning and memory in response to environmental warming (chapter 3). Our results showed that the nature of the stimulus does not seem to interfere with information retention for up to 15 days in S. fuscus, which sustain the mnemonic response 5, 10 and 15 days after aversive and appetitive conditioning. We observed that S. fuscus showed individual recognition and ability to remember conspecifics through the agonistic response, which was affected by the interval time for re-pairing with conspecifics (5, 10, and 15 days). In addition, we observed that A. polyacanthus learns and remembers a spatial navigation task for 5 days while A. percula does not learn the task. In this same task, the increase of 2°C damages memory while the increase of 4°C impairs the learning of A. polyacanthus. Given the vulnerability of reef environments, the understanding of aspects related to the learning and memory of individuals can provide science with valuable results for future management and conservation plans, in addition to contributing to the knowledge of the biology of damsels, which show an elaborate cognitive capacity.