Background Corals are known for their symbiotic relationships, yet there is limited evidence of chemoautotrophic associations. This is despite some corals occurring near cold seeps where chemosymbiotic fauna abound including mussels that host sulfur-oxidizing chemoautotrophs from the SUP05 cluster (family Ca. Thioglobaceae). We investigated whether corals near cold seeps associate with related bacteria and report here that these associations are widespread. Results We screened corals, water, and sediment for Thioglobaceae using 16S metabarcoding and found ASVs associated with corals at high relative abundance (10 – 91%). These ASVs were specific to coral hosts, absent in water samples, and rare or absent in sediment samples. Using metagenomics and transcriptomics, we assembled the genome of one phylotype associated with Paramuricea sp. B3 (ASV 4) which contained the genetic potential to oxidize sulfur and fix carbon, and confirmed that these pathways were transcriptionally active. Furthermore, its relative abundance was negatively correlated with the stable isotopic composition of its host coral’s tissue suggesting some contribution of chemoautotrophy to the coral holobiont. Conclusions We propose that some lineages of Thioglobaceae may facultatively supplement the diet of their host corals through chemoautotrophy at seeps or may provide essential amino acids or vitamins. This is the first documented association between chemoautotrophic symbionts and corals at seeps and suggests that the footprint of chemosynthetic environments is wider than currently understood.

Global warming is causing widespread coral mortality through bleaching. Here, simulations of coral eco-evolutionary dynamics forecast strong population declines in the 21st century. Coral reefs may co...

Climate change threatens coral reefs globally. Birkart and Alvarez-Filip document local extirpation of a keystone coral species in Mexico following unprecedented heat stress, suggesting similar outcomes for ∼70% of the Greater Caribbean’s shallow-water reefs. This highlights the need to upscale surveys using emerging technologies to locate, protect, and propagate surviving corals.

SUVA, FIJI, October 21, 2025 - A new study led by WCS, University of the South Pacific, and partners has found that coral reefs in Fiji showed remarkable resilience after being battered by Category 5 ...

The crucial reef-building corals were decimated by a marine heat wave in the Florida Keys. Can advances in restoration help them recover?

Florida’s primary reef-building corals have been declared ‘functionally extinct’ — prompting a shift in conservation strategies.

Florida’s primary reef-building corals have been declared ‘functionally extinct’ — prompting a shift in conservation strategies.

In 2023, a record-setting marine heat wave triggered the ninth mass coral bleaching event on Florida’s Coral Reef (FCR). We examined spatial patterns of heat exposure along the ~560-kilometer length o...

A record 2023 heat wave all but eradicated two species of coral that historically served as the backbone of Florida's reefs, researchers said in a new report.

Elkhorn and staghorn coral are now functionally extinct around the state, researchers say, meaning they no longer play any significant role in their ecosystem.

I am a second-year Environmental Science major at Santa Rosa Junior College and will be transferring to UC Santa Cruz this fall to complete my undergraduate degree. I spent my summer at the Bodega Mar...