Global warming is causing the increase in intensity and frequency of heatwaves, which are often associated with mass mortality events of marine organisms from shallow and mesophotic rocky habitats, including gorgonians and other sessile organisms. We investigated the microbiome responses of the gorgonians Paramuricea clavata, Eunicella cavolini, and the red coral Corallium rubrum to the episodic temperature anomalies detected in the North Western Mediterranean, during August 2011. Although the investigated corals showed no signs of visible necrosis, the abundance of associated Bacteria and Archaea increased with increasing seawater temperature, suggesting their temperature-dependent proliferation. Coral microbiomes were highly sensitive to thermal anomaly amplitude and exhibited increased bacterial diversity to greater thermal shifts. This effect was explained by the decline of dominant bacterial members and the increase of new, rare and opportunistic taxa, including pathogens, revealing a direct effect of heatwave-induced alteration of the microbiomes and not a secondary consequence of coral necrosis.

Depth range
15- 70 m

Mesophotic “mentions”
5 x (total of 8571 words)

Classification
* Presents original data
* Focused on 'mesophotic' depth range
* Focused on 'temperate mesophotic ecosystem'

Fields
Biodiversity
Climate Change
Community structure
Ecology
Molecular ecology

Focusgroups
Bacteria and Archaea
Octocorallia (Soft Corals)

Locations
Italy - Ligurian-Tyrrhenian

Platforms
SCUBA (open-circuit or unspecified)