Science1 publisher2 min readPublished
Argentina's Mar del Plata Canyon yields 57 new species from a tenth of its samples
Taxonomists at an Ocean Census workshop found 57 new species and five new genera in a tenth of the samples from Argentina's Mar del Plata Canyon. Whether the canyon is unusually rich depends on what the other 90 percent hold.
The Scientist · Science desk
Drafted by a language model from the sources cited here and checked against its claim ledger before publication. How we use AISend a correction
What happened
- The samples came from an August 2025 expedition to the Brazil-Malvinas Confluence off Argentina, where warm subtropical currents meet cold, nutrient-rich sub-Antarctic water.
- The Mar del Plata Submarine Canyon runs more than 11,000 feet deep, nearly twice the depth of the Grand Canyon.
- The new species comprise 20 copepods, 22 echinoderms, 14 cnidarians such as corals and sea pens, and one scaphopod mollusc.
- Twenty taxonomists and early-career researchers from Latin America and Europe examined the samples at Universidad Maimonides in Buenos Aires.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- decision The next test needs no new cruise, because sorting the 90 percent of samples already collected would show whether the near-total novelty rate holds across the whole haul.
- constraint In groups with few active specialists, unsorted samples move only when those people can be assembled, so progress on the canyon's backlog is limited by taxonomist time.
- contradiction The account calls the species named while hedging the sea cucumbers as potentially 10 and listing two corals only to genus, so some of the 57 are still candidates.
According to Popular Science, the team had examined only 10 percent of the samples collected, and "every specimen was a species new to science" [1]. That sentence sits in the account's paragraph on copepods, so it may describe that group's material more than the whole haul [1]. On either reading, 90 percent of the samples have not yet been examined [13].
The 10 percent is a share of samples. The account does not say how many samples the expedition collected, how many specimens the examined tenth contained, or how that tenth was picked [1]. Those figures decide what a 100 percent novelty rate means. If the first pass went to the animals that looked least familiar, a run of new species is what that choice would produce. Multiplying the 57 species [14] by ten gives about 570 [16]. That number holds only if the unsorted samples are as novel and as varied as the sorted ones.
"The deep sea holds some of the least understood ecosystems on Earth," said Michelle Taylor, Ocean Census' head of science [10]. In my view the count is strong evidence of how little of this canyon's fauna had been described. Ranking the Brazil-Malvinas Confluence as a hotspot would take comparison with other deep sites sampled and sorted with similar effort. A case for protecting it would also need evidence about what threatens it.
Some of the 57 remain provisional in the account's own wording. Loki, a sea cucumber in the genus Peniagone, was found at 2,577 meters and is one of "potentially 10" new sea cucumber species [4]. Two of the new corals, a sea pen and an orange-red octocoral, are listed only to genus, as Pseudumbellula sp. and Orstomisis sp. [5]. The new genera span corals, sea cucumbers and crustaceans [7]. The account says the species were named at a workshop for describing new species, run by the Nippon Foundation-Nekton Ocean Census jointly with the Schmidt Ocean Institute [8].
The limit the scientists describe is specialist time. "Discovering 57 new species and five new genera in just two weeks demonstrates the speed and power of collaborative taxonomy," Taylor said [9]. That is roughly four species a day [15]. "International cooperation in taxonomy is critical, especially in groups with few active specialists," said Daniel Lauretta, a chief scientist with CONICET and the Museo Argentino de Ciencias Naturales [12].
What to watch
- Results from the remaining 90 percent of the Mar del Plata Canyon samples, and whether the share of new species stays near 100 percent once the whole haul is sorted.
- Formal descriptions of the 57, including species names for the corals now listed as Pseudumbellula sp. and Orstomisis sp. and confirmation of the potentially 10 new sea cucumbers.
- Comparable sorted samples from other deep canyons, which would show whether the Brazil-Malvinas Confluence is richer than sites studied with similar effort.