Microhabitat patchiness structures benthic biodiversity in the Western Antarctic Peninsula

In the accelerating global biodiversity crisis, it is imperative to document biodiversity patterns along with their underlying drivers. To support this, ecological studies must identify the processes driving species distributions. Our objective was to study how benthic community variability is structured across spatial scales, and how fine-scale patchiness contributes to larger scale biodiversity in the Western Antarctic Peninsula. Using underwater imagery, we quantified benthic community composition at different scales using a nested sampling design. We used cluster analyses (NMDS, SIMPROF and SIMPER analysis) to detect patterns in benthic community variability. NMDS showed that seemingly different stations had many similar images. Images were clustered according to their community composition into 31 signifcant clusters, or microhabitat types, which were not divided by geographic location, substrate type or macroalgal cover, like initially presumed. Instead, the differences in faunal assemblage seem to be influenced by the dominant macroalgae species and biogenic habitat complexity. All in all, we found that these microhabitats emerge as ecologically meaningful units that offer a practical scale at which to detect patterns and early ecological shifts. Changes in the distribution or frequency of these microhabitats may occur before shifts in species composition become detectable at site or station level, which is crucial for ecosystem monitoring.