Internship in study of the spatio-temporal variability of micronekton distribution in the tropical Atlantic, in relation to their abiotic environment, using acoustic data acquired during the PIRATA surveys

For more than 20 years, cruises were performed annually in the eastern tropical Atlantic to deploy and maintain the buoys of the PIRATA (‘Prediction and Research moored Array in the Tropical Atlantic’; Bourlès et al., 2008) program. The number of sampling instruments and measurements increased throughout the years, providing comprehensive datasets of the biological and environmental variability in this region. Since 2015, annual surveys were carried out aboard the research vessel Thalassa, equipped with echosounders (https://www.seanoe.org/data/00602/71379/). This has enabled to add a biotic component to this exceptional time series of data on the abiotic environment. Over the last 10 years, the densities and vertical distribution of micronektonic organisms can be monitored in relation to environmental parameters. The micronekton includes a wide variety of species measuring from 2 to 20 cm in length (fish, crustaceans, squid, gelatinous organisms). They form an essential part of the biotic environment, in all oceans, as it is the source of food for large predators such as tuna, seabirds and marine mammals. Some of them migrate vertically every day from the great depths where they live during the day to escape predators, to the surface where they come at night to feed on zooplankton.