Antonio Angrisano, Silvio Del Pizzo, Salvatore Gaglione, Salvatore Troisi, Mario Vultaggio
Enhanced pseudorange weighting scheme using local redundancy

The absolute positioning is the most common GNSS operational mode, being used, for instance, by ships satellite receivers; it is based on pseudorange measurements and its functional model, relating measurements to unknowns, is well defined. On the other hand the stochastic model, describing the measurement error behaviour, is currently under investigation and could be used to reduce the position errors, by defining a suitable weighting scheme. In signal-degraded scenario, as high density traffic harbours or canals, a weighted approach is especially suited, because the pseudorange accuracies are significantly different, so equally weighting all the measurements would bring to large errors. The redundancy numbers are the diagonal elements of the redundancy matrix and they represent the degree of controllability of the measurements; a large redundancy number corresponds to a well-controlled measurement, while a small one corresponds to a leverage observation, with a high potential to influence the solution. In this work, the redundancy number is proposed as indicator, in addition to the largely adopted signal-tonoise ratio and satellite elevation angle, for defining a weighting scheme, based on the concept of limiting the effect of leverage measurements.

Matias Carandell Widmer, Albert Garcia-Benadí, Joaquín del Río Fernandez
OBSEA, a marine sensor testing site for metrology

Marine sensors needs to be tested in real and controlled environments in order to assure, both, proper functionality of the sensor and good enough measurements. Most of times is not enough testing on the lab. Field tests and an inter-comparison with similar sensors can help instruments manufactures, platform operators and scientist to validate instruments. This abstracts introduce OBSEA (Expandable Seafloor Observatory, www.obsea.es), a permanent underwater cabled seabed observatory located in front of the Catalan’s coast near Barcelona, at 20 m depth. Further, some of the current activities where the observatory is used as a test site for different experiments related with marine sensors metrology are presented.

Luca Panebianco, Silvia Zingaretti, Nicolò Ciuccoli, Corentin Altepe, S. Murat Egi, Fiorenza Micheli, David Scaradozzi
Procedures and Technologies for 3D Reconstruction with Divers of Underwater Archaeological Sites and Marine Protected Areas

Underwater monitoring and exploration actions are fundamental to preserve natural habitats and submerged cultural heritage, but researchers have to face high costs related to technology and staff to carry out researches in this troublesome environment. As a partial solution to these problems, Citizen Science has been incrementally employed by the scientific community but, to effectively make the most of it, it is mandatory to design two components: a genericscenario procedure that describes the steps to perform before, during and after the survey and tailored technologies to acquire, gather, process and visualize the environmental data. In this work, a procedure tested in different underwater missions, that is the enhancement of a precedent one, and technologies that, arranged in a pipeline, carry out all the process from data acquisition to output visualization are presented. The procedure and technology were tested in tailored tests aimed to guarantee the validity of the technologies.

Tina Silovic, Gérald Grégori, Mathilde Dugenne, Melilotus Thyssen, François Calendreau, Thibaut Cossart, Harrie Kools, George Dubelaar, Michel Denis
A new automated flow cytometer for high frequency in situ characterisation of heterotrophic microorganisms and their dynamics in aquatic ecosystems

Heterotrophic microorganisms represent the main consumers and mineralisers of the organic matter in the ocean as well as in inland waters. These organisms are in strong interaction with phytoplankton and higher trophic levels and may react quickly to environmental changes. In contrast with phytoplankton, due to the lack of photosynthetic pigments they do not naturally emit fluorescence, which makes more complex their analysis by flow cytometry, and consequently, their dynamics at short time and spatial scales are poorly documented. To fill this gap and extend high frequency observation capacity of flow cytometry (FC) to heterotrophic microorganisms, an automated staining module was designed and now equips a Cytosense flow cytometer to perform in situ automated sampling and analysis. Here we describe the first results got with this device and demonstrate the capacity of this new FC instrument to analyse heterotrophic prokaryotes dynamics at high frequency. In a successful experiment, this prototype yielded an extensive data set generated by automated analyses run every 2 hours over 7 days in the frame of a mesocosm investigation addressing natural marine communities.

Casotti Raffaella, Balestra Cecilia, Van Dijk Mark, Passarelli Augusto, Sigrist Jürg, Hammes Frederik
Real-Time microbial concentrations by automated on-line flow cytometry for marine coastal monitoring

Marine microbes are ubiquitous and play a fundamental role in shaping the oceans as we know them, through key processes such as photosynthesis and biogeochemical cycles. Their monitoring requires sampling at the correct time and space, since they show high turnover rates and patchy distributions. We have used two on-line flow cytometry systems to monitor marine microbes in the coastal area of the Gulf of Naples, as a proof-of-concept that this technology can represent a useful tool for real-time alert systems of water biological quality. Bacterial and picophytoplankton concentrations are proposed as general indicators of water quality, the first step necessary to assess the effects of changes in environmental conditions, to be followed by in-depth analyses of community composition for presence of pathogens or other indicators. During the survey we could detect hotspots of high bacterial concentrations located in areas of discharges of untreated urban wastes or subject to riverine inputs. In general, bacterial abundances were inversely correlated to salinity, suggesting that they use organic matter of terrestrial origin for their growth. The technological approach used represents a useful and fast method to monitor coastal areas also in the context of the European Directive 2008/56/EC, aimed at assessing and improving European marine waters quality.