NAUTILOS Depth, Temperature, Dissolved oxygen and Chlorophyll-a dataset collected by Fishing Vessels, CNR IRBIM AdriFOOS platform in the Adriatic Sea

The NAUTILOS H2020 project aims to fill existing gaps in marine observation and modelling through the development of new technologies and their deployment on different observational platforms. One of the specific objectives of the project is to promote innovative and cost-effective methods in a wide range of critical environmental contexts and European Union policy applications as for example the Marine Strategy Framework Directive (Directive 2008/56/EC) and the Common Fisheries Policy (EU REGULATION 1380/2013). Based on the experience of the CNR-IRBIM Adriatic Fisheries and Oceanography Observing System (AdriFOOS; Penna et al. 2023) and the Ifremer RECOPESCA ( Duchêne et al. 2023) programs, a new generation of sensors has been designed, implemented and tested within NAUTILOS to collect measurement of Essential Ocean Variables (EOVs) by exploiting the capacity of commercial fishing vessels as emerging platforms for ocean observation (Van Vranken et al. 2023). Data produced for the Adriatic Sea (Mediterranean basin) from 2003 to 2013 through this approach have proven useful for feeding oceanographic models and expanding knowledge on climate change, as well as improving the ecosystem approach to fisheries management (Carpi et al. 2015; Russo et al. 2015; Aydoğdu et al. 2016; Russo et al. 2016; Lucchetti et al. 2018). As part of NAUTILOS NKE Instrumentation developed prototype sensors for measuring Dissolved Oxygen (DO) and Chlorophyll a (Chl-a), designed specifically for use in fisheries and aquaculture applications. Each sensor also measures depth and temperature and communicates via Wi-Fi with an automatic data recovery and transmission system (WiHub), which also records the Global Positioning System (GPS) track. Prototypes were factory calibrated respectively for DO and Rhodamine WT and the sensor specifications declared by the manufacturer are reported in NAUTILOS Deliverable 7.1. The prototypes underwent laboratory calibrations at the Ifremer, CNR and SYKE facilities and subsequent field validation tests in the North Sea, the Adriatic Sea, the Baltic Sea and the Bay of Biscay reported in NAUTILOS Deliverable 5.6. Tests included comparisons with traditional oceanographic instruments, measurements at different salinity/temperature/dissolved oxygen combinations, and comparative experiments with fluorescein and algal cultures. After that, to improve the "Fisheries Observing Systems" approach, the sensors were demonstrated by CNR-IRBIM in the Adriatic Sea and by Ifremer in the Bay of Biscay. In detail, a bottom trawler based in the port of Ancona was selected to participate in NAUTILOS demonstrations. The vessel was already part of the AdriFOOS architecture. This type of fishery allows the sensors to be installed directly on fishing gear deployed at sea and dragged along the seabed (namely on the otter doors), normally at constant speed and stable depth. Otter doors also provide good support for installing sensors and some degree of protection. This configuration offers adequate operational conditions for the DO and Chl-a sensors. From July 2023 to February 2025, CNR-IRBIM staff constantly monitored the functioning of the deployed DO and Chl-a prototypes and the Near Real Time data transmission from the sensors installed on the fishing gear operating in the Adriatic Sea to the NAUTILOS web services. The acquisition (and for the DO sensor also the internal salinity) settings used for the sensor deployment are described in NAUTILOS Deliverable 7.1 and 7.2. Data to which the AdriFOOS embedded scripts assigned Data with Quality Control (QC) flags set to 4 (=bad), according to the L20 standard vocabulary in Seadatanet, were not delivered. The full data stream from the fishing vessel toward the NAUTILOS ERDDAP™ is as well described in NAUTILOS Deliverable 7.1. The obtained dataset was ingested into EMODnet, under the Physics theme. A full metadata description is available in the NAUTILOS ERDDAP™. In March 2023, the previously produced dataset was further verified and analyzed by CNR IRBIM specialized staff to ensure the quality of the records; a visual inspection was carried out by means of Ocean Data View (ODV) following the procedure described in Penna et al. 2023. The dataset here presented corresponds to a subset of validated data collected via the AdriFOOS infrastructure using the NKE Instrumentation DO 2222 and Chl-a 8888 prototypes from July 2023 to December 2024, and consists in 471587 data points recorded along 3968 fishing hauls carried out in the Central Adriatic Sea. The entire demonstration activity carried out in the Adriatic Sea and the results obtained are described in the NAUTILOS Deliverable D7.2. The collected data proved useful for detecting transient and exceptional events that occurred (e.g. extreme temperatures and mucilage events).