Local human impacts decouple natural biophysical relationships on Pacific coral reefs

Submitted by editor on 4 March 2015.

Remote coral reefs of the Pacific Ocean. Remote, uninhabited reefs such as these give us a glimpse into the natural structuring forces of ecological communities in a world without humans and highlight the important fact that not all coral reefs look the same. Natural variation in oceanography and climate lead to naturally-coupled changes in coral reef benthic communities, demonstrating that management targets for coral reef ecosystems must be context specific and consider the upper limit set by the surrounding natural environment. All photos: Brian J. Zgliczynski.

by Gareth John Williams

Can humans alter the fundamental rules of nature?

Looking at coral reef ecosystems across the Pacific the answer is yes. In an era where all ecosystems on our planet echo a footprint of human activity, it is challenging to separate the independent effects of natural variability in ecosystem structure from those caused by human-induced change. However, scattered across remote parts of the Pacific Ocean are uninhabited coral reef atolls and islands that offer a glimpse into a world without local human impacts. Many of these islands have lacked resident human populations throughout their entire geological history and are far from any substantial human population centers. Comparing these remote islands to islands harboring dense human populations, we found local human impacts alter biological communities in such a way that they are no longer naturally coupled with (or reflective of) the background environmental regime in which they are found. We term this phenomenon biophysical decoupling.