Sara E. Cannon, PhD

I am thrilled to share this new open-access publication, out today in Global Change Biology! This research is based on a chapter of my PhD dissertation. It was a massive effort that brought together 44 individual authors from 39 different institutions, to create a dataset of genus-level macroalgal percent cover across the Indian and Pacific Oceans that we used in the analysis.

Scientists and managers rely on indicator taxa like coral and macroalgal cover to evaluate the effects of human disturbance on coral reefs, but our new study suggests that this approach may be oversimplifying the complex relationships between specific macroalgae taxa and local human-driven disturbance.

The study used genus-level monitoring data from 1,205 sites in the Indian and Pacific Oceans to assess whether macroalgae percent cover correlates with local human disturbance while accounting for factors that could obscure or confound relationships.

We found that no genera of macroalgae were positively correlated with all human disturbance metrics. Instead, we found relationships between the division or genera of algae and specific human disturbances that were not detectable when pooling taxa into a single functional category, which is common to many analyses. The convention to use percent cover of macroalgae as an indication of local human disturbance may therefore be oversimplifying the issue and obscuring signatures of local anthropogenic threats to reefs.

The study highlights the need for a more nuanced and comprehensive approach to understanding the complex relationships between human disturbance and macroalgal cover on coral reefs. Our limited understanding of these relationships impedes our ability to diagnose and respond appropriately to these threats. The findings of this study will be important for scientists and managers working to protect and conserve coral reefs in the face of increasing human disturbance and climate change.