Gut content and microbial diversity and composition of wild abalone populations and the associated environmental samples
The New Zealand black-footed abalone, Haliotis iris, is of substantial ecological, economic, and cultural value. Abalone from the Chatham Islands fishery contributes a significant proportion of the national catch but exhibits high variability in growth rates across populations. To investigate the potential of microbiome-linked growth variability, sub-adult and adult abalone from four populations were collected and analyzed via morphometric comparisons and 16S rRNA Illumina MiSeq sequencing. Adult abalone collected from Ascots Beach and Wharekauri (historically considered abalone fast-growing sites) were heavier and longer with larger tissue areas, compared to abalone from Owenga Harbour and Point Durham ( historically slow-growing sites), with no size difference observed in sub-adult animals. From seaweed species retreived from? the gut of adult abalone, animals from the fast-growing sites had larger quantities of red algae and lower quantities of green algae, while brown algae were the dominate species present in abalone from all four collection sites. Diversity metrics showed no difference in species richness while adult abalone from Point Durham had a higher abundance of microbes. The core bacteria within adult and sub-adult abalone from all study sites consisted of Psychrilyobacter, Mycoplasma, and Vibrio, which strongly relates to micrograms that digest seaweed as described in literature. Other microbiota links to environmental conditions that will benefit future studies to clarify the relationship. This study serves as a reference baseline for wild adult and sub-adult, H. iris gut microbiota from the Chatham Islands. Understanding how the gut microbiota differs among wild abalone populations with differentiated seaweed type and growth rate characterizations can provide insight into the roles of algal nutrients and gut-bacteria-mediated digestion in supporting abalone growth. Such information may inform sustainable and efficient management and harvesting practices of this endemic species, contributing to long-term fishery viability.