Sea Turtles for Ocean Research and Monitoring: Overview and Initial Results of the STORM Project in the Southwest Indian Ocean Olivier Bousquet, Mayeul Dalleau, Marion Bocquet, Philippe Gaspar, Soline Bielli, Stéphane Ciccione, Elisabeth Remy, Arthur Vidard To cite this version: Olivier Bousquet, Mayeul Dalleau, Marion Bocquet, Philippe Gaspar, Soline Bielli, et al.. Sea Turtles for Ocean Research and Monitoring: Overview and Initial Results of the STORM Project in the Southwest Indian Ocean. Frontiers in Marine Science, Frontiers Media, 2020, 7, pp.594080:1-19. 10.3389/fmars.2020.594080. hal-03199889 HAL Id: hal-03199889 https://hal.univ-reunion.fr/hal-03199889 Submitted on 16 Apr 2021 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. 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Distributed under a Creative Commons Attribution| 4.0 International License fmars-07-594080 October 23, 2020 Time: 19:2 # 1 ORIGINAL RESEARCH published: 29 October 2020 doi: 10.3389/fmars.2020.594080 Sea Turtles for Ocean Research and Monitoring: Overview and Initial Results of the STORM Project in the Southwest Indian Ocean Olivier Bousquet1*, Mayeul Dalleau2,3, Marion Bocquet1, Philippe Gaspar4, Soline Bielli1, Stéphane Ciccione3, Elisabeth Remy4 and Arthur Vidard5 1 Laboratoire de l’Atmosphère et des Cyclones, UMR 8105 LACy, Saint-Denis, France, 2 Centre d’Etude et de Découverte des Tortues Marines (CEDTM), Saint-Leu, France, 3 Kelonia, l’Observatoire des Tortues Marines, Saint-Leu, France, 4 MERCATOR-Ocean International (MOI), Toulouse, France, 5 Université Grenoble Alpes, Inria, CNRS, Grenoble INP, Grenoble, France Surface and sub-surface ocean temperature observations collected by sea turtles (ST) Edited by: Juliet Hermes, during the first phase (Jan 2019–April 2020) of the Sea Turtle for Ocean Research South African Environmental and Monitoring (STORM) project are compared against in-situ and satellite temperature Observation Network (SAEON), measurements, and later relied upon to assess the performance of the Glo12 operational South Africa ocean model over the west tropical Indian Ocean. The evaluation of temperature Reviewed by: Clive Reginald McMahon, profiles collected by STs against collocated ARGO drifter measurements show good Sydney Institute of Marine Science, agreement at all sample depths (0–250 m). Comparisons against various operational Australia Fabien Roquet, satellite sea surface temperature (SST) products indicate a slight overestimation of ◦ ◦ ◦ University of Gothenburg, Sweden ST-borne temperature observations of ∼0.1 ± 0.6 that is nevertheless consistent *Correspondence: with expected uncertainties on satellite-derived SST data. Comparisons of ST-borne Olivier Bousquet surface and subsurface temperature observations against Glo12 temperature forecasts [email protected] demonstrate the good performance of the model surface and subsurface (<50 m) Specialty section: temperature predictions in the West tropical Indian Ocean, with mean bias (resp. RMS) This article was submitted to in the range of 0.2◦ (resp. 0.5–1.5◦). At deeper depths (>50 m), the model is, however, Ocean Observation, a section of the journal shown to significantly underestimate ocean temperatures as already noticed from global Frontiers in Marine Science evaluation scores performed operationally at the basin scale. The distribution of model Received: 12 August 2020 errors also shows significant spatial and temporal variability in the first 50 m of the ocean, Accepted: 22 September 2020 Published: 29 October 2020 which will be further investigated in the next phases of the STORM project. Citation: Keywords: biologging, ocean modeling, satellite observation, AniBOS, SCTR, sea turtles, tropical Indian Ocean Bousquet O, Dalleau M, Bocquet M, Gaspar P, Bielli S, Ciccione S, Remy E and Vidard A INTRODUCTION (2020) Sea Turtles for Ocean Research and Monitoring: Overview and Initial Results of the STORM Because sea temperature has a strong influence on climate dynamics and global transport of ocean Project in the Southwest Indian water masses, knowledge and observation of this parameter is fundamental to achieve realistic Ocean. Front. Mar. Sci. 7:594080. forecasts and simulations of the coupled ocean-atmosphere system at all spatial and temporal doi: 10.3389/fmars.2020.594080 scales. In particular, sea surface temperature (SST) is an essential parameter in meteorology and Frontiers in Marine Science| www.frontiersin.org 1 October 2020| Volume 7| Article 594080 fmars-07-594080 October 23, 2020 Time: 19:2 # 2 Bousquet et al. Sea Turtles for Ocean Research and Monitoring oceanography, especially in tropical regions, where it plays a to the collection of ocean observations. In this regard, major role in the formation of tropical low-pressure systems, and animal-borne observations do not only provide unique and more generally, ocean-atmosphere interactions. essential ocean data, but also have a positive impact on In recent decades, the international community has developed empowerment. Among the numerous marine candidate species the Global Ocean Observing System (GOOS, Zhang et al., 2009), available, air-breathing diving predators such as elephant seals which has subsequently been integrated into the Global Climate (Cazau et al., 2017) have been considered the most attractive Observing System (GCOS). Resulting satellite measurements animals so far because of their mobility (wide migration), have significantly improved the space-time coverage of ocean their large size (allowing them to be equipped with accurate observations, contributing to the reduction of sampling and geolocation and environmental sensors), and their ability to other random errors in sea surface temperature (SST) analyses. dive deep and frequently in the ocean (to collect numerous However, these measurements remain subject to significant biases hydrographic profiles). Observations collected by elephant that need to be corrected by drifting or moored buoys to seals have been distributed for many years by the French minimize systematic errors in data analyses (Zhang et al., 2006). Observation Service Mammifères marins Echantillonneurs du In the equatorial zone, the Research Moored Array for Milieu Océanique (MEMO), which subsequently joined the African-Asian-Australian Monsoon Analysis and Prediction international consortium Marine Mammals Exploring the Oceans (RAMA) network (McPhaden et al., 2009), which comprises Pole to Pole (MEOP, Roquet et al., 2014). These data are regularly about 40 moored buoys spread along the tropical belt, is a key exploited by MERCATOR-Ocean, the United Kingdom MET- element of the GOOS observing system. RAMA buoys effectively Office and the European Centre for Medium-Range Weather complement the network of surface drifting buoys deployed in Forecasts (ECMWF) to improve ocean forecasting (through data the tropics by collecting temperature and salinity measurements assimilation) and monitor the state of the oceans, particularly in down to 500 m depth. The advent, in the early 2000s, of the polar gyres (Roquet et al., 2013). A drawback of this well- the Argo profiling network (Davis et al., 2001), consisting of known biologging application is that elephant seals only evolve drifting bathymetric sounders that routinely descend to 2,000 in high latitude areas, which excludes the possibility of making m, is another major step forward in sampling the surface and such measurements in tropical or mid-latitude regions. Another subsurface properties of the oceans worldwide. With more than limitation, which nevertheless applies to all marine animals, is 3,800 systems from 30 different contributing countries as of July that collected measurements are solely made on the basis of 2020, the ARGO network has thus become not only the world’s the animals’ journeys and cannot be precisely based on pre- main source of knowledge for oceanographic studies, but also the planned sampling strategies. This drawback can nevertheless be main source of data for calibrating and verifying temperature, overcome by increasing the number of equipped animals in order salinity and velocity fields derived from satellite observations and to maximize the chances of sampling a given area. numerical ocean model predictions. The use of other marine animal species for collecting ocean Although the ARGO and RAMA networks have significantly data is attracting increasing interest from the international improved the density and quality of measurements in the tropical scientific community. For example, March et al.(2020) have oceans, their coverage is not uniform and not always optimized recently explored the possibility of integrating measurements for short- and medium-term applications. The sampling made by various marine animals (e.g., fish, cetaceans, turtles, frequency of ARGO drifters (1 profile every 10 days on average) penguins, etc.) into global ocean observing networks. While is, for instance, rather low and the spatial resolution of the elephant seals, and more generally pinnipeds, appear to be RAMA network (5–15◦ zonal resolution) is quite loose, especially well-suited to