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European Marine Observation and Data Network (EMODnet)

An integrative tool for the assessment of eutrophication status at the sub-basin level in the Mediterranean region

The user organisation

The European Commission Directorate-General for Environment (EC DG ENV) has funded research in the Mediterranean Member States as part of the MEDREGION project to support the implementation of Good Environmental Status (GES) as defined under the Marine Strategy Framework Directive (MSFD). 

Various research institutes and monitoring organisations from Italy, Croatia, Slovenia and Greece carried out studies to contribute to this purpose focusing on descriptor 5: “Human-induced eutrophication is minimised, especially adverse effects thereof, such as losses in biodiversity, ecosystem degradation, harmful algae blooms and oxygen deficiency in bottom waters”. The organisations involved were: the National Institute of Oceanography and Applied Geophysics - OGS (Italy), the Hellenic Centre for Marine Research – HCMR (Greece), the Marine Research, Basque Research and Technology Alliance - BRTA (Spain), the National Institute of Biology - NIB (Slovenia), the Italian Institute for Environmental Protection and Research - ISPRA (Italy), the Institute of Oceanography and Fisheries - IOF (Croatia).

Challenges faced by the user

Researchers developed a common methodology for the determination of eutrophication thresholds and reference values for the Eastern Mediterranean Sea basin. They also tested an integrative tool as a common assessment method for eutrophication status. In particular, threshold values were set for the parameters: dissolved inorganic nitrogen (DIN), phosphate, total phosphorus (TP), Chlorophyll-a, transparency and dissolved oxygen in the bottom waters of the Adriatic and Levantine – Aegean sub-regions. To better understand the relevance of this study, the definition of the terms “criteria” and “threshold values” according to the MSFD is given below. Criteria are laid down in the Commission Decision (EU) 2017/848 establishing criteria and methodological standards for GES of marine waters and specifications and standardised methods for monitoring and assessment. According to the decision, some criteria for Descriptor 5 (Eutrophication) require that specific criteria elements, i.e. water transparency, nutrients, chlorophyll and oxygen concentrations, are not at a level that indicates adverse effects of nutrient enrichment. Threshold values are set in relation to a reference condition, a state with no or minimal impact from anthropogenic activities, and may include an "acceptable deviation" that allows sustainable use of the marine environment. 

The study was the first attempt to establish common methodologies and methodological standards for the assessment of eutrophication status at the sub-basin level in the Mediterranean Sea, which is essential in marine environments shared by many countries. In particular, the aggregated, harmonised and validated datasets accessible through EMODnet Chemistry allow researchers to establish reference conditions and target values. The latter primarily define the level above which a reduction of individual anthropogenic pressures is required to achieve GES.

EMODnet services used

The researchers of the organisations listed and participating in the project, used the data included in the Mediterranean Sea - Eutrophication and Acidity aggregated datasets released by EMODnet Chemistry in 2021. EMODnet Chemistry regularly releases aggregated, standardised, and validated data, which are made available as regional and global data collections on eutrophication, ocean acidification, contaminants, and marine litter on the EMODnet Portal. In this study only stations with a minimum of four samplings per year distributed in four seasons (Jan-Feb-Mar; Apr-May-Jun; Jul-Aug-Sep; Oct-Nov-Dec) were considered and at least one sampling in each season was considered necessary for each station. Only stations for which temperature, salinity, chlorophyll, dissolved oxygen in bottom waters and nutrients were simultaneously available, were selected. In total, 70 stations were used in the Adriatic Sea and 11 stations in the Saronikos Gulf (Levantine-Aegean marine region), totalizing 81 stations. 

Impact of EMODnet

The availability of sufficient spatial and temporal coverage of the data is crucial for testing statistical approaches. Also crucial is the reliability, interoperability and reusability of the data, which EMODnet Chemistry ensures thanks to its standardisation and quality control procedures and its extensive metadata.

Standardised, harmonised and validated data available through EMODnet Chemistry represent a fundamental resource to enable the definition of reference conditions and threshold values that are urgently needed for the assessment of the state of the environment according to EU policy requirements. This work shows the advantage of using data on the EMODnet Portal. They are managed according to common standard procedures to also allow analyses on a sub-regional level (e.g. Eastern Mediterranean). - Marina Lipizer (OGS)

Reference

Refs: Giani, M., Pavlidou, A., Kralj, M., Varkitzi, I., Borja, A., Menchaca, I., ... & Pagou, K. (2024). Assessment of the eutrophication status at Mediterranean sub-basin scale, within the European Marine Strategy Framework Directive. Science of the total environment, 945, 173876. https://doi.org/10.1016/j.scitotenv.2024.173876 

Figure: Graphical abstract of the study (Figure included in the scientific paper: https://doi.org/10.1016/j.scitotenv.2024.173876 )


Figure: Geographical areas covered by the research: Adriatic Sea (Italy, left map) and Saronikos Gulf (Greece, right map) within the Eastern Mediterranean (Figure included in the scientific paper: https://doi.org/10.1016/j.scitotenv.2024.173876 )


Figure: Eutrophication assessment values for each Spatial Assessment Unit (SAU) resulting from research: “High” in blue; “Good” in green; “Moderate” in yellow for the Adriatic coastal waters (upper table) and the Saronikos Gulf (lower table) (Figure included in the scientific paper: https://doi.org/10.1016/j.scitotenv.2024.173876 )