Biosensor technology, in which a biological recognition element is immobilized on a transducer, offers advantages over the traditional analytical methods. Being cost-effective, today?s technology enables these devices to be tailored in field-based automat ed monitoring systems. Biosensor techniques can inexpensively measure a variety of compounds. Quick multi-compound analysis is also feasible. Recent technologies have been used in the detection of target analytes as well as in biological measurements of t oxicity, genotoxicity and estrogenicity. On-line sensors deployed on sentinel organisms can also enable to monitor in situ behavioural and physiological changes and may provide an immediate diagnose of the quality of the marine environment. To date, few l aboratories have attempted to use these techniques at sea. The main objective of this project is to assess the applicability of existing or emerging biosensor technologies and on-line sensors deployed at sea. The project will be divided in several tasks. A selection of relevant biosensors will be made, tested for performance against key target pollutants and optimised accordingly. An attempt to incorporate the selected biosensors in a unique micro-array system combining identification of target pollutant and their biological effects will be pursued. With the view of applying the device in the field, a validation step with current chemical and biological analyses is essential. The actual in situ deployment of the micro-array device will require specific ad aptations like robustness, low power consumption but also capability of automatic storage, data acquisition and advanced communication techniques. Novel on-line sensors with fibre optic communication will be tested on relevant species and correlated with current biological effect measurements. The project will contribute to expand the spectra of environmental research performed at RF-Akvamiljø to new challenging fields.