Elevated seawater temperature disrupts the microbiome of an ecologically important bioeroding sponge

Area of Science:

• Marine Biology
• Microbial Ecology
• Symbiosis

Background:

• Bioeroding sponges contribute to reef erosion, a process exacerbated by climate change.
• Elevated ocean temperatures can negatively affect sponge health by disrupting microbial symbionts.

Purpose of the Study:

• To describe the microbial community of the bioeroding sponge Cliona orientalis.
• To assess the response of the C. orientalis microbiome to increasing seawater temperatures.

Main Methods:

• 16S rRNA gene sequencing was used to identify microbial taxa.
• Microbial community composition was analyzed across a temperature gradient (23°C to 32°C).

Main Results:

• The C. orientalis microbiome was dominated by Alphaproteobacteria, with Rhodothalassium sp. being a significant component.
• The core microbiome included nitrogen fixers and ammonia oxidizers, suggesting a role in nitrogen metabolism.
• Microbial community structure shifted at 29°C, prior to sponge bleaching at 32°C.
• Bleached sponges showed limited recovery of their microbiome and symbionts.

Conclusions:

• The C. orientalis microbiome is sensitive to thermal stress, with shifts occurring before visible signs of bleaching.
• Changes in the sponge's microbial community may precede and contribute to host destabilization under thermal stress.
• C. orientalis exhibits limited recovery potential from extreme thermal events.