Javier Gilabert

Evidence of a planktonic food web response to changes in nutrient input dynamics in the Mar Menor coastal lagoon, Spain

Nutrient input dynamics in the Mar Menor coastal lagoon has recently changed as a consequence of changes in agricultural practises. An interannual comparison of the environmental variables and the planktonic biomass size-spectra was performed between 1988 and 1997. While nitrate concentration was low in 1988, the values in 1997 increased considerably. Since 1995, two alloctonous jellyfish species (Rhyzostoma pulmo and Cotylorhiza tuberculata) occurred in large numbers in summer time and reached peak abundance in summer of 1997. The size-spectra analysis comparison revealed that, in spite of changes in nutrient input that stimulated the growth of larger phytoplankton cells, there were no significant differences in the spectra slope which followed a similar seasonal trend in both years. However, the plankton biovolume considered under the size range compared (between 2 and 1000 μm diameter) was, paradoxically, always lower in 1997. Given that there were higher nutrient levels in 1997, this finding suggest a strong top-down control mechanism of size structure. Gut contents of jellyfishes showed their preference for large diatoms, tintinnids, veliger larvae and copepods, corroborating that size structure in these assemblages can be subject to top-down control. The implication of these results is that the feeding activities of large gelatinous zooplankton (jellyfishes) may play an important role controlling the consequences of eutrophication within the Mar Menor coastal lagoon.

Low-cost AUV based on Arduino open source microcontroller board for oceanographic research applications in a collaborative long term deployment missions and suitable for combining with an USV as autonomous automatic recharging platform

The challenge of extending the autonomy in AUV deployments is one of the most important issues in oceanographic research today. The possibility of maintaining a team of AUV under deployment in a defined area of interest for a long period could provide an additional source of information [8]. All this data in combination with the measures provided by buoys and sea gliders used for slow motion and long range operations will be very valuable. A group of low cost AUVs in alternative automatic switching system navigation-charging operation, could allow a kind of continuous surveying operation. This work is the continuation of the ideas that some of the authors previously presented in the AUV 2010 conference at MBARI [8]. At this conference was proposed the great interest for researching oceanic processes on two areas near Cartagena, Spain: cape Tiñoso and the Mar Menor a shallow coastal lagoon. Both areas require a different research structure configuration because of their opposite characteristics. The Mar Menor is a shallow salty lagoon 20 miles long with 7 m of maximum depth and particular features. This lagoon seems to present a sort of oceanic behavior and can be compared with the major oceans but a minor scale. The second area considered is cape Tiñoso, a very deep area in the Mediterranean Sea where the presence of a self-break provides an interesting potential for the research of the effect of upwelling currents.

Integrated Monitoring of Mola mola Behaviour in Space and Time.

Over the last decade, ocean sunfish movements have been monitored worldwide using various satellite tracking methods. This study reports the near-real time monitoring of fine-scale (< 10 m) behaviour of sunfish. The study was conducted in southern Portugal in May 2014 and involved satellite tags and underwater and surface robotic vehicles to measure both the movements and the contextual environment of the fish. A total of four individuals were tracked using custom-made GPS satellite tags providing geolocation estimates of fine-scale resolution. These accurate positions further informed sunfish areas of restricted search (ARS), which were directly correlated to steep thermal frontal zones. Simultaneously, and for two different occasions, an Autonomous Underwater Vehicle (AUV) video-recorded the path of the tracked fish and detected buoyant particles in the water column. Importantly, the densities of these particles were also directly correlated to steep thermal gradients. Thus, both sunfish foraging behaviour (ARS) and possibly prey densities, were found to be influenced by analogous environmental conditions. In addition, the dynamic structure of the water transited by the tracked individuals was described by a Lagrangian modelling approach. The model informed the distribution of zooplankton in the region, both horizontally and in the water column, and the resultant simulated densities positively correlated with sunfish ARS behaviour estimator (rs = 0.184, p<0.001). The model also revealed that tracked fish opportunistically displace with respect to subsurface current flow. Thus, we show how physical forcing and current structure provide a rationale for a predator’s fine-scale behaviour observed over a two weeks in May 2014.

AUV based multi-vehicle collaboration: Salinity studies in Mar Menor coastal lagoon

Abstract An experiment with different AUVs was carried out in the Mar Menor Coastal Lagoon from October 31 to November 5 in order to measure and assess the influence of the water from the Mar Menor on the adjacent area of the Mediterranean. This was carried out as a result of the meeting held between several institutions from the Iberian Peninsula and EEUU (see Vilanova Marine Science/Robotics Meeting 2010). The experiment was to launch several AUVs at the same time in different zones of the Mediterranean and Mar Menor lagoon. AUVs took salinity data trying to do a coordinated mission during two operative days (November 3 and November 5). Others days of the experiment were used to the vehicles preparation and error correction (November 2 and November 4). This paper presents the steps followed in preparation and operative days with the set of AUVs. This paper presents also the salinity results obtained during these missions.

Communication challenges for dual configuration of ASV and AUV in twinned coordinated navigation

Communications between two autonomous vehicles has been always an important challenge, especially when one of the vehicles is intended for conducting submerged navigation most of its operational time. Underwater communications become in that case the one most common and feasible way for allowing data transferring underneath the sea surface. Considering low cost of the final vehicle as one of the main features in the concept of this project, a low power low-cost acoustic modem initially intended for environmental sensor applications has been adopted. With the purpose of increasing at maximum the energy reservoir, this modem includes among others, self-wake capabilities and directional transmission. The present work continues in the validation of this acoustic device for application in Underwater Unmanned Vehicles (UUV) in multivehicle configurations. Different solutions for solving the problems associated to the difficulty of conducting robust and reliable data transferring by using this device are presented.

A multirobot platform based on autonomous surface and underwater vehicles with bio-inspired neurocontrollers for long-term oil spills monitoring

This paper describes the BUSCAMOS-Oil monitoring system, which is a robotic platform consisting of an autonomous surface vessel combined with an underwater vehicle. The system has been designed for the long-term monitoring of oil spills, including the search for the spill, and transmitting information on its location, extent, direction and speed. Both vehicles are controlled by two different types of bio-inspired neural networks: a Self-Organization Direction Mapping Network for trajectory generation and a Neural Network for Avoidance Behaviour for avoiding obstacles. The systems’ resilient capabilities are provided by bio-inspired algorithms implemented in a modular software architecture and controlled by redundant devices to give the necessary robustness to operate in the difficult conditions typically found in long-term oil-spill operations. The efficacy of the vehicles’ adaptive navigation system and long-term mission capabilities are shown in the experimental results.

Re-construction of an AUV as a platform for oceanographic research and a test bed for implementation of control systems based on neurobiological networks

This work considers the re-design of an autonomous underwater vehicle (AUV) in which an innovative, neurobiological inspired sensorization control system is being implemented. Hardware architecture and sensorization control software are being developed to allow autonomous navigation procedures for submarine vehicles. After the refurbishment of the vehicle and the update of its control system, the ROV is able to load CTD sensors, chlorophyll, turbidity, optical dissolved oxygen (YSI V6600 sonde) and nitrate analyzer (SUNA) together with ADCP, side scan sonar and video camera, in a flexible configuration to provide a water quality monitoring platform with mapping capabilitiesi.