Bed-scale rockweed harvest findings are not altered by study critiques, a response to Seeley et al.

Abstract

Seeley et al., 2024 (Comment: A reexamination of Johnston et al., 2023, bed-scale impact and recovery of a commercially important intertidal seaweed. J. Exp. Mar. Biol. Ecol. 574) describe a number of reasons that they believe our study's experimental design was flawed and our inferential conclusions were incorrect. We believe that these claims are the result of misunderstandings of the objectives behind our sampling design and statistical analyses. Throughout this response to Seeley et al., we reiterate key objectives of our study design: examining rockweed harvest at a whole-bed scale, realistically capturing the effects of current commercial rockweed harvest methods in Maine, and using coastwide site averages to estimate effect sizes of rockweed harvest. The first claim by Seeley et al. that our study design severely undersampled rockweed beds ignores established sampling methodologies in rockweed research. The suggestion that our sampling design resulted in impact sites that were de facto control sites is not supported by our analyses that showed greater declines in mean rockweed height and biomass at impact sites relative to control sites. In response to their second claim that rockweed companies had control of key elements of our study design and execution, we detail our specific approaches to lessen any possibility for such conflicts to bias our findings. In the final section of our response, we present power analyses in support of our Before-After Control-Impact study design and we highlight the statistically significant effects of treatment on rockweed biomass that contradict Seeley et al.'s claim that we drew conclusions about biomass recovery based solely on large p-values.