Appendix C. Coral colony size frequency distribution.

Coral colony size frequency distribution

Appendix E. Total prey colonization.

Total prey colonization

Appendix A. Trophic level assignments from surveys.

Trophic level assignments from surveys

Human, Oceanographic and Habitat Drivers of Central and Western Pacific Coral Reef Fish Assemblages

<div><p>Coral reefs around US- and US-affiliated Pacific islands and atolls span wide oceanographic gradients and levels of human impact. Here we examine the relative influence of these factors on coral reef fish biomass, using data from a consistent large-scale ecosystem monitoring program conducted by scientific divers over the course of >2,000 hours of underwater observation at 1,934 sites, across ~40 islands and atolls. Consistent with previous smaller-scale studies, our results show sharp declines in reef fish biomass at relatively low human population density, followed by more gradual declines as human population density increased further. Adjusting for other factors, the highest levels of oceanic productivity among our study locations were associated with more than double the biomass of reef fishes (including ~4 times the biomass of planktivores and piscivores) compared to islands with lowest oceanic productivity. Our results emphasize that coral reef areas do not all have equal ability to sustain large reef fish stocks, and that what is natural varies significantly amongst locations. Comparisons of biomass estimates derived from visual surveys with predicted biomass in the absence of humans indicated that total reef fish biomass was depleted by 61% to 69% at populated islands in the Mariana Archipelago; by 20% to 78% in the Main Hawaiian islands; and by 21% to 56% in American Samoa.</p></div

Appendix B. Reef configuration.

Reef configuration

Appendix D. Predation and rarefaction.

Predation and rarefaction

Smoothers of predictor variables retained in highest ranked models of ‘all fishes’ and of consumer groups.

<p>Shaded areas show 95% confidence.</p

Reef Fish Reference Points generated from model predictions with HSUM and HDIST set to 0.

<p>The bars are fish biomass (+95% CI per island). The gray bars are model predictions in absence of humans (low to high CI). Remote and uninhabited islands (left hand panel) are sorted from high to low CHL. Human-populated islands (right hand panel) are sorted from low to high human population density per unit reef area. ‘Remote-uninhabited’ reef areas include places with small resident populations of managers or researchers, but where harvest of reef fishes is prohibited (Midway, Palmyra).</p

Visualization of smoothers for (a) local humans per area of forereef (HUM) and (b) Chlorophyll-a (CHL).

<p>Smoothers were generated using the <i>predict</i> function, with data values held at variable means for variables other than the predictor, which was set to values equally spaced between the min and max across all reef areas. Scales of response are shown as proportion of biomass at (i) no humans; and (ii) min CHL.</p

Island-scale predictor variables.

<p>Values represent island-means: CHL, WV and SSTL were obtained from satellite-derived sources [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0120516#pone.0120516.ref007" target="_blank">7</a>] and represent long-term (9–25 yr.) averages of oceanic waters surrounding. HC and CX are visually-estimated by divers during fish surveys. Human population data per island comes from the 2010 US census (<a href="http://www.census.gov/2010census/" target="_blank">http://www.census.gov/2010census/</a>). Area of <30m hard-bottom habitat per island comes from CRED GIS maps used for survey design, and collated from a range of internal and external sources. Island-scale values calculated as weighted averages of all sites within an island. Island-scale weighting of sites described in the Methods section.</p><p>Island-scale predictor variables.</p