Talud Continental IV
12 July – 31 July 2025
#MarDelPlataCanyon
Two powerful currents converge in the Mar del Plata Submarine Canyon in Argentina’s Exclusive Economic Zone. One is warm and salty; the other is nutrient-rich and cold. Together, they form the Brazil-Malvinas Confluence, one of the most energetic regions in our global Ocean. These currents help to redistribute heat from the tropics to the poles and play a prominent role in the Earth’s climate. While scientists know these currents support submarine canyon ecosystems, their effects have never been visualized. This expedition will explore the diversity and distribution of seafloor communities in one of the country’s largest deep-sea canyons.
In 2012 and 2013, Argentinian scientists conducted a series of expeditions in this region using fishing nets and trawls. With these low-tech tools, they discovered new species and published more than 60 papers. Their research allowed many students to launch their marine biology careers. Even without access to state-of-the-art technology, these earlier expeditions provided evidence of cold-water coral that hosts abundant fish and invertebrates. Yet, the distribution of these ecosystems within the canyon and their ecosystem structures remains poorly understood. Using ROV SuBastian, the scientists will make the first in situ observations of this massive seafloor feature and document the biodiversity it harbors. The expedition — led by Dr. Daniel Lauretta of Museo Argentino de Ciencias Naturales Bernardino Rivadavia – CONICET, Argentina — will establish a strong foundation for future research, conservation, and resource management.
Where two currents collide
The Malvinas Current moves northward from Antarctica along the continental shelf of Argentina and ends near the Río de la Plata. This current is a branch of the Antarctic Circumpolar Current; it draws cold, nutrient-rich waters northward from Antarctica to the Patagonia shelf. Extending from the sea surface to the seafloor, the current fuels the entire water column along the coast of Argentina and sustains the country’s fishing industry, which was valued at almost $2 billion USD in 2024.
The Brazil Current is a surface current that does not extend to depths greater than 700 meters; it carries warm, salty water from the Equator towards the Río de la Plata.
The Malvinas-Brazil Confluence, where these two currents collide, results in a strong thermocline— a distinct layer formed by temperature and salinity differences. The thermocline generates numerous small swirling currents, or eddies, and facilitates a massive redistribution of heat that helps regulate Earth’s climate.
The confluence likely creates a pronounced biogeographic boundary, facilitating conditions that support high levels of marine biodiversity. On the northern side of the border, there are likely to be more tropical, warm-water species, while on the southern side, the conditions favor temperate, cold-water species. The mixing of these two very different water masses likely creates conditions that facilitate the coexistence of both temperate and tropical organisms, as well as species that may only be found in the confluence.
The Mar del Plata submarine canyon, one of Argentina’s largest and deepest underwater canyons, is estimated to be deeper than 3500 meters or more than two miles below the ocean surface. It cuts into a massive continental shelf off Argentina’s coastline called the Patagonia Shelf, with an estimated area of 1.2 million square kilometers, equivalent in size to South Africa.
Because of the massive shelf, Argentina’s coastal environment is relatively shallow, and the canyon is far from land, serving as a connection between the continental slope and the abyssal plane.
Tools for revealing biodiversity & human impact
This 20-day expedition is the first opportunity for Argentinian scientists to use Falkor (too)’s suite of labs, sonars, landers, and scientific-class ROV to map and visualize the deep seafloor of the Mar del Plata Canyon.
A crustacean and zooplankton trap will be integrated onto the ship’s lander to assess plankton and amphipod populations, aiming to study the diversity and distribution of scavenging species in the canyon, as they are very small and difficult to detect or capture with the ROV. This research will help us better understand ecological connectivity and how these organisms interact with their environment.
They will collect environmental DNA samples via an eDNA sampler integrated onto SuBastian. Evidence of the presence of animals left behind via shed skin and other genetic material allows scientists to assess what animals live in the environment, even if they cannot directly observe them.
Core samples will allow scientists to examine sediments to assess carbon cycling and marine debris. The canyon lies off shore of the Buenos Aires Province, the largest and most populated region in Argentina, with more than 17 million people. The science team anticipates documenting marine debris and plastic pollution in the canyon.
Most important to the science team, ROV SuBastian will enable them to visualize the seafloor and its inhabitants, providing evidence of coral gardens and animal communities they know exist but have never seen in their natural setting, and likely discovering many new species in the area that have never been recorded before.
