A Tale of Two Submarine Canyons

Understanding currents, canyons, and productivity
All living organisms require fuel for survival. In the Ocean, the base of the food web is primary producers known as phytoplankton, tiny aquatic plants suspended in the water. Primary productivity, simply put, is the creation of organic material from inorganic compounds. At the ocean surface, this productivity is driven by the sun through photosynthesis.

The Malvinas Current extends from the Ocean’s surface to the seafloor and is made up of multiple different water masses. When cold, nutrient-rich waters from the Antarctic Circumpolar Current reach the waters offshore of Argentina, the different water masses mix, feeding massive phytoplankton blooms. This mixing happens year-round but is most pronounced in austral spring. Some blooms are so large they span hundreds of square kilometers, making them visible from space. The primary production from these blooms supports invertebrates, fish, marine mammals, seabirds, and myriad other species; these nutrient-rich waters also sustain a globally important and lucrative fishing industry. Phytoplankton also play a crucial role in capturing CO2 and producing oxygen.

The science team suspects that underwater canyons dramatically influence the Malvinas Current along the northern Bonaerense and southern Patagonian shelf-break, the boundary where the continental shelf — a gently sloping, submerged portion of a continent — abruptly ends and descends into a steeper slope that connects to the seafloor. Argentina’s continental shelf is massive, with an abrupt transition into the slope where the depth changes from about 200 to 4000 meters.

Instead of flowing swiftly northeast along the deeper slope, the current is deflected onto the shallower continental shelf, turning northwest. On the shelf, the current encounters slower-moving sub-Antarctic shelf waters, which are warmer, less salty, and contain fewer nutrients. Essentially, these canyons act as disruptive conduits, breaking down the natural barrier between the shelf and slope waters. This deviation leads to enhanced mixing and turbulent conditions over the shelf, crucially boosting plankton blooms.

Tools for telling the tale
Like most Schmidt Ocean Institute expeditions, the work begins with mapping. The canyons along the shelf-break are only partially mapped, and the relationship between their shape, water masses, sedimentary processes, and biodiversity is not fully understood. The science team will focus on two submarine canyons: one in the Bahía Blanca region and the other in the Almirante Brown region. Multibeam echo sounders, paired with a sub-bottom profiler, which relies on low-frequency acoustic signals, or sound waves, will provide researchers with high-resolution maps of the seafloor, sediment, and rock layers beneath the seafloor.

The ship’s CTD & rosette, outfitted with a Lowered Acoustic Doppler Profiler, or LADCP, will collect water samples and data on properties within the water column, including measurements of the speed and direction of the currents at each station. The researchers will also deploy a range of technologies, including surface drifters, an autonomous glider, landers, net tows, and a moored buoy. These instruments will collect data on current speeds, properties in the water column, meteorological influences, biomass, biodiversity, and more, to fully characterize the behavior of the Malvinas Current at the submarine canyon heads. A series of dives with ROV SuBastian will add imagery and samples to the dataset collected.

Artist-at-Sea
Visual artist Christine Laquet, from Nantes, France, will join the expedition as the Artist-at-Sea. Her work employs multiple types of productions to draw connections across different time periods, unraveling configurations of power and examining the phenomenon of fear. She investigates how we relate to our environment by focusing on nonhuman elements (such as animal figures, plants, or minerals) as well as invisible influences, employing a poetic process of reorganization to seek new perspectives across geological timescales.

Combined with a research-based approach and situated in the context of the Anthropocene, her work aims to bridge the gap between the viewer and the participant, as well as the farthest reaches of space and time. Through graphic, performative, and installation works, she seeks to challenge our gaze and change our points of view.

Christine has exhibited her work internationally in notable institutions such as the Contemporary Art Museum A. Magalhaes (BR), at the PyeongChang Biennale (KR), the Zamek Culture Center (PL), or the BUG gallery (TH) amongst others, in France and from New York to Bangkok, Innsbruck, Poznan, Sao Paolo, Seoul, and Aarhus.