IJL TAPIOCA: A collaborative French-Brazilian initiative to advance biodiversity and taxonomic knowledge of deep-pelagic fishes

Deep-pelagic ecosystems (below 200 meters depth) encompass thousands of species intrinsically linked to critical ecosystem processes, such as carbon sequestration and the connectivity between pelagic layers and trophic levels. However, deep-pelagic realms remain some of the least explored ecosystems globally and is increasingly imperiled by human activities. This challenge is particularly acute for developing nations, where participation in deep-sea research is hampered by limited expertise, lack of incentives, and restricted access to advanced technological infrastructure, leading to an almost complete absence of knowledge regarding their deep-pelagic biodiversity. Here, we present a case study of international cooperation that serve as a model for advancing knowledge of deep-pelagic fish diversity in historically understudied regions. The International Joint Laboratory – Tropical Atlantic Interdisciplinary Laboratory on Physical, Biogeochemical, Ecological, and Human Dynamics (IJL TAPIOCA) exemplifies this collaborative model. This consortium brings together a multidisciplinary team of researchers and students from the French Institut de Recherche pour le Développement (IRD) and several Brazilian institutions, including the Federal Rural University of Pernambuco (UFRPE) and the Federal University of Rio de Janeiro (UFRJ). One of the main goals of the consortium is to deepen understanding of the biodiversity and distribution of deep-sea fishes from off northern and northeastern coasts of Brazil, a region with limited baseline data on species diversity. Focusing on deep-pelagic fish diversity, recent expeditions have explored two different areas: the Fernando de Noronha Ridge (including the Fernando de Noronha Archipelago, Rocas Atoll, and nearby seamounts) and the oceanic waters in front of the Amazon River estuary. Through these expeditions, a remarkable diversity of deep-sea fishes was documented, with collections totaling around 15,000 fish specimens, representing approximately 250 nominal species, 60 of which represent new distribution records in Brazilian waters. Furthermore, at least 12 new species have been identified so far, including notable discoveries in the genera Eustomias, Melanosthomias, Astronesthes (Stomiiformes), Poromitra and Melamphaes (Beryciformes). The specimens and selected tissue samples were deposited at the Fish Collection of the Institute of Biodiversity and Sustainability (NUPEM/UFRJ). All data are available online at two repositories: https://specieslink.net and https://www.sibbr.gov.br. These findings not only enhance the knowledge of mesopelagic fish diversity in poorly studied areas but also provide important insights into species distribution patterns and the biodiversity of deep-sea ecosystems. This research underscores the significance of international collaboration in addressing pressing questions related to marine biodiversity and conservation, especially in underexplored regions.