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The study of the effects of climate change on the marine environment requires the existence of sufficiently long time series of key parameters. The study of these series allows both to characterize the range of variability in each particular region and to detect trends or changes that could be attributed to anthropogenic causes. For this reason, networks of permanent cabled observation systems are being deployed in the ocean. This paper presents a balance of a decade of activity at the OBSEA cabled observatory, as an example of ocean monitoring success and drawbacks. It is not the objective of this article to analyze the scientific and technical aspects already presented by the authors in different publications (Table 4). We will evaluate the overall experience by retracing the different steps of infrastructure deployment and maintenance, focusing on routines for in situ control, damages experienced, breakdowns and administrative constraints by local administrations. We will conclude by providing a set of guidelines to improve cabled observatories scientific outreach, societal projection, and economic efficiency. As a result of this work, a 10-years dataset has been published in Pangaea that is available for the community. INDEX TERMS Cabled observatories, multidisciplinary observation, coastal ocean monitoring, underwater imaging, european multidisciplinary seafloor and water column observatory (EMSO), JERICO-RI.

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Radio frequency identification (RFID) devices are currently used to quantify several traits of animal behaviour with potential applications for the study of marine organisms. To date, behavioural studies with marine organisms are rare because of the technical difficulty of propagating radio waves within the saltwater medium. We present a novel RFID tracking system to study the burrowing behaviour of a valuable fishery resource, the Norway lobster (Nephrops norvegicus L.). The system consists of a network of six controllers, each handling a group of seven antennas. That network was placed below a microcosm tank that recreated important features typical of Nephrops’ grounds, such as the presence of multiple burrows. The animals carried a passive transponder attached to their telson, operating at 13.56 MHz. The tracking system was implemented to concurrently report the behaviour of up to three individuals, in terms of their travelled distances in a specified unit of time and their preferential positioning within the antenna network. To do so, the controllers worked in parallel to send the antenna data to a computer via a USB connection. The tracking accuracy of the system was evaluated by concurrently recording the animals’ behaviour with automated video imaging. During the two experiments, each lasting approximately one week, two different groups of three animals each showed a variable burrow occupancy and a nocturnal displacement under a standard photoperiod regime (12 h light:12 h dark), measured using the RFID method. Similar results were obtained with the video imaging. Our implemented RFID system was therefore capable of efficiently tracking the tested organisms and has a good potential for use on a wide variety of other marine organisms of commercial, aquaculture, and ecological interest.

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Abstract-on this work a low cost OFDM transmitter for underwater sensor networks is presented. The transmitter is based on a low power microcontroller that governs a DDS in order to generate the output data -OFDM symbols-avoiding the IFFT computations. This solution represents a new design perspective for the current UWSN -mainly based on FPGAs or DSPs, allowing to reduce the cost, the power consumption and the size of the current transmitters.

Abstract:The behavior of crustacean decapods is poorly characterized in artificial reef areas, being of relevance for population management and conservation studies based on capture and release. Acoustic tags were used to study the behavior of 3 adult spiny lobsters (Palinurus mauritanicus) and 3 spider crabs (Maja squinado), evaluating the use of artificial reef areas as suitable sites for re-stocking of overfished decapods. For this purpose, animals were released in a western Mediterranean artificial reef located at 20 m depth, close to a cabled sea-floor observatory (OBSEA). That cabled platform recorded simultaneously temperature, salinity, current direction plus speed, and light intensity close to these structures. The study lasted 64 days and was carried out during summer. Spiny lobster lingered in the reef area, while of the spider crab only remained between 21 and 45 hours. These behavioral differences suggested that artificial reefs might be a good area to deploy adult lobsters for re-stocking purposes. The movements displayed by the lobsters during this experiment were not influenced by any of the measured environmental factors, while spider crab movements took place against current major direction, when speed current was intense. Powered by Editorial Manager® and ProduXion Manager® from Aries Systems Corporation