Scientific specifications, common and complementary developments for deep sea and coastal fixed point multidisciplinary cabled observatories

The developments of subsea observatories has been addressed by several national and European projects involving Ifremer engineering teams during the last decade. The motivation of scientific research disciplines has been growing during the same period. The coordination of ESONET Network of Excellence has been a unique occasion to analyse the best practices world wide and propose standards and recommendations. The merger of existing observatories and construction of new deep sea observatories in Europe is now organized at European level through EMSO (European Multidisciplinary Seafloor Observatory). Its preparatory phase is now building a multi-site large research infrastructure. The French participation is planned through the EMSO-France initiative. The need to monitor the sea environment is also acute in the coastal zone as Marine Protective Areas, indicators of marine biodiversity and ecological quality are requested by the marine strategy directives (such as European Marine Strategy Framework Directive). The cost effectiveness of the long term observatories will gain from a choice of common technologies and operating methods for coastal observatories and deep sea networks. Innovative solutions are proposed in the fields of: biofouling protection, sensor web enable interface, sensor registry, data management, material choice, energy requirements, junction box designs,... A review of these solutions is presented in the paper. Coastal cabled observatories such as MeDON are used as test benches for several of these new developments. Even in the cases when depth will induce different technologies, the deep sea cabled and shallow water cabled observatories may be designed in such a way that operating methods will be similar (components, subsea intervention methods, remote maintenance procedures, network management practices, sensor calibration procedures,...). Ifremer engineering teams are using the ongoing projects to enhance reliability in shallow as well as deep wat- - er cabled observatories.