Multiscale Spatial Variability and Stability in the Structure and Diversity of Bacterial Communities Associated with the Kelp Eisenia cokeri in Peru

Abstract

Ecological communities are structured by a range of processes that operate over a range of spatial scales. Whilst our understanding of such biodiversity patterns in macro-communities is well studied, our understanding at the microbial level is still lacking. Bacteria can be free living or associated with host eukaryotes, forming part of a wider "microbiome", which is fundamental for host performance and health. For habitat forming foundation-species, host-bacteria relationships likely play disproportionate roles in mediating processes for the wider ecosystem. Here, we describe host-bacteria communities across multiple spatial scales (i.e., from 10s of m to 100s of km) in the understudied kelp, Eisenia cokeri, in Peru. We found that E. cokeri supports a distinct bacterial community compared to the surrounding seawater, but the structure of these communities varied markedly at the regional (~480 km), site (1-10 km) and individual (10s of m) scale. The marked regional scale differences we observed may be driven by a range of processes, including temperature, upwelling intensity or regional connectivity patterns. However, despite this variability, we observed consistency in the form of a persistent core community at the genus level. Here, the genera Arenicella, Blastopirellula, Granulosicoccus and Litorimonas were found in >80% of samples and comprised ~53% of total sample abundance. These genera have been documented within bacterial communities associated with kelps and other seaweed species from around the world and may be important for host function and wider ecosystem health in general.

Bacteria on the foundational kelp in kelp forest ecosystems: Insights from culturing, whole genome sequencing and metabolic assays

“…Despite the growing knowledge of microbes associated with kelp (King et al, 2022 , 2023 ), relatively little is known about the contribution of these microbes to the health of their hosts. Metabolic analyses, using metagenomics or 16S amplicon sequencing, have grouped the metabolisms of multiple taxa into broad categories (Lin et al, 2018 ; Miranda et al, 2022 ; Selvarajan et al, 2019 ; Weigel et al, 2022 ).…”