Marine growth has been observed to cause a drop in the horizontal and vertical velocities of underwater gliders, thus making them unresponsive and needing immediate recovery. Currently, no strategies exist to correctly identify the onset of marine growth for gliders and only limited datasets of biofouled hulls exist. Here, a field test has been run to investigate the impact of marine growth on the dynamics of underwater gliders. A Slocum glider was deployed first for eight days with drag stimulators to simulate severe biofouling; then the vehicle was redeployed with no additions to the hull for a further 20 days. The biofouling caused a speed reduction due to a significant increase in drag. Additionally, the lower speed causes the steadystate flight stage to last longer and thus a shortening of mission duration. As actual biofouling due to p. pollicipes happened during the deployment, it was possible to develop and test a system that successfully detects and identifies high levels of marine growth on the glider using steady-state flight data. The system will greatly help pilots re-plan missions to safely recover the vehicle if significant biofouling is detected.

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Marine growth has been observed to cause a drop in the horizontal and vertical velocities of underwater gliders, thus making them unresponsive and needing immediate recovery. Currently, no strategies exist to correctly identify the onset of marine growth for gliders and only limited data sets of biofouled hulls exist. Here, a field test has been conducted to first investigate the impact of marine growth on the dynamics and power consumption of underwater gliders and then design an anomaly detection system for high levels of biofouling. A Slocum glider was deployed first for eight days with drag stimulators to imitate severe biofouling; then, the vehicle was redeployed with no additions to the hull for further 20 days. The mimicked biofouling caused a speed reduction due to a significant increase in drag. Additionally, the lower speed causes the steady-state flight stage to last longer and the rudder to become less responsive; hence, marine growth results in a shortening of deployment duration through an increase in power consumption. As actual biofouling due to p. pollicipes occurred during the second deployment, it is possible to develop and test a system that successfully detects and identifies high levels of marine growth on the glider, blending model-and data-based solutions using steady-state flight data. The system will greatly help pilots replan missions to safely recover the vehicle if significant biofouling is detected.

PERSEUS (Protection of European Borders and Seas Through the Intelligent Use of Surveillance) was selected as a demonstration project in the FP7 Security call FP7-SEC-2010-1. Its goals were to define and demonstrate a European concept for maritime surveillance systems and to deploy it across the Mediterranean and Atlantic Ocean. The systems were set to operate in a real-life environment by exercising a comprehensive set of maritime surveillance cross-border scenarios between 2013 and 2015. During its 4.5 years, it involved 32 partners from 12 countries with a budget of 42M€. PERSEUS is set in the EUROSUR policy context. EUROSUR is the information exchange framework designed to improve the management of Europe's external borders. It aims to support member states by increasing their situational awareness and reaction capability in combating cross-border crime, tackling irregular migration, and preventing loss of migrant lives at sea. However, it also is in the reality of the existing national and regional systems operated by each member state to monitor its own maritime space. The PERSEUS project delivered successful results in three different domains. Some of them are a validated solution enabling shared surveillance of maritime borders (operational); an architecture, domain, target vision, and processes contributing to EUROSUR (integration); and recommendations and lessons learned toward evolving collaborative maritime surveillance policies (best practices). The line followed by PERSEUS using autonomous maritime surveillance systems such as the Wave Glider (<ext-link ext-link-type="uri" href="http://www.liquidr.com">http://www.liquidr.com</ext-link>) opens new research lines for future collaboration opportunities.

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