Marine environments are threatened by pollution through a variety of activities, both directly and indirectly. The varying types, sources, levels and impacts of pollution in marine environments make it very difficult to develop efficient monitoring tools. In addition, monitoring strategies need to be adapted de-pending on the “use” of the marine environment (e.g., aquafarming, tourism, transport) or for the quality of marine environments as natural ecosystems themselves. The major aim of the BRAAVOO project and its contribution to the Ocean of Tomorrow program (FP7-OCEAN-2013) is to develop innovative solutions for measurement of high impact and difficult to measure marine pollutants. In contrast to classical environmental analytics, which is based on site sampling, ex-situ sample extraction and purification, and high-end sophisticated compound detection, the strategy of BRAAVOO is to provide near real-time in-situ sampling and analysis.

The BRAAVOO concept of near real-time in-situ sampling and analysis is based on the use of three types of biosensors, to enable both the detection of a number of specific marine priority pollutants and also of general biological effects that can be used for early warning. The first type of biosensor uses label-free antibody-based immuno-sensing on innovative nanooptical platforms such as bimodal evanescent waveguides or asymmetric Mach-Zehnder interferometers. The second sensing platform consists of live bacterial “bioreporters,” which produce bioluminescence in response to chemical exposure. Finally, the photosystem II fluorescence of marine algae is exploited to monitor changes induced by toxic com-pounds.

BRAAVOO has rigorously tested the three biosensor systems for their analytical performance, responding to a set of targeted pollutants that include algal toxins, heavy metals, organic compounds related to oil, and antibiotics. To enable low-cost real-time measurements, the three biosensors were miniaturized, multiplexed and integrated into biosensing instruments, which allow simultaneous multianalyte detection. The instruments include the optical elements for biosensor signal generation and readout, the microelectronics for data storage, and specific macro- and microfluidics to expose the biosensors to the aqueous samples or calibration solutions. The modules were tested as stand-alone instruments with manual operation (e.g., sample addition manually), and were integrated in a marine buoy and an un-manned surveying vessel (USV). Integrated sensor instruments could be operated autonomously and remotely, store and transmit data to a remote observer. The performance of the stand-alone biosensors and biosensors in their integrated form was tested at field sites in Italy and Ireland, and was further bench-marked using spiked marine samples with known target compound concentrations. Comparative chemical analytics showed reasonable agreement between the two types of measurements, although limits of detection in biosensor measurements without sample pre-treatment were generally (and not surprisingly) higher than in chemical analytics with extensive sample purification and concentration.

Overall, the developed biosensors and biosensor instruments allow flexible and innovative solutions for marine monitoring in terms of efficiency (sample analysis in hours instead of the days or weeks needed for standard sampling, transport to external labs and subsequent analyses) and cost. Further bench-marking on real samples and sites will be necessary to improve the robustness of the biosensor instruments and protocols, and to validate the biosensors' responses in comparison to classical analytics.