Commentary: Tropical fish diversity enhances coral reef functioning across multiple scales

Lefcheck et al. (2019) sought to show the beneficial effects of tropical fish biodiversity on coral reef ecosystem functioning at multiple scales. To do so, they collected data from video and transect surveys at 10 sites to determine whether alpha and beta species diversity of fish led to an increase in ecosystem functioning in the form of higher grazing rates at multiple scales and whether grazing rates enhanced ecosystem structure by reducing turf abundance and promoting coral abundance. Below, we describe a number of major conceptual and statistical flaws in their study that undermine their results and conclusions.