We report the discovery and detailed analysis of an extraordinary colonial spider assemblage in Sulfur Cave, a chemoautotrophic sulfidic ecosystem located on the Albania-Greece border. The colony, comprising an estimated 69,000 individuals of Tegenaria domestica (Agelenidae) and more than 42,000 of Prinerigone vagans (Linyphiidae), spans a surface area of over 100 m²—representing the first documented case of colonial web formation in these species.

We report the discovery and detailed analysis of an extraordinary colonial spider assemblage in Sulfur Cave, a chemoautotrophic sulfidic ecosystem located on the Albania-Greece border. The colony, com...

We report the discovery and detailed analysis of an extraordinary colonial spider assemblage in Sulfur Cave, a chemoautotrophic sulfidic ecosystem located on the Albania-Greece border. The colony, com...

Deep underground in a dark, sulfuric cave on the border between Albania and Greece, scientists have made an incredible discovery – a giant communal spider web spanning more than 100 square meters (1,0...

Aquatic environments absorb ~2.5 gigatonnes of atmospheric carbon each year, more than the carbon stored in the atmosphere, soils, and all biomass combined. Primary producers transform this dissolved inorganic carbon into biomass that can subsequently flow into other trophic levels, or be released back into the environment through viral lysis. While there is substantial knowledge about the diversity and activity of viruses infecting photoautotrophic primary producers, little is known about viruses infecting chemoautotrophs, representing a gap in our understanding of key microbial processes driving global carbon cycles. Here, we combine metagenomics with 12/13C stable isotopic probing mesocosm experiments in a marine-derived meromictic pond to quantify lineage-specific carbon cycling activity to identify key microbial populations driving carbon cycling. We then tracked the flow of carbon from active chemoautotrophs to their viruses and found evidence supporting virus-mediated recycling of chemoautotrophic biomass through the production of viral particles. In particular, active populations of hydrogen/sulfur-oxidizing chemoautotrophs (Thiomicrorhabdus, Hydrogenovibrio, Sulfurimonas, Sulfurovum) were targeted by viruses. Considering the widespread distribution of chemoautotrophs on Earth, we postulate that this previously overlooked component of the microbial carbon cycle is a globally relevant process that has implications for our planet's carbon cycle. This work provides the foundation for revealing the role of viral lysis in chemoautotrophic primary production and builds toward biogeochemical models that incorporate viral recycling of chemoautotrophic biomass. ### Competing Interest Statement The authors have declared no competing interest. University of North Carolina at Charlotte, https://ror.org/04dawnj30

Aquatic environments absorb ~2.5 gigatonnes of atmospheric carbon each year, more than the carbon stored in the atmosphere, soils, and all biomass combined. Primary producers transform this dissolved inorganic carbon into biomass that can subsequently flow into other trophic levels, or be released back into the environment through viral lysis. While there is substantial knowledge about the diversity and activity of viruses infecting photoautotrophic primary producers, little is known about viruses infecting chemoautotrophs, representing a gap in our understanding of key microbial processes driving global carbon cycles. Here, we combine metagenomics with 12/13C stable isotopic probing mesocosm experiments in a marine-derived meromictic pond to quantify lineage-specific carbon cycling activity to identify key microbial populations driving carbon cycling. We then tracked the flow of carbon from active chemoautotrophs to their viruses and found evidence supporting virus-mediated recycling of chemoautotrophic biomass through the production of viral particles. In particular, active populations of hydrogen/sulfur-oxidizing chemoautotrophs (Thiomicrorhabdus, Hydrogenovibrio, Sulfurimonas, Sulfurovum) were targeted by viruses. Considering the widespread distribution of chemoautotrophs on Earth, we postulate that this previously overlooked component of the microbial carbon cycle is a globally relevant process that has implications for our planet's carbon cycle. This work provides the foundation for revealing the role of viral lysis in chemoautotrophic primary production and builds toward biogeochemical models that incorporate viral recycling of chemoautotrophic biomass. ### Competing Interest Statement The authors have declared no competing interest. University of North Carolina at Charlotte, https://ror.org/04dawnj30