Researchers have uncovered a rare deep-sea site where hot hydrothermal vents and cool methane seeps occur side by side, creating a vibrant ecosystem. Located 1,300 meters deep on Conical Seamount near Lihir Island, this previously unknown field teems with mussels, tube worms, and other marine life. The discovery highlights both geological wonders and threats from nearby mining.
Off the coast of Papua New Guinea, a team of scientists has identified an exceptional hydrothermal field on the slope of Conical Seamount. At about 1,300 meters depth, hot fluids from volcanic activity rise alongside large quantities of methane and hydrocarbons from sediments—a combination never documented before. This hybrid system was revealed during the 2023 SONNE expedition SO299 DYNAMET, which surveyed underwater volcanoes in the Tabar-Lihir-Tanga-Feni island chain.
Dr. Philipp Brandl, a marine geologist at GEOMAR Helmholtz Centre for Ocean Research Kiel and chief scientist on the expedition, described the find: "We essentially have a hot vent bubbling right next to a cool gas seep—a combination that has never been described before." The site's unusual features emerged only when the team deployed the ROV Kiel 6000, surprising veterans of the area. "No one really expected to find a hydrothermal field here, let alone one that is so exceptional," Brandl added.
The close proximity of vents and seeps stems from Conical Seamount's structure: organic-rich sediments heated by magma produce gases that escape through the same pathways as chemically rich fluids. This fosters a dense community of organisms, including Bathymodiolus mussels, tube worms, shrimp, amphipods, and purple sea cucumbers covering the rocks. Named 'Karambusel'—meaning 'mussel' in Tok Pisin—due to the mussel dominance, the site may harbor undescribed species.
Geologically, the area shows traces of gold, silver, arsenic, antimony, and mercury in the rocks from past high-temperature activity. However, threats loom from human activities, including the nearby Ladolam gold mine on Lihir Island, which discharges waste into the ocean, and existing exploration licenses for seafloor minerals and hydrocarbons. Brandl urges protection: "We have discovered an unexpected treasure trove of biodiversity in the Karambusel field that needs to be protected before economic interests destroy it."
The findings appear in Scientific Reports.