Award: OCE-1736932

This award supported significant advances in our understanding of the foundation species at deep-sea hydrothermal vents. Deep-sea hydrothermal vents are underwater hot springs where superheated, mineral-rich fluids escape from the seafloor in what are essentially geysers. Despite the extreme conditionshigh temperatures, high pressure, and the absence of sunlightthese vents support unique ecosystems teeming with life. Instead of relying on photosynthesis like surface ecosystems, vent communities are powered by chemosynthesis, a process in which specialized bacteria convert chemicals from the vent fluids into energy. These bacteria form the base of the food web, supporting diverse animal species such as giant tube worms, mussels, snails, and shrimp. Many of these animals have evolved close symbiotic relationships with the bacteria, allowing them to thrive in these harsh environments. Our research highlights the important role that chemosynthetic bacteria play in the ecology and evolution of their animal hosts. Our experiments reveal how hydrothermal vent mollusks adapt to their unique environments and suggest that variations in their obligate bacterial partners may influence where these animals live. Studying hydrothermal vents provides insights into evolutionary adaptation, deep-sea biodiversity, and even the potential for life on other planets. By analyzing the genetics of three types of hydrothermal vent mollusks that are foundation species in their ecosystems Alviniconcha, Ifremeria, and Bathymodioluswe found that environmental conditions have a stronger influence on the types of symbiotic bacteria they host than the animals' own genetics. This supports the idea that vent animals associate with locally adapted bacterial strains to survive in these extreme habitats. Our findings also provide strong evidence that these bacteria are passed between individuals through the environment (horizontal transmission), rather than being inherited directly. Additionally, our research suggests that these symbiotic relationships may drive the evolution of new species by enabling animals to adapt to different ecological niches. While our study focuses on hydrothermal vents, it contributes to the broader understanding of how bacterial symbiosis influences evolution and ecology across different ecosystems. This award also supported opportunistic studies in the aftermath of the Hunga volcano eruption, since our oceanographic expedition arrived at study sites in Tonga only a few months after the eruption of this submarine volcano in 2022. We examined how the deposition of volcanic ash affected hydrothermal vent communities and found that species relying on chemosynthetic bacteria were particularly impacted, offering new insights into the vulnerability and resilience of vent ecosystems in response to both natural disasters and human disturbances. We also have contributed new understanding of how volcanic ash and debris are transported across the seafloor. Our data support previous findings that submarine density currents played a major role in redistributing volcanic and sediment material after the Hunga eruption. This award also helped make information about deep-sea chemosynthetic habitats, such as hydrothermal vents, more accessible to K-12 educators. It supported the creation of an educational guide that includes a glossary of key terms and a collection of lesson plans and other resources to help teachers introduce this fascinating topic to students. Last Modified: 02/03/2025 Submitted by: RoxanneBeinart