Environmental enrichment influences spatial learning ability in captive-reared intertidal gobies (Bathygobius cocosensis)

Behavioural plasticity is an advantageous trait for animals living in dynamic environments, and can be induced through learning. While some behavioural traits are innate, others are framed by experience and learning during an individual's lifetime. Many studies have investigated cognitive abilities in fish species from contrasting environments, but the relative contribution of natural selection versus behavioural plasticity in cognitive variability remains equivocal. Furthermore, rearing conditions in laboratories are often mundane, failing to encourage natural behaviour in the species used in these studies. Here, we captured juvenile gobies (Bathygobius cocosensis) from intertidal rockpools, and raised them in captivity under varied environmental enrichment treatments that mimic variation observed in coastal habitats. When tested in a simple spatial learning task, individuals from complex rearing treatments (rock or oyster substrate) reached learning criteria faster than those reared in less complex (seagrass) and homogenous environments (sand substrate). Interestingly, gobies reared in complex environments demonstrated longer latencies to start the task than gobies in homogeneous treatments. Our results indicate that cognitive ability is strongly shaped by individual experience during ontogeny, and exposure to reduced environmental complexity in early life leads to reduced cognitive abilities in intertidal gobies.