Associations between health status, locality, and microbiota of the Menai Strait sponge Haliclona oculata.

Abstract

Sponges perform vital ecological roles within their benthic ecosystem. In recent decades, die-offs and declines in certain species have been linked to environmental pressures and/or pathogens, either via directly affecting the sponge itself or the microbiomes of the sponge holobiont. The microbiome of sponges often contains members unique to Porifera, and characterising their community compositions can reveal a great deal about their function. Sponges separate into two groups based on whether they have a low microbial abundance (LMA), or high (HMA). Haliclona oculata is an LMA sponge living in the Menai Strait, North Wales with recent reported declines in health. To investigate this, samples were taken from healthy and necrotic tissue, a comparison species A. fucorum, living sympatrically with H. oculata, and seawater samples, in multiple locations. Multi-marker DNA metabarcoding was utilised to profile and compare the bacterial (16S), algal (23S) and fungal (ITS) communities. In H. oculata, health status was more strongly associated with bacteria alpha and beta diversity than site. In contrast, site had a significant influence on algal microbiome community differences. Differential abundance of specific taxa and/or taxonomic groups between healthy and necrotic sponges may provide health indicators or suggest that sponges might be experiencing adverse conditions. Overall, this study provides a comprehensive overview of the microbiome differences between healthy and diseased H. oculata and a novel resource for investigating the ecology and health of temperate sponges.

Date of Award	30 May 2025
Original language	English
Awarding Institution	Bangor University
Sponsors	Natural Resources Wales
Supervisor	Kata Farkas (Supervisor) & Amy Ellison (Supervisor)