Joaquin del Rio

The new seafloor observatory (OBSEA) for remote and long-term coastal ecosystem monitoring

A suitable sampling technology to identify species and to estimate population dynamics based on individual counts at different temporal levels in relation to habitat variations is increasingly important for fishery management and biodiversity studies. In the past two decades, as interest in exploring the oceans for valuable resources and in protecting these resources from overexploitation have grown, the number of cabled (permanent) submarine multiparametric platforms with video stations has increased. Prior to the development of seafloor observatories, the majority of autonomous stations were battery powered and stored data locally. The recently installed low-cost, multiparametric, expandable, cabled coastal Seafloor Observatory (OBSEA), located 4 km off of Vilanova i la Gertrú, Barcelona, at a depth of 20 m, is directly connected to a ground station by a telecommunication cable; thus, it is not affected by the limitations associated with previous observation technologies. OBSEA is part of the European Multidisciplinary Seafloor Observatory (EMSO) infrastructure, and its activities are included among the Network of Excellence of the European Seas Observatory NETwork (ESONET). OBSEA enables remote, long-term, and continuous surveys of the local ecosystem by acquiring synchronous multiparametric habitat data and bio-data with the following sensors: Conductivity-Temperature-Depth (CTD) sensors for salinity, temperature, and pressure; Acoustic Doppler Current Profilers (ADCP) for current speed and direction, including a turbidity meter and a fluorometer (for the determination of chlorophyll concentration); a hydrophone; a seismometer; and finally, a video camera for automated image analysis in relation to species classification and tracking. Images can be monitored in real time, and all data can be stored for future studies. In this article, the various components of OBSEA are described, including its hardware (the sensors and the network of marine and land nodes), software (data acquisition, transmission, processing, and storage), and multiparametric measurement (habitat and bio-data time series) capabilities. A one-month multiparametric survey of habitat parameters was conducted during 2009 and 2010 to demonstrate these functions. An automated video image analysis protocol was also developed for fish counting in the water column, a method that can be used with cabled coastal observatories working with still images. Finally, bio-data time series were coupled with data from other oceanographic sensors to demonstrate the utility of OBSEA in studies of ecosystem dynamics.

A new tracking system for the measurement of diel locomotor rhythms in the Norway lobster, Nephrops norvegicus (L.)

The Norway lobster, Nephrops norvegicus (L.), is a deep-water burrowing decapod of high commercial value. Diel variations in trawl captures are produced by population rhythms of burrow emergences related to day-night cycles. Rhythms seem to be different in males and females since catches show variations in sex ratios depending on the season. Our hypothesis is that the diel rhythm of activity in this species can be distinguished in three different behavioural sets, the durations of which show gender-related modulation: door-keeping, proximal-, and distal-emergence from the burrow. Our aim is to detail the functioning of a new tracking system allowing the durations of these three behavioural components to be determined. Movement of animals was detected by subdividing aquaria into different zones by means of three rows of infrared-emitting and -receiving photodiodes in which blue light emitters were also integrated for the generation of light cycles. We recorded movement patterns in adult males and females (n=20) exposed to a standard photoperiod regime (i.e., 12 h; monochromatic at 480 nm of 5 lx) over 12 days. Marked diel nocturnal rhythms were reported at all barriers, with activity peaks diffused over the night at the burrow entrance and located at the day-night transition at other barriers (i.e., crepuscular peaks that decreased in the next few hours of darkness). Mean total activity was significantly higher for females than males at the burrow entrance (i.e., door-keeping behaviour). Males had significantly higher activity at other locations (proximal- and distal-emergence behaviours).

A New Laboratory Radio Frequency Identification (RFID) System for Behavioural Tracking of Marine Organisms

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.

Precision timing in ocean sensor systems

This paper discusses the use of the IEEE 1588 standard in ocean observatories. The performance result of prototype implementations of this standard in an Ethernet Marine Sensor Network (MSN) is presented. The performance tests emulate an underwater-cabled observatory with a Master Clock synchronized with GPS, located in an on-shore station, and with underwater instruments requiring high-precision PPS (pulse s−1) signals for synchronization purposes. These signals will be provided to the underwater station by an IEEE 1588 GPS Emulator connected to the observatorys Local Area Network (LAN). The experimental setup emulates the underwater-cabled observatory OBSEA where this technology will be installed due to synchronization requirements of marine instruments such as ocean bottom seismometers.

Ocean Bottom Seismometer: Design and Test of a Measurement System for Marine Seismology

The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal–to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth’s crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

Requirements and approaches for a more cost-efficient assessment of ocean waters and ecosystems, and fisheries management

Development of a new generation of multifunctional sensor systems is underway to address ocean monitoring challenges. These range from more precise monitoring of the marine environment to an improved management of fisheries and, among other things, address improved life cycle cost-efficiency. These advances will be achieved through innovations such as multiplatform integration, greater reliability through better antifouling management and greater sensor and data interoperability. Requirements for the sensors have been refined through surveys and discussions with science and industry users. This paper will describe these developments in the NeXOS project.

Control and acquisition system design for an Expandable Seafloor Observatory (OBSEA)

Design of the control unit for the OBSEA seafloor observatory based on a 32 bit microcontroller with SNMP (Simple Network Management Protocol) communication.

TS-MUWSN: Time Synchronization for Mobile Underwater Sensor Networks

Time synchronization is an important, yet challenging, problem in underwater sensor networks (UWSNs). This challenge can be attributed to: 1) messaging timestamping; 2) node mobility; and 3) Doppler scale effect. To mitigate these problems, we present an acoustic-based time-synchronization algorithm for UWSN, where we compare several message time-stamping algorithms in addition to different Doppler scale estimators. A synchronization system is based on a bidirectional message exchange between a reference node and a slave one, which has to be synchronized. Therefore, we take as reference the DA-Sync-like protocol (Liu et al., 2014), which takes into account nodes movement by using first-order kinematic equations, which refine Doppler scale factor estimation accuracy, and result in better synchronization performance. In our study, we propose to modify both time-stamping and Doppler scale estimation procedures. Besides simulation, we also perform real tests in controlled underwater communication in a water test tank and a shallow-water test in the Mediterranean Sea.

OBSEA an oceanographic seafloor observatory

In this paper is described the different items of a subsea observatory. The control system is constantly monitoring the internal and external components of the observatory detecting operating faults and acting automatically in consequence‥ It will be presented an overview of the information treatment servers structure used in the OBSEA project explaining the chosen topology

Studying the behaviour of Norway lobster using RFID and infrared tracking technologies

Different solutions are presented to study species in laboratory. The proposed designs used infrared and RFID technology to locate and track the species in the zone of analysis, the data is processed to extract information about their activity and behaviour.