Delayed recovery and host specialization may spell disaster for coral-fish mutualism

Abstract

Mutualisms are prevalent in many ecosystems, yet little is known about how symbioses are affected by multiple disturbances. Here we show delayed recovery for 13 coral-dwelling goby fishes (genus Gobiodon) compared with their host Acropora corals following 4 consecutive cyclones and heatwaves. While corals became twice as abundant 3 years post-disturbances, their symbiotic gobies were only half as abundant relative to pre-disturbances and half of the goby species disappeared. Although goby species preferred particular coral species, surviving goby species shifted hosts to newly abundant coral species when their preferred hosts became rare. As host specialization is key for goby fitness, shifting hosts may have negative fitness consequences for gobies and corals alike and affect their survival in response to environmental changes. Our study demonstrates that mutualist partners do not respond identically to multiple disturbances, and that goby host plasticity, while potentially detrimental, may be the only possibility for early recovery.