Habitat quality effects on the abundance of a coral‐dwelling fish across spatial scales

Microhabitat associated fishes are expected to be negatively affected by coral reef degradation, given that many species are coral dwellers. However, the factors underlying this negative impact and the spatial scale(s) at which it occurs are poorly understood. We explored how habitat quality metrics and host preferences influence fish abundance across multiple spatial scales, using the functionally important cleaner fish <i>Elacatinus evelynae</i> as a study species. We surveyed fish at 10 sites in Curaçao that varied in coral cover and health. At the microhabitat scale, we found that <i>E</i>. <i>evelynae</i> group size increases on large, healthy corals and on some coral host species, namely <i>Montastraea cavernosa</i>. We also found that, although <i>E</i>. <i>evelynae</i> can occupy at least 10 coral host species, it selectively inhabits just three corals: <i>M</i>. <i>cavernosa</i>, <i>Colpophyllia natans</i>, and <i>Diploria labrynthiformis</i>. Scaling up to explore goby abundance along 30-m transects, we did not find a clear relationship between live coral cover and goby abundance. However, goby abundance was substantially higher at one location with elevated coral cover and a high relative abundance of <i>E</i>. <i>evelynae</i> host species. Collectively, these results confirm that <i>E</i>. <i>evelynae</i> abundance is impacted by reef health. They also indicate that the species' long-term persistence may depend on both the maintenance of healthy coral hosts and the gobies' plasticity in host preferences on changing reefscapes. Cryptobenthic fishes such as <i>E</i>. <i>evelynae</i> play a vital role in the ecosystem and understanding drivers of their abundance is important as reefs face increased degradation.