Assessment of spatial environmental quality status in Ria de Aveiro (Portugal)

Abstract

SUMMARY: The productivity of Ria de Aveiro is sustained by the large quantities of dissolved inorganic nutrients, mainly from freshwater inputs (e.g. agricultural drainage) and organic-rich anthropogenic point sources (e.g. urban sewage). The concentration of silicate and nitrate showed a similar seasonal variation and conservative behaviour, since 63 to 96% of the total variance of the concentration of silicate and 88 to 96% of the total variance of the concentration of nitrate were explained by salinity. On the other hand, the concentration of nitrite, ammonium, and phosphate did not seem dependent on the freshwater inputs, showing a random distribution with salinity. Nutrient concentrations were always higher in the two inner areas than at the outer boundary of the system. Chlorophyll a showed higher concentrations throughout spring and summer, and also in the inner areas. The annual variation of N:P, N:Si and phytoplankton biomass suggests that there is a large excess of nitrate. The results suggest that within a system with low overall eutrophic condition (OEC) and low susceptibility (US-NEEA index), the quality status of different areas within the system can vary (Applying the EU-WFD criteria proposed for the trophic classification of the Baltic Sea). This work also suggests that in coastal lagoons such as Ria de Aveiro, where the quality status of certain specific areas may vary, these particular areas should be taken under consideration for specific monitoring programmes and management measurements, particularly with regard to anthropogenic point sources.Keywords: eutrophication, chlorophyll a, nitrogen, phosphorous, silicate, estuaries. RESUMEN: EVALUACIÓN DE LA CALIDAD AMBIENTAL EN LA RÍA DE AVEIRO (PORTUGAL). -La productividad de la Ría de Aveiro está sostenida por grandes cantidades de nutrientes inorgánicos disueltos, procedentes principalmente de aportes de aguas dulces (e.g. de la drenaje agrícola) y por puntos de ricos aportes orgánicos de origen antropogénico (e.g. aguas residuales urbanas). La concentración de silicatos y nitratos mostraron variaciones estacionales similares un comportamiento conservativo, en el que la salinidad explicó del 63 al 96% de la varianza total de la concentración de silicato y un 88 al 96% de la varianza total de la concentración nitratos. Al contrario, la concentración de nitrito, amonio, y fosfato no pareció depender de los aportes de agua dulce, mostrando una distribución al azar con la salinidad. Las concentraciones de nutrientes fueron siempre más altas en las dos áreas más internas, cuando se compararon con el límite exterior del sistema. La clorofila a presentó mayores concentraciones a lo largo de la primavera y verano, y fue siempre más alta en las áreas interiores. La variación anual de N:P, N:Si y biomasa de fitoplancton sugieren que hay un gran exceso de nitratos. Los resultados sugieren que dentro de un sistema con una condición eutrófica general baja (OEC) y un bajo índice de susceptibilidad (US-NEEA), el estatus de calidad de las diferentes áreas dentr...

Seasonal patterns of bacterioplankton composition in a semi-intensive European seabass (Dicentrarchus labrax) aquaculture system

“…Temperature, pH and TOC were highest in July and September while nitrite and nitrate concentrations were highest in January and March (Figure 1A). A similar seasonal variation in nitrate concentration has been previously reported in the Ria de Aveiro estuary, with concentrations reaching the highest values in winter due to high nitrate-rich river waters inputs (Lopes et al, 2007). The months sampled, suggesting that a lower sequencing effort could be used to characterize this compartment when compared with estuarine water.…”

Physiological responses of the European cockle Cerastoderma edule (Bivalvia: Cardidae) as indicators of coastal lagoon pollution

“…In the present study, the local food supply was not verified. However, according to measurements by Lopes et al (2007) of chlorophyll-a, dissolved nitrogen and phosphate concentrations, Ria de Aveiro has moderately low overall eutrophic conditions. The inner stations (e.g., Cais do Bico do Laranjo and Ílhavo) are considered eutrophic, and the outer stations (e.g., Barra) are classified as mesotrophic.…”

Are the impacts of carbon nanotubes enhanced in Mytilus galloprovincialis submitted to air exposure?

“…Estuaries are dynamic interface zones between water draining from inland river basis and oceans, and for this reason normally receive high concentrations of natural and anthropogenic materials (Amiard-Triquet andRainbow, 2009, Müller et al, 1995;Lopes et al, 2011). Pollutants from different anthropogenic sources are increasing in marine ecosystems which can cause adverse effects (Fu et al, 2003;Maanan, 2008).…”