MEPS 586:141-154 (2018)  -  DOI: https://doi.org/10.3354/meps12378

ABSTRACT: We conducted an underwater survey to collect quantitative data on fish assemblages and various environmental factors on extensive reef slopes of Okinawa Island, southern Japan, and examined the relative influence of environmental factors on 6 trophic groups. Abundance and richness of most of the trophic groups were primarily affected by 1 of 2 factors, either percentage areal cover of bedrock or current velocity. For omnivores and mobile invertivores, abundance was relatively consistent across habitat types. Based on counts of fish species across 4 distinct habitat types, omnivores included more environmental generalist species occurring in multiple habitat types. In contrast, the consistent occurrence of mobile invertivores across habitat types was probably attributable to interspecific compensation, since species of this trophic function exhibited greater environmental specialization than omnivores did. Both species richness and abundance of herbivores and planktivores were more dependent on habitat type, and species included in these 2 trophic groups exhibited more consistent responses to environmental variation. Our results highlight the similarities and differences in responses to environmental variation among trophic groups, and the potential for environmental conditions to explain community structure and diversity in coral reef fishes. The realized niche width of species within each trophic group with respect to their habitat preference should be taken into consideration when developing effective conservation management strategies for coral reef fish communities.

KEY WORDS: Biodiversity · Physical and chemical environments · Environmental specialist · Environmental generalist · Ecological function · Species abundance · Species richness · Community assembly · Fringing reefs