The seasonal dynamics of nutrient and chlorophyll a concentrations on the SE Mediterranean shelf-slope

We report the results of a sequence of twelve research cruises over a two-year period, from June 1996 through May 1998 that examined the seasonal variations in the nutrient (NO(3)(-) PO(4)(3-), and Si(OH)(4)) and in the chlorophyll a (Chl a) concentrations at two permanent stations across the SE Mediterranean continental shelf and slope (120 and 400 m water depth off the Israeli coast). Seasonally-dependent Chl a concentrations ranged between 0.003 and 0.415 mg m(-3). Following autumn and winter a distinct biomass phytoplankton peak was produced (similar to 30 mg Chl a m(-2) in the upper 120 m) and a subsequent moderate spring peak was observed. In the decomposition zone (120-400 m), an opposite pattern was observed with decreasing amounts of NO(3)(-) and PO(4)(3-) during winter. The integrated Si(OH)(4) pattern in the euphotic zone indicates that diatoms grow during spring and summer and that their frustules are rapidly settled during the breakdown of stratification. At depths between 150 and 400 m, the geometric mean NO(3)(-)/PO(4)(3-) ratio (similar to 24) was significantly higher than in the upper 150 m (similar to 7), where it varied seasonally with low ratios (3, 5) during autumn and winter compared to summer and spring (9, 11). At the present time, it is not possible to reconcile the relatively low ( 20) ratios of exogenous upwelling and atmospheric inputs. The determination of the possible presence of additional nutrient phases and preferential uptake of nutrients by the phytoplankton is an important next step toward the understanding of nutrient limitation in such ultra-oligotrophic systems. (Ce travail présente les résultats d'une série de douze campagnes (juin 1996 à mai 1998) portant sur les nutriments (nitrates, phosphates et silicates) et la chlorophylle a. L’étude a porté sur deux stations permanentes, l'une sur la plate-forme (profondeur 120 m), l'autre sur la pente continentale (400 m) au SE de la Méditerranée. Les variations de la chlorophylle a s’étendent de 0,003 à 0,415 mg m–3. Un pic de chlorophylle apparaı̂t aussi bien en fin d'automne qu'en fin d'hiver (≠ 30 mg Chl a m–2 dans les 120 premiers mètres) avec un maximum secondaire à la fin du printemps. Dans la zone de décomposition (120 m à 400 m), les variations de nitrates et de phosphates présentent une allure opposée avec une diminution durant l'hiver. Le modèle intégré de Si(OH)4 dans la couche euphotique souligne la rupture de la stratification verticale. Entre 150 m et 400 m, la moyenne géométrique du rapport NO3–/PO43– (≠ 24) est nettement plus élevée que dans les cent cinquante premiers mètres (≠ 7) où il varie avec les saisons avec des valeurs basses (respectivement 3 et 5) en automne – hiver comparé à l’été et au printemps (respectivement 9 et 11). Actuellement, il est impossible de relier les rapports nitrates/phosphates relativement bas ( 20) des apports atmosphériques et de l'upwelling extérieur. L'apport additionnel de nutriments, ainsi que les préférences éventuelles du phytoplancton, constituent la prochaine étape pour la compréhension de la limitation par les nutriments dans les systèmes ultra-oligotrophes

PERSEUS ODV QC software

The PERSEUS ODV QC Utility has been developed in the framework of the PERSEUS project.[1] The QC Utility implements a QC procedure for ODV files and assigns QC flags to metadata and data values according to the SEADATANET vocabulary L20. The QC procedure results are QC flags in an ODV file and a log file with a list of possible errors. The QC Utility can operate both in the window and console modes. The QC procedure includes a set of metadata and data quality tests. The metadata tests are: location check, date/time (including velocity and chronology) check and sea depth check. The data tests are based on check arrays (climate, statistics, parameter ranges and thresholds for spikes and gradients check) for sub-regions (local) or the entire region (regional). These arrays are assigned to the P02 parameter codes. The P01 codes are not used because of their superfluity (many codes correspond to the same parameter). The P02 vocabulary is more suitable but it does not provide identification of all parameters. The QC Utility gives a possibility of extending the P02 codes list to identify the parameters more correctly. Data tests include sounding value check (including order check), climatic check (if climatic arrays for the parameter are available), statistic check (if statistic arrays for the parameter are available), range check (if ranges for the parameter are available), fixing density inversions for hydrological data, fixing spikes (if corresponding thresholds for the parameter are available), gradient check (if corresponding thresholds for the parameter are available)

PERSEUS QC: Preparing statistic data sets

Proceedings of SPIE - The International Society for Optical Engineering, 2017, Volume 10444, Article number 104440IThe Desktop Oceanographic Data Processing Module was developed for visual analysis of interdisciplinary cruise measurements. The program provides the possibility of data selection based on different criteria, map plotting, sea horizontal sections, and sea depth vertical profiles. The data selection in the area of interest can be specified according to a set of different physical and chemical parameters complimented by additional parameters, such as the cruise number, ship name, and time period. The visual analysis of a set of vertical profiles in the selected area allows to determine the quality of the data, their location and the time of the in-situ measurements and to exclude any questionable data from the statistical analysis. For each selected set of profiles, the average vertical profile, the minimal and maximal values of the parameter under examination and the root mean square (r.m.s.) are estimated. These estimates are compared with the parameter ranges, set for each sub-region by MEDAR/MEDATLAS-II and SeaDataNet2 projects. In the framework of the PERSEUS project, certain parameters which lacked a range were calculated from scratch, while some of the previously used ranges were re-defined using more comprehensive data sets based on SeaDataNet2, SESAME and PERSEUS projects. In some cases we have used additional sub- regions to redefine the ranges ore precisely. The recalculated ranges are used to improve the PERSEUS Data Quality Control

Influence of cyclonic and anticyclonic eddies on plankton in the southeastern Mediterranean Sea during late summertime

International audiencePlanktonic food webs were studied contemporaneously in a mesoscale cyclonic (upwelling, ∼ 13 months old) and an anticyclonic (downwelling, ∼ 2 months old) eddy as well as in an uninfluenced background situation in the oligotrophic southeastern Mediterranean Sea (SEMS) during late summer 2018. We show that integrated nutrient concentrations were higher in the cyclone compared to the anticyclone or the background stations by 2-13-fold. Concurrently, Synechococcus and Prochlorococcus were the dominant autotrophs abundance-wise in the oligotrophic anticyclone (∼ 300 × 1010 cells m-2). In the cyclone, functional groups such as dinoflagellates, Prymnesiophyceae and Ochrophyta contributed substantially to the total phytoplankton abundance (∼ 14 × 1010 cells m-2), which was ∼ 65 % lower at the anticyclone and background stations (∼ 5 × 1010 cells m-2). Primary production was highest in the cyclonic eddy (191 mgCm-2d-1) and 2-5-fold lower outside the eddy area. Heterotrophic prokaryotic cell-specific activity was highest in the cyclone (∼ 10 fgCcell-1d-1), while the least productive cells were found in the anticyclone (4 fgCcell-1d-1). Total zooplankton biomass in the upper 300 m was 10-fold higher in the cyclone compared with the anticyclone or background stations (1337 vs. 112-133 mg C m-2, respectively). Copepod diversity was much higher in the cyclone (44 species), compared to the anticyclone (6 small-size species). Our results highlight that cyclonic and anticyclonic eddies show significantly different community structure and food-web dynamics in oligotrophic environments, with cyclones representing productive oases in the marine desert of the SEMS

Operational evaluation of the Mediterranean Monitoring and Forecasting Centre products: Implementation and Results

A web-based validation platform has been developed at the Istituto Nazionale di Geofisica e Vulcanologia (INGV) for the Near Real Time validation of the MyOcean-Mediterranean Monitoring and Forecasting Centre products (Med-MFC). A network for the collection of the in-situ observations, the nested sub-basin forecasting systems model data (provided by the partners of the Mediterranean Operational Oceanography Network, MOON) and the Sea Surface Temperature (SST) satellite data has been developed and is updated every day with the new available data. The network collects temperature, salinity, currents and sea level data. The validation of the biogeochemical forecast products is done by use of ocean colour satellite data produced for the Mediterranean Sea. All the data are organized in an ad hoc database interfaced with a dedicated software which allows interactive visualizations and statistics (CalVal SW). This tool allows to evaluate NRT products by comparison with independent observations for the first time. The heterogeneous distribution and the scarcity of moored observations reflect with large areas uncovered with measurements. Nevertheless, the evaluation of the forecast at the locations of observations could be very useful to discover sub-regions where the model performances can be improved, thus yielding an important complement to the basin-mean statistics regularly calculated for the Mediterranean MFC products using semi-independent observations

MeDir-OP, a Mediterranean directory for operational oceanography developed within the MAMA Project

The Mediterranean network to Assess and upgrade the Monitoring and forecasting Activity (MAMA), a 3-year thematic network project shared by leading marine research institutions from all the Mediterranean countries, has contributed to strengthening the institutional and scientific platform for the establishment of operational oceanography in the region. A key task in the MAMA project consisted in the stocktaking of activities and identifi- cation of current capabilities in operational oceanography on a country basis with a focus on availability of technological infrastructures, human resources and funding, applica- tions and product needs. The information was collected by: 1. Country Profiles on the operations of institutes/agencies/organisations dealing with marine monitoring; national structures supporting such activities and marine affairs in general; relevance of marine sectors in the economic activities of each country 2. a structured questionnaire targeting a comprehensive inventory on the routine marine monitoring activities in the Mediterranean. The Mediterranean Directory on Operational Oceanography (MeDir-OP) presents this information through the use of a user-friendly internet-based graphical interface allowing easy viewing of the metadata according to a number of categories. Specific information sets are collated into searchable mini-databases. MeDir-OP provides the basis for assessing the needs and potentials for operational oceanography in the region. It serves as an essential step to identifying gaps in infrastruc- tures, to underpin further research and technological developments specific to the region, and to designing an observing system that meets the needs of end-users.peer-reviewe

Challenges for Sustained Observing and Forecasting Systems in the Mediterranean Sea

The Mediterranean community represented in this paper is the result of more than 30 years of EU and nationally funded coordination, which has led to key contributions in science concepts and operational initiatives. Together with the establishment of operational services, the community has coordinated with universities, research centers, research infrastructures and private companies to implement advanced multi-platform and integrated observing and forecasting systems that facilitate the advancement of operational services, scientific achievements and mission-oriented innovation. Thus, the community can respond to societal challenges and stakeholders needs, developing a variety of fit-for-purpose services such as the Copernicus Marine Service. The combination of state-of-the-art observations and forecasting provides new opportunities for downstream services in response to the needs of the heavily populated Mediterranean coastal areas and to climate change. The challenge over the next decade is to sustain ocean observations within the research community, to monitor the variability at small scales, e.g., the mesoscale/submesoscale, to resolve the sub-basin/seasonal and inter-annual variability in the circulation, and thus establish the decadal variability, understand and correct the model-associated biases and to enhance model-data integration and ensemble forecasting for uncertainty estimation. Better knowledge and understanding of the level of Mediterranean variability will enable a subsequent evaluation of the impacts and mitigation of the effect of human activities and climate change on the biodiversity and the ecosystem, which will support environmental assessments and decisions. Further challenges include extending the science-based added-value products into societal relevant downstream services and engaging with communities to build initiatives that will contribute to the 2030 Agenda and more specifically to SDG14 and the UN's Decade of Ocean Science for sustainable development, by this contributing to bridge the science-policy gap. The Mediterranean observing and forecasting capacity was built on the basis of community best practices in monitoring and modeling, and can serve as a basis for the development of an integrated global ocean observing system