Relationships Between Oceanic Primary Production, Human Habitation and Variation in the Life‐History Traits of Coral Reef Fishes Across the Northern Line Islands

Biophysical processes associated with large‐scale nearshore oceanographic upwelling can influence coral reef communities by increasing the delivery of nutrient subsidies and food resources to reefs. However, these processes occur alongside anthropogenic activities that may alter ecological patterns across coral reef ecosystems. We examined relationships among nearshore oceanic primary production, human habitation, and the abundance, biomass, body condition and life‐history traits of eight common coral reef fish species across six islands in the Northern Line Islands, central Pacific Ocean. Variation in oceanic primary production and habitation status was associated with differences in abundance, biomass, body condition and life‐history traits (i.e., growth rates, maximum size and longevity) of key coral reef fishes. These relationships varied among species and islands, with some taxa exhibiting more pronounced relationships with productivity and human habitation than others. Among uninhabited islands, several grazer‐detritivore species exhibited life‐history patterns that were consistent with variation in oceanic primary production, whereas these relationships between productivity and life‐history traits were less apparent among inhabited islands. In contrast, piscivore‐invertivore species generally exhibited stronger differences associated with human habitation status. These findings suggest that local human impacts may influence life‐history traits of reef fishes even when strong gradients in oceanic primary production are present. Although the mechanisms underlying these patterns were not evaluated directly, our results highlight the role of biophysical processes in shaping coral reef fish assemblages and suggest that human activities may alter ecological relationships linking environmental conditions and life‐history traits across tropical reef ecosystems.