The skin microbiome as a new potential biomarker in the domestication and welfare of Octopus vulgaris

Abstract

Over the past decade, there has been a growing interest in common octopus aquaculture, prompted by the increasing market demand, the decline in overall fisheries and the search for a more sustainable food resource. Nevertheless, this interest has raised concerns about the potential impact of large-scale production and intensified farming practices in the future. Given the growing interest in octopus aquaculture and society's increasing concern for animal welfare, this study investigates the mucosal skin microbiota of wild and captive-bred common octopuses. The primary aim is to determine if breeding in captivity affects these communities and consequently animal welfare, using 16S ribosomal RNA metabarcoding. The core microbiota of common octopus mucosal skin is composed of the phyla Bacteroidota, Proteobacteria, Campylobacterota and Verrucomicrobiota, according to our findings. Although variations in abundance were observed, wild and aquaculture octopuses had comparable microbiota composition and diversity. Gammaproteobacteria were found to be enriched in wild mucosal skin samples, and some of the species were described as potentially pathogenic. However, these species were absent or in lower abundance in aquaculture mucosal skin samples. Additionally, analysis of KEGGs predictions showed that wild mucosal skin samples had a higher overall enrichment in functional pathways, primarily associated with xenobiotic remediation pathways, compared to the aquaculture mucosal skin samples. This is the first study to characterize the mucosal skin microbiome of the common octopus and compare the microbiome of wild and aquaculture individuals of this species. The results indicate that current aquaculture practices align with animal welfare through the use of controlled hatchery environments and high-quality water conditions. This study offers valuable insights into the microbiome of the common octopus, which can serve as a biomarker for evaluating animal welfare. It also explores the implications of these findings for the development of sustainable and responsible aquaculture practices.