Climate change has a negative impact on fish social behavior and abundance

Climate change poses a major threat to coral reef ecosystems worldwide. Here, we present the immediate negative effects of recent cyclones and the 2016 El Niño on the abundance of cleaner wrasse <i>Labroides dimidiatus</i> (hereafter ‘cleaner’), a key species for fish biodiversity on coral reefs. We report that 80% of cleaner densities was lost. Consequently, several repercussions on cleaners social behavior were observed. We outline significant decline in the ability of cleaner to manage their own reputation and strategically prioritize certain category of client reef fish, previously documented as key components of cleaner high cognitive performance in the cleaning mutualism. Thus, contemporary climate change may cause diverse and unexpected effects on species abundance and social interactions, possibly due to the loss of more complex cognition.