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Ocean Science An interactive open-access journal of the European Geosciences Union
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Review article
06 Feb 2018
Review status
This discussion paper is a preprint. A revision of the manuscript is under review for the journal Ocean Science (OS).
An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the Eastern Mediterranean. The Cretan Sea component of POSEIDON system
George Petihakis, Leonidas Perivoliotis, Gerasimos Korres, Dionysis Ballas, Constantin Frangoulis, Paris Pagonis, Manolis Ntoumas, Manos Pettas, Antonis Chalkiopoulos, Maria Sotiropoulou, Margarita Bekiari, Alkiviadis Kalampokis, Michalis Ravdas, Evi Bourma, Sylvia Christodoulaki, Anna Zacharioudaki, Dimitris Kassis, Emmanuel Potiris, George Triantafyllou, Kostas Tsiaras, Evangelia Krasakopoulou, Spyros Velanas, and Nikos Zisis Institute of Oceanography, Hellenic Centre for Marine Research, Heraklion, 72100, Greece
Abstract. There is a general scarcity of oceanic observations that concurrently examine air–sea interactions, coastal-open ocean processes, and biogeochemical (BGC) parameters, in appropriate spatiotemporal scales, and under continuous, long-term data acquisition schemes. In the Mediterranean Sea, the resulting knowledge gaps and observing challenges increase, due to its oligotrophic character, especially in the eastern part of the basin. The oligotrophic open Cretan Sea's biogeochemistry is considered to be representative of a greater Mediterranean area up to 106 km2, and understanding its features may be useful on even larger oceanic scales, since the Mediterranean Sea has been considered a miniature model of the global ocean. The spatiotemporal coverage of BGC observations in the Cretan Sea has progressively increased over the last decades, especially since the creation of the POSEIDON observing system, which has adopted a multiplatform-multiparameter approach, supporting BGC data acquisition. The current POSEIDON system's status includes open and coastal sea fixed platforms, a Ferrybox (FB) system, and Bio-Argo autonomous floats, that deliver remotely Chlorophyll-a (Chl-a), O2, pH and pCO2 data, as well as BGC-related physical parameters. Since 2010, the list has been further expanded to other BGC (nutrients, vertical particulate matter fluxes), ecosystem and biodiversity (from viruses up to zooplankton) parameters, thanks to the addition of sediment traps, frequent R/V visits for seawater-plankton sampling, and of an ADCP delivering information on macrozooplankton-micronekton vertical migration (in the epi-, mesopelagic layer). Gliders and drifters are the new, currently under integration to the existing system, platforms, supporting BGC monitoring. Land-based facilities, such as data centers, technical support infrastructures, calibration laboratory, mesocosms, support and give added value to the observatory. The data gathered from these platforms are used to improve the quality of the BGC-ecosystem model predictions, which have recently incorporated atmospheric nutrient deposition processes and assimilation of satellite Chl-a data. Besides addressing open scientific questions at regional and international level, examples of which are presented, the observatory provides user oriented services to marine policy-makers and the society, and is a technological test bed for new and/or cost-efficient BGC sensor technology and marine equipment. It is part of European and international observing programs, playing key role in regional data handling and participating in harmonization and best practices procedures. Future expansion plans consider the evolving scientific and society priorities, balanced with sustainable management.
Citation: Petihakis, G., Perivoliotis, L., Korres, G., Ballas, D., Frangoulis, C., Pagonis, P., Ntoumas, M., Pettas, M., Chalkiopoulos, A., Sotiropoulou, M., Bekiari, M., Kalampokis, A., Ravdas, M., Bourma, E., Christodoulaki, S., Zacharioudaki, A., Kassis, D., Potiris, E., Triantafyllou, G., Tsiaras, K., Krasakopoulou, E., Velanas, S., and Zisis, N.: An integrated open-coastal biogeochemistry, ecosystem and biodiversity observatory of the Eastern Mediterranean. The Cretan Sea component of POSEIDON system, Ocean Sci. Discuss.,, in review, 2018.
George Petihakis et al.
George Petihakis et al.
George Petihakis et al.


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Short summary
Oceanic observations that examine several processes including biogeochemical ones are scarce. In the Eastern Mediterranean (Cretan Sea) the spatiotemporal coverage of such observations has increased with the expansion of the POSEIDON observatory. The observatory addresses scientific questions, provides services to policy-makers and society and serves as a technological test bed. It plays a key role in European and international observing programs, in harmonization procedures and data handling.
Oceanic observations that examine several processes including biogeochemical ones are scarce. In...