Anela K. Akiona

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.

Length-weight parameters assist in the estimation of a fish’s biomass based upon assessment of length, providing value to many scientific and management applications. Some fish species have many sets of parameters published, while those less commonly studied may have no available information, making it challenging to decide which values to use. To address this, we present a database of quality-controlled length-weight parameters for 1,308 Pacific coral reef fish species from 87 families. The species included are commonly observed in visual censuses of shallow (10 m depth) forereef habitats of the central Pacific. These data were collated from the literature, and were selected based on study sample size, representation of the species’ total length range, and data confidence. The most speciose families, wrasses (Labridae) and damselfishes (Pomacentridae), were most common in our database, though a large proportion of these species remain data-poor. In total, this database serves as a valuable tool for the academic community as well as for partners and managers desiring to learn more about coral reef fish assemblages.

An increase in the intensity and frequency of extreme environmental conditions due to anthropogenic climate change impacts coral reefs through myriad stressors, from elevated sea-surface temperatures to increased storm activity. A reef’s response to these disturbances can be influenced by factors including taxonomic composition, life history strategies, or spatial patterning of the reef community members. We explored the disturbance-specific responses of coral reefs by following changes in benthic cover of major functional groups, community assemblage, and the response of common coral taxa at six islands across the central Pacific over the course of two years. We observed a decrease in average coral cover at four of the six islands, with differing underlying shifts in assemblage structure. Reefs with the highest pre-disturbance benthic coverage of Montipora spp. displayed significant increases in average hard coral cover compared to those where Acropora spp. was in the highest abundance; Acropora-dominated reefs showed significant declines in coral cover especially when exposed to the physical stress associated with a cyclone. Change in total coral cover was variable between islands within the same region, even among adjacent islands facing similar disturbance. These results highlight the importance of assemblage composition in influencing how benthic communities respond to major disturbance events such as thermal stress or cyclones. Improving our understanding of the drivers of differential community responses to disturbance will be important in predicting future changes in reef structure under changing ocean conditions.

Length-weight relationships (LWR) are valuable for fisheries stock assessments yet are often sparsely available for coral reef fishes. This study describes the LWR for 15 species of coral reef fish spanning seven families from the Northern Line Islands, a geographically remote and historically understudied area of the central Pacific. Specimens were collected across multiple field campaigns from 2006 to 2011, and the LWR were calculated using the linear regression of the log-transformed total length (TL, 0.1 cm precision) and weight (W, 0.01 g precision) data. Many of these species come from popular food fish families and contribute to large proportions of total reef fish biomass. We found that all but one of the Bayesian point estimates fell outside of the 95% confidence interval for our empirically derived LWR, which underscores the importance of studying under-sampled geographies.