Opening the black box of coastal inshore waters in the nw mediterranean sea: environmental quality tools and assessment
- Autores: Eva Flo
- Directores de la Tesis: Jordi Camp Sancho (dir. tes.), José Antonio Jiménez Quintana (tut. tes.)
- Lectura: En la Universitat Politècnica de Catalunya (UPC) ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Antoni Munné Torras (presid.), Juan Pablo Sierra Pedrico (secret.), María Fuensanta Salas Herrero (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencias del Mar por la Universidad de Barcelona y la Universidad Politécnica de Catalunya
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Coastal inshore waters (CIW) are defined as the area of coastal waters between 0 and 200 m from the shoreline. They only represent < 1% of coastal waters, even though they are of main ecological, social, and economic importance. However, studies related to CIW are scarce and, thus, they are very poorly known and understood. The time series data base of the National Catalan Coastal Water Monitoring Program, conducted since 1990, has allowed characterizing the CIW in the NW Mediterranean Sea.
CIW receive a larger influence of continental nutrient-rich freshwater inflows than outermost coastal waters. These influences trigger the primary production (chlorophyll-a concentration), which can enhance the eutrophication process. In addition, they are fluvial or urban. The fluvial continental influences are related to natural processes, such as fluvial inflows and submarine groundwater discharges, and are defined by a high freshwater content (inverse of salinity) and a high nitrate, and silicate concentrations. The urban ones are mainly related to urban inflows, thus of anthropogenic origin, and are defined by high phosphate, ammonia, and nitrite concentrations.
During the study period (1990-2014), physicochemical and biological data analyses revealed great differences between CIW and outermost coastal waters, in space and time and at national and local scales. CIW showed significantly larger concentrations of dissolved inorganic nutrients and chlorophyll-a than outermost coastal waters. Within CIW, Fluvial continental influences occurred predominantly in coastal zones where rivers flow into, such as in the southwest where the Ebre river discharges, and urban continental influences occurred along the metropolitan Barcelona area and near mostly urban areas. Besides, fluvial continental influences decreased while urban continental influences increased with time. In addition, CIW showed higher variability and heterogeneity, especially at local scale.
These evidences had allowed the creation of methods to assess pressures (nutrients) on land and on coastal waters and also the impact they drive (chlorophyll-a) on coastal waters, as required by the Water Framework Directive. The land uses simplified index (LUSI) method assesses the continental pressures measured on land and its influence on coastal waters, based on land uses and coastline morphology. The Phosphate-Ammonium-Nitrite (FAN) and FLUviality (FLU) indexes method, which is based on physicochemical variables, assesses the continental influences, the urban and fluvial ones, the water quality, and the anthropogenic component of the trophic state and the risks of eutrophication and cultural eutrophication on coastal waters. The chlorophyll-a method, which is based on chlorophyll-a concentration (phytoplanktonic biomass) and on salinity, assesses the ecological status of coastal waters and allows to assess the eutrophication on coastal waters. Merging the results of the FAN and FLU indexes and of the Chl-a methods allows to assess the cultural eutrophication on coastal waters.
The integrated assessment of the Catalan coast, based on the jointly results of the created methods, revealed that the 42% of the water bodies are at risk of eutrophication, 19% are at risk of cultural eutrophication, 8% show eutrophication, and 2% show cultural eutrophication. Therefore, the assumption regarding the oligotrophy of the Mediterranean Sea is rejected in CIW of the Catalan Coast.
The combined evidences of the characterization and assessments of the Catalan coastal waters provide a better understanding of the structure and functioning of coastal waters, especially of CIW, in the Mediterranean Sea, which is essential for decision-makers. In addition, scientific recommendations were provided to achieve in the future the integrated management of the Catalan coast, under the ecosystem approach.
