Analysis of the effects of wet and dry seasons on a Mediterranean river basin: consequences for coastal waters and its quality management

Rivers play a major role in the delivery of nutrients to coastal ecosystems which are essential for ecosystem productivity. However, the increase of nutrients due to anthropogenic activities can cause eutrophication problems. This study analyzes the seasonal variation of phytoplankton communities in the coastal receiving waters of a Mediterranean river. Two scenarios are compared: the wet and the dry season with distinctive characteristics. During the wet season agricultural runoff and combined sewer overflows (CSO) were responsible for nutrient discharges, while during the dry season partially treated effluent from wastewater was the main nutrient source. In the receiving waters, diatoms typical seasonal cycle was modified by CSO discharges during rain episodes, while dinoflagellate abundance was higher in the dry season due to partially treated effluents discharges and low turbulence. We recommend that the design of the Water Framework Directive monitoring programs should take into account wastewater treatment plants and combined sewer systems located near the coast. Management decisions should take into account that only reductions in CSO and partially treated summer effluent are likely to be efficient in the short term. Analyzing the corrective measures cost through a cost-benefit analysis would help to determine whether the costs are excessive or not.Sebastiá Frasquet, MT.; Rodilla Alamá, M.; Falco Giaccaglia, SL.; Sanchís Blay, JA. (2013). Analysis of the effects of wet and dry seasons on a Mediterranean river basin: consequences for coastal waters and its quality management. Ocean and Coastal Management. 78(3):45-55. doi:10.1016/j.ocecoaman.2013.03.012S455578

Estimation of chlorophyll «A» on the Mediterranean coast using a QuickBird image

Remote sensing has proved a useful tool for monitoring and assessing water quality. However, little research has been conducted using satellite images with high spatial resolution to analyze coastal areas with high variability near shore. The objective of this research was to develop a model for estimating chlorophyll-a concentration on the Gandia coast (Western Mediterranean) by means of a high resolution QuickBird image. Several linear regressions were calculated to find the best chlorophyll-a model. The optimal model was found when blue and red bands were used. The retrieval accuracy (R2 ) was 0.92, while the root mean square (RMSE) was 0.34 mg/m3 . The selected model was validated with an independent data set and the estimation of chlorophyll-a was reasonably accurate (R2= 0.90). The results obtained in this study suggest that using a QuickBird sensor is an effective technique for monitoring the ecological status of coastal areas with an inherent high variability.La teledetección ha demostrado ser una herramienta útil para el monitoreo y la evaluación de la calidad del agua. Sin embargo, pocas investigaciones se han llevado a cabo utilizando imágenes de satélite con alta resolución espacial para analizar las zonas costeras con alta variabilidad cerca de la costa. El objetivo de esta investigación fue desarrollar un modelo para estimar la concentración de clorofila-a en la costa de Gandia (Mediterráneo occidental) por medio de una imagen de alta resolución QuickBird. Varias regresiones lineales se calcularon para encontrar el mejor modelo de clorofila- a. El modelo óptimo se obtuvo cuando se utilizaron las bandas 1 (azul) y 3 (rojo) con un valor del coeficiente de determinación (R2) de 0,92, mientras que el error medio cuadrático (RMSE) fue de 0,34 mg/m3. Se validó el modelo seleccionado mediante un conjunto de datos independientes obteniendo un valor de R2 de 0,90. Los resultados obtenidos en este estudio sugieren que el uso del sensor Quick-Bird puede ser una técnica eficaz para el seguimiento del estado ecológico de las zonas costeras con una alta variabilidad inherente.Sebastiá Frasquet, MT.; Estornell Cremades, J.; Rodilla Alamá, M.; Marti Gavila, J.; Falco Giaccaglia, SL. (2012). Estimation of chlorophyll «A» on the Mediterranean coast using a QuickBird image. Revista de Teledetección. (37):23-33. http://hdl.handle.net/10251/36141S23333

Influence of nutrient inputs from a wetland dominated by agriculture on the phytoplankton community in a shallow harbour at the Spanish Mediterranean coast

[EN] The Safor Wetland (Western Mediterranean) is a protected ecosystem declared Site of Community Importance under the Habitats Directive. Agricultural practices have been part of this ecosystem throughout history, and its hydrology is anthropogenically manipulated to satisfy cultivation needs. Freshwater from the wetland is discharged through surface channels to Gandia Harbour, a shallow water body with high water residence time. This study evaluated the linear eutrophication gradient downstream from the freshwater inflow locations. The role of the main nutrients in determining the phytoplankton community is discussed. The predominance of agricultural practices, 48% of the watershed soil, caused an excess of nitrogen and an imbalance in the nutrient ratios at all the sampling points. Phosphorus concentrations were particularly low, and did not exceed 1.0 ¿M. Chlorophyll-a concentration was of the order of that found in other eutrophic estuarine waters. In general, flagellates dominated over diatoms at all the harbour sampling points and depths. Potentially blooming species of both phytoplankton groups were detected. The correct implementation of the existing agricultural best management practices should continue to reduce nitrogen and phosphorus loading to the estuary. It seems reasonable that for effective control of the eutrophication effects in this area, strict control over wastewater point sources should be also exercised. © 2012 Elsevier B.V.Sebastiá Frasquet, MT.; Rodilla Alamá, M.; Sanchís Blay, JA.; Altur Grau, VJ.; Gadea Pérez, MI.; Falco Giaccaglia, SL. (2012). Influence of nutrient inputs from a wetland dominated by agriculture on the phytoplankton community in a shallow harbour at the Spanish Mediterranean coast. AGRICULTURE ECOSYSTEMS & ENVIRONMENT. 152(3):10-20. doi:10.1016/j.agee.2012.02.006S1020152

Spatial and temporal patterns of water quality in Cullera Bay

[EN] The Júcar River, characterized by a very irregular freshwater flow, discharges into the Spanish Mediterranean coastal waters. However, the flow at its mouth is usually insignificant due to the overexploitation of upstream water. Under normal conditions, the final stretch of the river (downstream from the Cullera weir) is nurtured only by water released from the weir and small discharges from lateral irrigation channels. During periods of heavy rain, however, a significant amount of water flows through the Cullera weir. An analysis of data acquired during several field campaigns in Cullera Bay clearly reveals a zonal distribution of nutrients and chlorophyll-a within the bay: a southern area of continental influence, located near the mouth of the Júcar River; a region affected by karst filtrations and minor freshwater inputs, located to the north of the bay around Cullera Cape; and a third zone in between, characterized by higher salinities. Spatial salinity distribution is indicative of the spatial distribution of some of the nutrients discharged by the river, particularly nitrite, nitrate, orthosilicic acid and total phosphorus (TP), since it has been shown that their behavior is inverse to that of salinity. However, neither soluble reactive phosphorus (SRP) nor ammonium, which are mainly affected by biological activity, show this type of behavior. Five different conditions/scenarios were identified during the overall sampling period based on the time-series analysis of wind parameters, rainfall, freshwater flow, salt-wedge thickness at the measuring station on the river, and by comparing the average surface salinity at the sea stations with the values obtained at the coastal stations.This study was financed by the European Union as a part of the ECOSUD project ("Estuaries and Coastal Areas. Basis and Tools for a More Sustainable Development". Reference no. ICA4-CT-2001-10027), AQUAS project ("Water quality and sustainable aquaculture. Links and implications". Reference no. INCO-CT-2005-015105) and by a Special Action by the Spanish Science and Technology Ministry, "Bases y herramientas para el desarrollo sostenible de zonas costeras y estuarinas" (Reference no. REN2001-5510-E).Falco Giaccaglia, SL.; Hermosilla Gómez, Z.; Romero Gil, I.; Martínez Guijarro, MR.; Sierra, J.; Mösso, C.; Mestres, M. (2007). Spatial and temporal patterns of water quality in Cullera Bay. Journal of Coastal Research. SI47:40-47. https://doi.org/10.2112/1551-5036-47.sp1.40S4047SI4

Salinity, nutrient and chlorophyll a vertical variations in the Ebro River plume

Four water sampling campaigns in the Ebro River Plume were carried out, in spring, summer and autumn of 1999 and winter of 2000. In these campaigns salinity, nutrient and chlorophyll spatial distributions in the water column of river plume area were studied (where salinity values increase with depth). The sampling within the first meter of water column was carried out with a specifically designed device (SWAS). This device was designed by Dr. Jean Jacques Naudin to sample in the Rhone River Plume, although some modifications were introduced in the equipment to adapt it to Ebro River Plume conditions in order to obtain a very high vertical resolution in the sampling of the upper water column. Water samples could be acquired simultaneously at eight different depths (0.00, 0.05, 0.10, 0.20, 0.30, 0.50, 0.75 and 1.00 m) plus another additional at 5.0 meters. Salinity, concentration of ammonium, nitrite, nitrate, reactive soluble phosphorus (RSP), total dissolved phosphorus (TDP), total phosphorus (TP), ortosilicic acid and chlorophyll were measured in each water sample. The results of sample analysis allowed to obtain salinity profiles of this surface layer, clearly showing the reduced thickness of river plume when the sea is under low energetic conditions, with a sharp rise of salinity in the first centimeters of water column. Some discontinuities in this pattern were identified, specially when wind blew from the sea, introducing waters of higher salinity and temperature in the upper part of the water column. In most of the sampling stations, nutrient profiles showed a generally decreasing trend of their concentrations with the water depth, although several deviations of this pattern could be observed. These deviations were not due to freshwater load variations and many of them took place in the first 20 centimeters of water column. Since these variations in nutrient concentrations are not apparently related to freshwater loads and/or chlorophyll level changes, the origin of these variations could be planktonic organisms motions in this thin layer and activity changes due to these movements.Romero Gil, I.; Falco Giaccaglia, SL.; Rodilla Alamá, M.; Sierra, J.; González Del Rio Rams, J.; Mösso, C. (2006). Salinity, nutrient and chlorophyll a vertical variations in the Ebro River plume. Journal of Coastal Research. SI39:1828-1832. http://hdl.handle.net/10251/36178S18281832SI3

El programa de vigilancia ambiental de piscifactorias en jaulas flotantes

Se ha analizado el programa de vigilancia ambiental (PVA) de cuatro piscifactorías marinas situadas en el Mediterráneo occidental con el fin de evaluar su grado de idoneidad para detectar posibles impactos en el medio marino. Se ha revisado un elevado número de variables y parámetros físicos, químicos y biológicos en aguas y sedimentos, así como su frecuencia de muestreo. Este trabajo concluye que la calidad del agua no puede ser considerada como un indicador consistente de los impactos, y que resulta mucho más representativo estudiar variables relacionadas con los sedimentos, en especial las relacionadas con el bentos marino. Finalmente, se hace una propuesta de muestreo para los PVA en piscifactorías marinas.The Environmental Monitoring Programme for four fish farms located in the western Mediterranean Sea was studied in order to assess their suitability for detecting possible environmental impact in the surrounding marine ecosystems. A significant number of physical, chemical, and biological parameters, both in water and sediments, were reviewed, as well as their monitoring frequency. These results lead to the conclusion that water quality should not be considered a strong indicator of caged fish farms impact; it is much more appropriate to use other parameters related to sediments, particularly those indicating the health of benthos ecosystems. An Environmental Monitoring Programme for cage fish farms is proposed.Martí Martínez, E.; Martí Insa, CM.; Martínez Guijarro, MR.; Paches Giner, MAV.; Falco Giaccaglia, SL. (2005). El programa de vigilancia ambiental de piscifactorias en jaulas flotantes. Boletin- Instituto Espanol de Oceanografia. 21(21):67-73. http://hdl.handle.net/10251/36174S6773212

Eutrophication of sediments in the Cullera bay: composition and abundance of macrobenthos

Nutrient retention in estuaries and semi-enclosed bays is a principal contributing factor to the relatively high production of these marine systems. Cullera bay occasionally presents serious environmental problems owing to discharge of the Jucar freshwater, sewage from a marine outfall and nutrients release of the sediment. This study examine the macrobenthos in order to evaluate their composition and abundance in anthropogenically impacted coastal sediments and waters. A total of five field campaigns were carried out during years 2002-2003, but, in this paper, we shown the results of the first campaign. The macrobenthos was collected at twelve stations along three transects using a type of Peterson grab, but only we have used the bivalve molluscs because they represent most benthic biomass. To evaluate the influence of environmental factors on the bivalves, we took undisturbed sediment and bottom-water samples at fourteen stations. In water samples we have studied salinity, nutrients, chlorophyll a and suspended solids, and granulometry, organic matter, total nitrogen and total phosphorous in sediment samples. In general exists a high organic matter accumulated in sediments of the bay that increases with depth. The concentration of nutrients of the waters are low, however, the concentration of chlorophyll a suggests a eutrophic character of the shallowest zones. Although bivalve density do not show a clear pattern with every parameters measured, we find some relationships between most abundant bivalves (Donax spp. and Spisula subtruncata) and depth, chlorophyll a of waters and granulometry and nutrients of sediments.Rodilla Alama, M.; Martí Martínez, E.; Falco Giaccaglia, SL.; González Del Rio Rams, J.; Sierra, J.; Sánchez-Arcilla, A. (2006). Eutrophication of sediments in the Cullera bay: composition and abundance of macrobenthos. Journal of Coastal Research. SI 39:1843-1847. http://hdl.handle.net/10251/3617718431847SI 3

Bacteriological quality of the seawater in Cullera Bay, Spain

Localizada en el Mediterráneo español, la Bahía de Cullera está influenciada por las descargas del Río Júcar y por un emisor submarino que descarga sus aguas residuales justo en la desembocadura del río. En el marco del proyecto ECOSUD se llevaron a cabo cinco campañas de muestreo entre julio de 2002 y abril de 2003, en 11 estaciones distribuidas a lo largo de la costa y en el emisor submarino, para determinar la distribución espaciotemporal de la calidad bacteriológica (coliformes fecales, Escherichia coli y enterococos) del agua de mar con la finalidad de detectar posibles áreas peligrosas para usos recreativos y de baño de las playas de la bahía, según los estándares determinados por la Comisión Ambiental Europea. Los resultados obtenidos muestran que, en general, la zona costera de Bahía Cullera mantiene una buena calidad en sus aguas de baño. Sin embargo, la influencia de las descargas tanto del emisario submarino como del Río Júcar tiene un impacto en la zona costera, donde el aumento de la concentración bacteriológica disminuye la calidad de las aguas, sobretodo en los meses de verano cuando la actividad turística es intensa. El aporte adicional de fuentes esporádicas de contaminación en la zona del Cabo Cullera ocasiona un incremento por encima del valor máximo permisible de concentración de bacterias (2000 UFC 100 mL¿1 para coliformes fecales, 200 UFC 100 mL¿1 para enterococos y 500 UFC 100 mL¿1 para E. coli). Además, tomando en cuenta que el patrón de corrientes está controlado por el régimen estacional de los vientos, la zona norte podría llegar a ser una futura fuente adicional de bacterias contaminantes a las zonas de la playa, que hasta hoy mantienen una buena calidad de agua.Cullera Bay, located on the Mediterranean coast of Spain, is influenced by the Júcar River outflow and by an sewage outfall that discharges wastewaters in the vicinity of the river mouth. Within the framework of the ECOSUD project, five sampling campaigns were conducted between July 2002 and April 2003 at 11 stations distributed along the coast of the bay and in the area of the sewage pipe, in order to determine the spatial and temporal distribution of bacteria (faecal coliforms, enterococci and Escherichia coli) in the seawater and thus detect possible dangerous zones for recreational use of the beaches, based on the guidelines established by the European Environmental Commission. In general, Cullera Bay was found to have good water quality; however, the discharges from both the river and sewage outfall affect the coastal zone, the increase in bacterial concentration diminishing the quality of the bathing waters, especially during the summer months when tourism peaks. Moreover, as a result of additional inputs of sporadic sources of pollution in the area of Cape Cullera, the maximum permissible values established for faecal coliforms (2000 CFU 100 mL¿1), enterococci (200 CFU 100 mL¿1) and E. coli (500 CFU 100 mL¿1) were exceeded. Considering that the currents are driven by seasonal winds, the northern area could eventually become an additional source of contaminating bacteria to the beaches that currently have good water qualityCupul-Magaña, L.; Mösso Aranda, C.; Sánchez-Arcilla, A.; Sierra-Pedrico, J.; Fermán-Almada, J.; Romero Gil, I.; Falco Giaccaglia, SL. (2006). Distribución bacteriológica en el agua de mar en la Bahía Cullera, España. Ciencias Marinas. 32(2):311-318. doi:10.7773/cm.v32i21.1058S31131832

The influence of topography on wind-induced hydrodynamics in Cullera bay

[EN] Cullera Bay is an example of a multi-source polluted coastal environment. The water quality in the bay is highly affected by pressure from major agricultural and industrial activities in the river basin. Fresh water is taken from the river and later returned, loaded with pesticides and fertilizers. Partially treated wastewater from riverbank towns and industries is discharged into the lower reaches of the river. This mechanism contributes to river pollution. The dramatic increase in Cullera's population during the summer tourist season and the limited capacity of the local water treatment plant also make it difficult to dispose of domestic wastewater, some of which is discharged untreated into the river or directly into the sea through a marine outfall. This freshwater input from the Júcar River and the marine outfall produces a highly polluted estuarine plume in the coastal region (with significant salinity gradients and complex spatial patterns), which is highly influenced by the hydrodynamics of the bay. Because of the discharge from the Júcar River, the sewage from the marine outfall and the particular geomorphological features of Cullera Bay, this plume may play a significant role in defining and supporting different aspects of the socioeconomic environment in neighboring areas, especially those related to water quality. However, the mean water quality in the bay does not depend only on the surface circulation pattern but also on the overall marine circulation in the water body, where the local bathymetry has more relative influence. Therefore, it is important to have the tools and capabilities needed to monitor and characterize the actual pollutant dispersion drivers (wind and hydrodynamics) to assess their influence at local and regional levels. This paper presents the characterization of the wind field and circulation pattern in Cullera Bay using data acquired during seven field campaigns. The analysis shows that there is strong seasonal behavior in the wind field, ranging from daily breeze patterns to persistent offshore winds. Although the wind field varies greatly throughout the year, the overall pattern mainly consists of daily breezes. However, the hydrodynamic field has proved to be very complex and, with a few exceptions, poorly correlated with the wind-field pattern. This poor correlation may be due to a nonhomogeneous wind field in Cullera Bay caused by a nearby mountainous barrier. Despite the complexity of the hydrodynamic field in each campaign, the overall analysis of the nearshore current pattern shows a strong ¿boundary condition¿ influence that mainly follows the isobaths rather than the wind field. The influence of the topography on the wind and currents may have significant implications for quantifying the relative importance of pollutant sources that harm the quality of the water in Cullera Bay.The European Community funded this study as a part of the ECOSUD project, ‘‘Estuaries and Coastal Areas. Basis and Tools for a More Sustainable Development’’ (reference no. ICA4-CT-2001-10027) and the AQUAS project (‘‘Water quality and sustainable aquaculture. Links and implications’’. Reference no. INCO-CT-2005-015105). It was also funded by a special initiative of the Spanish Ministry of Science and Technology, ‘‘Bases y herramientas para el desarrollo sostenible de zonas costeras y estuarinas’’ (reference no. REN2001-5510-E) and the project ‘‘Desarrollo y optimizacio´n de te´cnicas para gestionar los vertidos de aguas residuales de emisarios submarinos (ARTEMISA)’’ (Reference no. REN2003-07585-C02-01/MAR).Mösso, C.; Sierra, J.; Mestres Ridge, M.; Cupul, L.; Falco Giaccaglia, SL.; Rodilla Alamá, M.; Sánchez-Arcilla, A.... (2007). The influence of topography on wind-induced hydrodynamics in Cullera bay. Journal of Coastal Research. SI 47:17-30. doi:10.2112/1551-5036-47.sp1.17S1730SI 4

Medición de parámetros físicos, biológicos y químicos en el tramo estuarino del río Ebro

[ES] En este artículo se describen las campañas de campo CYTMAR I y II realizadas en la primavera y el verano de 1997, con el fin de estudiar los procesos y los flujos físicos, biológicos y químicos en la zona del Delta del Ebro, tanto en el tramo estuarino del río como en la pluma de agua dulce que se forma en las cercanías de la desembocadura. Aquí el estudio se ha centrado en la zona estuarina, presentando algunos resultados preliminares y analizando las diferencias estacionales observadas.Este trabajo forma parte del proyecto FANS (contrato No. MAS3-CT95-0037) del Programa MAST-III de la Unión Europea y del proyecto MAR96-1856 del Programa CYTMAR de la Comisión Interministerial de Ciencia y Tecnología (CICYT). También se agradece la contribución de todos los que participaron en las campañas de campo. Finalmente cabe destacar la colaboración de la Confederación Hidrográfica del Ebro, que proporcionó los datos de caudales del río y del Centro de Estudios de Puertos y Costas (CEPYC) del CEDEX, que prestó algunos de los equipos utilizados en las campañas.Sierra, J.; González Del Rio Rams, J.; Flos, J.; Sánchez Arcilla, A.; Movellán, E.; Rodilla Alamá, M.; Mösso, C.... (2001). Medición de parámetros físicos, biológicos y químicos en el tramo estuarino del río Ebro. INGENIERIA DEL AGUA. 8(4):459-468. http://hdl.handle.net/10251/36091S4594688