Revisiting the evidentiary basis for ecological cascades with conservation impacts

Abstract

AbstractComplex ecological interactions are widely utilized to deliver conservation benefits but their efficacy is often debated. Using a coral reef trophic cascade as an example, we reveal that outcomes can be surprisingly difficult to detect. Even important impacts of marine reserves can go undetected (20% more coral with power < 0.5). This evidentiary challenge is compounded by misinterpretation of “nonsignificant” results as evidence of failed conservation practice. We illustrate a more appropriate analytical approach using a Bayesian Region of Practical Equivalence (ROPE) whereby many tests of conservation practice would be interpreted correctly as “undecided” rather than “negative.” Practitioners working with ecological cascades will increasingly be faced with “undecided” evidence of conservation benefits. Since one solution is to consider a wider diversity of evidence, we provide a hierarchy of evidentiary quality. In this way, even reductionist evidence of the component ecological interactions can be utilized, which is far easier to collect and evaluate.