Habitat structure affect abundances of labrid fishes across temperate reefs in south-western Australia

Abstract

We tested the effect of reef complexity (number of small vs. large topographic elements,<1 m and >1 m, respectively), and composition of macroalgae (cover of the kelp Ecklonia radiata, fucalean and red algae) on the abundance patterns of labrid fishes across ~800 km of coastline in south-western Australia. Fishes and habitat attributes were visually counted at 12 reefs visited at four times over 1 year. Five labrids (Austrolabrus maculatus, Coris auricularis, Notolabrus parilus, Ophthalmolepis lineolata and Pseudolabrus biseralis) were frequently observed (>20% of counts), while three species (Bodianus axillaris, Choerodon rubescens and Thalassoma lutescens) were rarely censused (< 6%). Patterns of abundance were generally affected by two descriptors of the habitat structure: the number of small topographic elements (100 m−2), and the percentage of red algal cover. Most species showed a tendency for an increase in their abundances with an increase in the number of small topographic elements and cover of red algae. The patterns likely reflect an underlying correlation between habitat structure and prey accessibility and lowered predation risk.