This study investigated the impact of 50 years of warming on benthic microbial communities in a Baltic Sea bay, using a nearby bay as a control. The heated bay showed reduced oxygen, decreased anaerobic electron acceptors, and higher sulfate reduction rates. Analyses revealed anaerobic reactions closer to the sediment-water interface, higher microbial diversity, increased sulfate reduction and methanogenesis transcripts, and higher production of toxic sulfide and methane. While metatranscriptomics indicated increased energy production, numerous stress transcripts suggested weakened community resilience, indicating a potential negative feedback loop where increased temperatures amplify negative effects on coastal biogeochemical cycling.

Laura Seidel, Marcelo Ketzer, Elias Broman, Sina Shahabi-Ghahfarokhi, Mahboubeh Rahmati-Abkenar, Stephanie Turner, Magnus Ståhle, Kristofer Bergström, Lokeshwaran Manoharan, Ashfaq Ali, Anders Forsman, Samuel Hylander, Mark Dopson