Drajad Seto guided the Triton 3300/3 manned submersible Neptune down to nearly 950 meters below the surface, descending toward a seamount summit in Indonesia's remote tropical waters where few humans have ever ventured. From January 5 to 24, the University of Rhode Island postdoctoral researcher was one of the key scientific leads aboard the OceanX vessel, part of an unprecedented three-week expedition to document life on ecosystems that remain almost entirely unknown to science.
These underwater mountains—seamounts—rising from the ocean floor are often thought of as biodiversity hotspots, their peaks and slopes altering ocean circulation in ways that concentrate food and fuel rich deep-sea communities. Yet in Indonesia, home to some of the world's most extensive seamount chains, researchers have barely begun to map what actually lives there. "Seamounts are often described as biodiversity hotspots because their topography can alter ocean circulation and enhance productivity," Seto and his collaborators noted in their research framework. The expedition, organized through a competitive proposal process by Indonesia's National Research and Innovation Agency (BRIN), aimed to fill that gap with the first systematic biodiversity data from the region.
Seto worked alongside Indonesian scientists including Noer Kasanah from University Gadjah Mada, while his URI colleagues—Associate Professor Roxanne Beinart, professor Bethany Jenkins, and other members of the Graduate School of Oceanography—coordinated analysis from shore. Their strategy was two-pronged: deploy a remotely operated vehicle (ROV) to collect biological samples across multiple depths, then use both traditional DNA barcoding and environmental DNA (eDNA) metabarcoding to identify what they'd found. The eDNA approach detects genetic traces animals leave in the water, revealing species presence without needing to see or capture them directly—a crucial tool for understanding deep-sea life, where many creatures remain completely undocumented.
What makes this work especially valuable is not just what it discovers, but what it builds. By collecting organisms with the ROV and generating DNA barcodes for them in the lab, the team expanded the genetic reference databases that future researchers will depend on. "The research team aims to help establish baseline biodiversity observations that future studies can build on," reflecting how foundational this work is to understanding how animal communities shift from a seamount's summit to its deeper, darker slopes—and why some seamounts teem with life while others appear surprisingly sparse.
Beyond the deep ocean, the expedition revealed something equally intriguing in the shallows. Using a compact plankton imaging system called a PlanktoScope, BRIN scientists Mariana Intan and Ridho Sianturi worked with Seto to analyze surface waters above the seamounts. They found phytoplankton species associated with harmful algal blooms—the toxic events that kill fish, contaminate shellfish, and close fisheries. The discovery opens a tantalizing question: could offshore seamount regions serve as hidden reservoirs that seed blooms before they reach coastal waters? The team plans to investigate that hypothesis in future work.
What emerges from this expedition is not just a catalog of creatures, but the beginning of a conversation between international scientists and Indonesian institutions about stewarding some of the planet's least-known ecosystems. The collaboration itself signals a shift toward knowledge that belongs to the regions being studied.