NeXOS Project Takes Aquatic Sensors to Next Level

Earthzine2017 Monthly Focus Topic, Themed Articles

NeXOS project helps us look at the ocean, listen to the ocean, and understand the ocean from a fish’s point of view.

The NeXOS project, which ends in September 2017, is a multi-year, multi-team undertaking that developed and demonstrated 10 interoperable “plug-and-play” sensors applicable in a multitude of aquatic environments. The project was coordinated by the Oceanic Platform of the Canary Islands (PLOCAN), and has partners across Europe.

The four-year project created multifunctional sensor systems that are innovative, compact, and cost effective with new capabilities for anti-fouling and data management. These sensor systems can be deployed from fixed platforms or by mobile and autonomous platforms, which broadens their applicability. Four of the sensors are featured in this series of articles published by IEEE Earthzine.

A key goal of the project is to sustain the NeXOS advances by making the sensors commercially available to the observation and regulatory communities. The overarching goals of the project are to look at the ocean, listen to the ocean, and understand the ocean as the chemistry, biology, and physical processes of the oceans change. There are many factors necessary to build a new and sustainable capability. These include:

  • Delivering cost-efficient multifunctional sensors  
  • Implementing a common data and sensor interface so sensors can be quickly integrated into platforms
  • Improving sensor reliability to support long term sustained operation
  • Making diverse data more accessible by having data in a standard format
  • Increasing the data availability in near real time by reducing the need for human-operated quality control.

The project partners this year demonstrated the optical and acoustic sensor systems in the central and north Atlantic on mobile and fixed platforms, and demonstrated the ecosystem approach to fisheries (EAF) sensor system and passive acoustics in the North Sea and Mediterranean Sea.

The first three of these sensors, the MatrixFlu-UV, MatrixFlu-VIS and MiniFlu, are small, low-power multifunctional optical sensors systems that use multi-wavelength fluorescent technology to detect colored dissolved organic matter (CDOM) through fluorescence spectroscopy. This technique directs ultraviolet light through a water sample, and the spectra of light emitted  by a dissolved substances in response to the illumination is used to identify it. A technique typically used in laboratory settings, the MatrixFlu sensors take measurements in the water. These sensors can detect the presence and magnitude of multiple types of dissolved matter simultaneously as well as the presence of chlorophyll In microscopic plankton. Operating on the visible light spectrum, MatrixFlu sensors monitor CDOM levels, polycyclic aromatic hydrocarbons (PAH), and turbidity. The MiniFlu is used to detect hydfrocarbons in the ocean.

The bench-top version of the hyperspectral absorption cavity sensor in the silver box sits beside a small black tube (between silver box and computer), which is the commercially available version of the sensor. Image Credit: Jochen Wollschläger

When the density of elements to be measured is not high, an alternative system uses an integrating cavity to increase sensitivity. The sensor is called a hyperspectral cavity absorption sensor. It uses the highly reflective interior of the sensor cavity to give multiple passes through the media being measured. In NeXOS, the sensor monitors organics, including numerous phytoplankton species present in ocean water. By measuring the amount of light absorbed and scattered by phytoplankton, the sensor aids scientists in determining phytoplankton life cycles, CDOM levels, and could indicate the likelihood of harmful algal blooms. The hyperspectral cavity absorption sensor can be deployed in situ for long times because of built-in calibration capabililties.

A NeXOS acoustic sensor to monitor ocean sounds. Image Credit: Eric Delory

Sounds in the ocean are another area addressed by the European Marine Sustainability Framework Directive looking at the needs of marine sustainability. Using a special signal processing board joined with state of the art hydrophones, NeXOS created two types of passive acoustic sensors capable of capturing very low frequencies, like right whales and earthquakes, to high frequencies, such as those of bottlenose dolphins. Additionally, passive acoustic sensors are used to set a baseline of human-caused underwater noise from shipping traffic, construction, and so on.

A third group of sensors expands on the RECOPESCA project by providing new measurements of oxygen and chlorophyll where fishing nets are deployed. This adds to the data for temperature, pressure and salinity that are already part of the program. All of this is part of an ecosystem approach to fisheries (EAF). Field demonstrations were run in Norway and Italy in addition to the work in France.

Though ocean sensor technology has been improving, the inability of the sensors to work across diverse operating systems, among other challenges, has plagued ocean research. A key component of the NeXOS project is the interoperability of the sensors. All NeXOS sensors are web-enabled, and this allows the data to be disseminated to multiple computer platforms.

The contributions of the project include presentations to the science and marine communities at international meetings such as IEEE Oceanic Engineering Society/Marine Technological Society Oceans conferences, European Geosciences Union, Group on Earth Observations-related meetings, American Geophysical Union Ocean meetings, as well as demonstrations in the summer of 2017. Additionally, the inter-cooperation effort between NeXOS and the other projects funded under the OCEANS 2013.2 call led to joint demonstrations and presentations at Oceanology International, initiation of a data interoperability working group, and adoption of common standards and practices.

Project partners were PLOCAN (Spain), IFREMER (France), Uni-HB (Germany), 52North (Germany), AMU (France), UPC (Spain), ALSEAMAR (France), UNOL (Germany), NKE (France), TrIOS (Germany), CMR (Norway), CTN (Spain), HZG (Germany), REC (Norway), NIVA (Norway), SMID (Italy), FRANATECH (Norway), UniRESEARCH (Norway), CNR-ISMAR (Italy), IEEE (France), ECORYS (Netherlands). NeXOS was funded by the European Commission (Grant Agreement No. 614102) under the call FP7-OCEAN-2013.2 from the EU Commission as part of the 7th Framework Program, “The Ocean of Tomorrow” topic.

The ultimate goal of the NeXOS project is to protect the marine resources and associated economic and social activities, as well as manage anthropogenic effects on the marine environment for greater protection and sustainable use.

This is an introduction to a series of articles that detail the sensors and discuss their important impacts on aquatic Earth observations. Other articles in the series are below: 

This article was funded in part by the NeXOS project by Grant Agreement No. 614102 under the call FP7-OCEAN-2013.2 from the European Commission.

Kelley Christensen is Earthzine’s science editor. Follow her on Twitter @kjhchristensen.