Predatory Crustacean Species Discovered in Atacama Trench

The Atacama Trench stretches along the eastern South Pacific Ocean, plunging to depths exceeding 8,000 m off the coast of northern Chile.

The hadal zone, or the deepest 45% of the ocean (6,000-11,000 m), has high levels of undiscovered biodiversity.

Most hadal features are trenches formed at the subduction zone between tectonic plates and shaped by a unique suite of extrinsic and intrinsic factors.

The Atacama Trench, or the Peru-Chile Trench, is one of the most geographically isolated hadal features and is situated below eutrophic surface waters and characterized by high sediment loads.

This trench is known to host a highly distinctive faunal community, driven by a combination of these isolating factors.

“The deep ocean is a vast reservoir of new species to science, and each discovery improves our ecological understanding of these remote ecosystems,” said Woods Hole Oceanographic Institution researcher Johanna Weston and colleagues.

“One island-like ecosystem is the Atacama Trench, where the hadal depths (over 6,000 m) host a distinctive endemic community.”

“Unlike the communities of other hadal subduction trenches, predatory (non-scavenging) amphipods have not been documented or collected from the Atacama Trench.”

The newly-discovered species, Dulcibella camanchaca, is the first large, active predatory amphipod from these extreme depths.

At nearly 4 cm in length, this crustacean uses specialized raptorial appendages to capture and prey upon smaller amphipod species in the Atacama Trench’s food-limited realm.

“Most excitingly, the DNA and morphology data pointed to this species being a new genus too, emphasizing the Atacama Trench as an endemic hotspot,” Dr. Weston said.

The discovery was made during the 2023 Integrated Deep-Ocean Observing System (IDOOS) Expedition aboard the R/V Abate Molina.

Four Dulcibella camanchaca individuals were collected at a depth of 7,902 m using a lander vehicle, which is an untethered platform used for carrying scientific equipment, including baited traps, to and from the ocean floor.

“This study’s collaborative effort and integrative approach confirmed Dulcibella camanchaca as a new species and highlight ongoing biodiversity discoveries in the Atacama Trench,” said Dr. Carolina González, a researcher at the Instituto Milenio de Oceanografía.

“This finding underlines the importance of continued deep-ocean exploration, particularly in Chile’s front yard.”

“More discoveries are expected as we continue to study the Atacama Trench.”

The discovery is reported in a paper in the journal Systematics and Biodiversity.

_____

Johanna N.J. Weston et al. 2024. A new large predator (Amphipoda, Eusiridae) hidden at hadal depths of the Atacama Trench. Systematics and Biodiversity 22 (1): 2416430; doi: 10.1080/14772000.2024.2416430