Results
We identified 41 studies that evaluated the effect of the understory on marine canopies, yielding 337 interaction estimates, spanning 46 canopy-forming species from four orders and 61 distinct turf seaweed species (Appendix S2 Figure S1). Studies were drawn from multiple biogeographic regions on five continents, as early as 1973, co-occurring with regions in which canopy-turf regime shifts have occurred (Filbee-Dexter & Scheibling 2014; Fig. 2). Overall, we found little evidence of publication bias in our dataset, supporting the results we describe below (Appendix S2).