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Malanotte-Rizzoli, Paola ... et. al.-- 76 pages, The importance of the Mediterranean Sea for the world ocean has long been recognized. First, the Mediterranean sea has a profound impact on the Atlantic ocean circulation and, consequently, on the global thermohaline conveyor belt. Maps of the 5 Mediterranean salty water tongue exiting from the Gibraltar strait at intermediate depths and spreading throughout the Atlantic interior are well known since the 1950s. Through direct pathways to the Atlantic polar regions or through indirect mixing processes, the salty Mediterranean water preconditions the deep convection cells of the polar Atlantic. There the North Atlantic Deep Water is formed which successively spreads throughout 10 the world ocean constituting the core of the global thermohaline circulation. Even more importantly, the Mediterranean Sea is a laboratory basin for the investigation of processes of global importance, being much more amenable to observational surveys because of its location in mid-latitude and its dimensions. Both the western and eastern basins in fact possess closed thermohaline circulations analogous to the 15 global conveyor belt. A unique upper layer open thermohaline cell connects the eastern to the western basin and, successively, to the north Atlantic through the Gibraltar strait. In it, the Atlantic water entering into Gibraltar in the surface layer, after travelling to the easternmost Levantine basin, is transformed into one of the saltiest water masses through air–sea heat and moisture fluxes. This is the salty water which, crossing the 20 entire basin in the opposite direction below the surface Atlantic water, finally exits from the Gibraltar strait at mid-depths. Both the western and eastern basins are endowed with deep/intermediate convection cells analogous to the polar Atlantic deep convection cells or to the intermediate mode water ones. Deep and intermediate water masses are therefore formed in differ25 ent sites of the entire basin. Because of their easily accessible locations, these convection cells are much more amenable to direct observational surveys and mooring arrays

The distribution of the chlorophyll a concentration ([Chl a]) in the Mediterranean Sea, mainly obtained from satellite surface observations or from scattered in situ experiments, is updated by analyzing a database of fluorescence profiles converted into [Chl a]. The database, which includes 6790 fluorescence profiles from various origins, was processed with a specific quality control procedure. To ensure homogeneity between the different data sources, 65 % of fluorescence profiles have been intercalibrated on the basis of their concomitant satellite [Chl a] estimation. The climatological pattern of [Chl a] vertical profiles in four key sites of the Mediterranean Sea has been analyzed. Climatological results confirm previous findings over the range of existing [Chl a] values and throughout the principal Mediterranean trophic regimes. They also provide new insights into the seasonal variability in the shape of the vertical [Chl a] profile, inaccessible through remote-sensing observations. An analysis based on the recognition of the general shape of the fluorescence profile was also performed. Although the shape of [Chl a] vertical distribution characterized by a deep chlorophyll maximum (DCM) is ubiquitous during summer, different forms are observed during winter, thus suggesting that factors affecting the vertical distribution of the biomass are complex and highly variable. The [Chl a] spatial distribution in the Mediterranean Sea mimics, on smaller scales, what is observed in the global ocean. As already evidenced by analyzing satellite surface observations, midlatitude- and subtropical-like phytoplankton dynamics coexist in the Mediterranean Sea. Moreover, the Mediterranean DCM variability appears to be characterized by patterns already observed on the global scale.

This paper is the outcome of a workshop held in Rome in November 2011 on the occasion of the 25th anniversary of the POEM (Physical Oceanography of the Eastern Mediterranean) program. In the workshop discussions, a number of unresolved issues were identified for the physical and biogeochemical properties of the Mediterranean Sea as a whole, i.e., comprising the Western and Eastern sub-basins. Over the successive two years, the related ideas were discussed among the group of scientists who participated in the workshop and who have contributed to the writing of this paper. Three major topics were identified, each of them being the object of a section divided into a number of different sub-sections, each addressing a specific physical, chemical or biological issue: 1. Assessment of basin-wide physical/biochemical properties, of their variability and interactions. 2. Relative importance of external forcing functions (wind stress, heat/moisture fluxes, forcing through straits) vs. internal variability. 3. Shelf/deep sea interactions and exchanges of physical/biogeochemical properties and how they affect the sub-basin circulation and property distribution. Furthermore, a number of unresolved scientific/methodological issues were also identified and are reported in each sub-section after a short discussion of the present knowledge. They represent the collegial consensus of the scientists contributing to the paper. Naturally, the unresolved issues presented here constitute the choice of the authors and therefore they may not be exhaustive and/or complete. The overall goal is to stimulate a broader interdisciplinary discussion among the scientists of the Mediterranean oceanographic community, leading to enhanced collaborative efforts and exciting future discoveries. © Author(s) 2014.

In questo capitolo ci occupiamo della misura dei parametri che sono utili a caratterizzare lo stato fisico del sistema marino ed a studiare i processi che in questo avvengono. La temperatura e la salinità sono due variabili fondamentali che, assieme alla pressione, permettono di ricostruire attraverso algoritmi matematici altre proprietà fisiche importanti, la densità in primo luogo. Nel seguito presenteremo gli strumenti e i metodi più attuali e/o più in uso per la loro misura o calcolo, sviluppando ed ampliando quanto già descritto nel volume "Metodi nell'ecologia del plancton marino" (Innamorati et al., 1990).

La distribuzione verticale della respirazione del microplancton, determinata quantificando l'attività del sistema di trasporto degli elettroni (ETS), è stata studiata nell'epi-, meso- e batipelago del Mar Tirreno (Mar Mediterraneo). I dati ETS determinati nell'epipelago sono stati calibrati con delle misure al buio di utilizzazione comunitaria dell'ossigeno in vitro [OUR (l O2 h-1 dm-3)=0,661 x ETS - 0,023] ottenute dai medesimi campioni d'acqua. Usando questa relazione per i dati ETS registrati nell'epipelago (0

The annual cycle of plankton was studied over 14 years from 1984 to 2000 at a coastal station in the Gulf of Naples, with the aim of assessing seasonal patterns and interannual trends. Phytoplankton biomass started increasing over the water column in February-early March, and generally achieved peak values in the upper layers in late spring. Another peak was often recorded in autumn. Diatoms and phytoflagellates dominated for the largest part of the year. Ciliates showed their main peaks in phase with phytoplankton and were mainly represented by small (< 30 mm) naked choreotrichs. Mesozooplankton increased in March-April, reaching maximum concentrations in summer. Copepods were always the most abundant group, followed by cladocerans in summer. At the interannual scale, a high variability and a decreasing trend were recorded over the sampling period for autotrophic biomass. Mesozooplankton biomass showed a less marked interannual variability. From 1995 onwards, phytoplankton populations increased in cell number but decreased in cell size, with intense blooms of small diatoms and undetermined coccoid species frequently observed in recent years. In spite of those interannual variations, the different phases of the annual cycle and the occurrence of several plankton species were remarkably regular., El ciclo anual del plancton se estudió a lo largo de 14 años, desde 1984 a 2000, en una estación costera del golfo de Nápoles, con el objetivo de discernir pautas estacionales y tendencias interanuales. La biomasa fitoplanctónica empezaba a aumentar en la columna de agua en febrero-primeros de marzo, y generalmente alcanzaba valores máximos en las capas superiores a finales de primavera. Se solía registrar otro máximo en otoño. Las diatomeas y los fitoflagelados dominaron durante la mayor parte del año. Los ciliados presentaron sus máximos principales en fase con el fitoplancton y estuvieron representados principalmente por pequeños (< 30 ?m) coreotricos desnudos. El mesozooplancton aumentó en marzo-abril, llegando a concentraciones máximas en verano. Los copépodos fueron siempre el grupo más abundante, seguidos de los cladóceros en verano. A la escala interanual, la biomasa autotrófica registró una elevada variabilidad y una tendencia decreciente a lo largo del período de muestreo. La biomasa del mesozooplancton mostró una variabilidad interanual menos marcada. Desde 1995 en adelante, las poblaciones de fitoplancton aumentaron en número de células, pero el tamaño celular se redujo, y en años recientes se han observado floraciones intensas de diatomeas pequeñas y de especies cocoides no determinadas. A pesar de estas variaciones interanuales, las distintas fases del ciclo anual y la presencia de varias especies planctónicas fueron notablemente regulares.

Respiratory electron transport system (ETS) measurements of the microplankton were performed along a south-north transect from themarginal ice zone (MIZ) to the pack ice-covered zone. ETS activity ranged from 0.14 to 1.47 ml O2h-1m-3(mean value ±SD: 0.85 ±0.35ml O2h-1m-3) under the ice and from 0.17 to 2.81ml O2h-1m-3(mean value ±SD: 1.47 ±0.80 ml O2h-1m-3) in the marginal ice zone.The MIZ ecosystem was net autotrophic (P/R>1) while the pack ice zone was net hetertrophic (P/R

During the last 15 years, the knowledge of Mediterranean physical dynamics as well as of atmospheric forcing underwent a tremendous improvement because of the action within several international programs and the development of remote sensing and modelling approaches. Curiously, it is still very difficult to build up a climatological database for chemical and basic biological parameters for the whole basin because most of the data published in the open literature were preferentially related to meso- to small-scale processes. Within the European Union project Mass Transfer and Ecosystem Response (MATER), systematic measurements of routine chemical parameters, such as dissolved oxygen and nutrients, have been conducted. They will fill the existing gap between physical and chemical information. In this paper, we analyze the hydrographic data from a cruise conducted in the fall 1996 in the Central Mediterranean region and report, for the first time, on oxygen and nutrient concentrations, ranges and distributions. The joint analysis of T– S properties and chemical data also allows a better definition of water mass characteristics in this crucial area and hints at basic mechanisms relevant to water mass transformation and biological production in the basin.

The major aim of this paper is the validation of SeaWiFS derived chlorophyll-a concentration in the Mediterranean Sea. A data set containing in situ chlorophyll-a profiles and optical measurements of in water and above water radiances was used to evaluate the performances of several ocean color algorithms in the Mediterranean Sea. The analysis revealed a systematic overestimation of chlorophyll-a concentration by NASA global algorithms (OC2v4 and OC4v4). The error appears to be correlated with chlorophyll-a concentration, by exhibiting marked differences at low values(C < 0.15 mg/m3). In particular at low concentration, the bias observed for OC2v4 is about twice that observed for OC4v4. The same analysis made using the Gitelson et al. (1996) CZCS regional algorithm revealed that this model underestimate the pigments concentration but it does not exhibit a correlation between the error and the measures. On the other hand, when the NASA standard algorithms are applied to remotely sensed data the behavior appears reversed: the OC2v4 algorithm exhibits better estimates than OC4v4, which is probably more affected by atmospheric correction problems. When applied to satellite data, the GIT algorithm performs better than the NASA global algorithms, even though the estimates are very poor in the high chlorophyll-a range. Two new Mediterranean algorithms are then proposed by fitting our Mediterranean bio-optical data set with a linear and an OC2-like functional forms. The new algorithms perform well when applied either to the bio-optical measurements or to satellite data. The different behavior of the same algorithm when applied to bio-optical measurements or to remotely sensed data demonstrates that the atmospheric correction is still the main source of error in ocean color data. Due to the relatively small number of available in situ data, the algorithms that we generated have to be considered very preliminary. Discussion was carried out on the reasons of the global algorithms misfit, providing possible explanations and some preliminary result. The influence of coccolithophores and of the yellow substance on the optical response of the Mediterranean waters is investigated, showing that they can at least partially explain the systematic misfit. All the above show that a region like the Mediterranean Sea requires an independent treatment of the atmospheric and the in water bio-optical term to obtain reliable estimates of phytoplankton activity.