Tidal nitrogen and phosphorus exchange in the Palmones River estuary (Algeciras Bay, Cadiz)

The estuary of the Palmones River is a shallow fluvial catchment area, which had suffered major hydrodynamic changes over the last decade related to the construction of a dam. The estuary acts as a nutrient sink, and its catchment area shows high eutrophication (Pérez-Lloréns, Fernández and Niell, 1989; Clavero, Niell and Fernández, 1997). Nutrient concentration, salinity and evolution of current speed were monitored at the mouth of the estuary during a complete tidal cycle in the spring of 1997. The authors found strong water- column stratification, which enabled them to determine the input and output estuarine fluxes, using a two-box model. The deepest water mass, with a relatively constant composition, is responsible for the nutrient input into the estuary. Surface waters export nutrients to adjacent coastal zones, although this phenomenon has an obvious seasonal component. Net balance reveals a silicate, phosphate and ammonia output and frequent nitrogen forms (nitrite and nitrate) inputs.El estuario del río Palmones es una cuenca fluvial de escasa profundidad que, en la última década, ha sufrido un represamiento, originando importantes cambios en su hidrodinámica. El estuario se comporta como un sumidero de nutrientes y su cuenca experimenta una alta eutrofización (Pérez Lloréns, Fernández y Niell, 1989; Clavero, Niell and Fernández, 1997). Se ha seguido la evolución de la concentración de nutrientes, salinidad y velocidades de corriente en la desembocadura del estuario durante ciclos de marea completos en la primavera de 1997. Debido a la intensa estratificación encontrada en la columna de agua, los flujos de entrada y salida del estuario se han cuantificado mediante un modelo de dos cajas. La masa de agua más profunda, con una composición relativamente constante, es responsable de una entrada de nutrientes en el estuario. Por el contrario, las aguas más superficiales exportan nutrientes a otras zonas adyacentes, aunque este fenómeno tiene una clara componente estacional. El balance neto pone de manifiesto una salida de silicato, fosfato y amonio y una entrada en el sistema de formas asiduas de nitrógeno (nitrito y nitrato).Instituto Español de Oceanografí

The speciation of inorganic carbon in estuarine and interstitial waters

A calculation procedure to obtain pH, total alkalinity and concentration of inorganic carbon, based on the application of Gran functions, is described. An iterative program was used to optimise the electrode standard potential (E₀) and inorganic carbon concentration. Alkalinities higher than 15 mM were detected in interstitial waters from sediments collected in Cadiz Bay. A contribution of 20 % was associated with those acid-based species other than inorganic carbon. Speciation of inorganic carbon in estuarine waters was characterised using laboratory simulation techniques. Total carbonate and alkalinity, as well as inorganic carbon concentration, present conservative behaviour in the mixing process of waters having different salinities.En este trabajo se presenta un procedimiento de cálculo para la obtención del pH, alcalinidad total y concentración de carbono inorgánico, basado en la aplicación de funciones de Gran. Para ello, se ha utilizado un programa iterativo que optimiza el potencial estándar del electrodo y la concentración de carbono inorgánico. Mediante la aplicación de este método se muestran algunas características del sistema del carbónico en el agua intersticial y en sistemas estuáricos. En el agua intersticial de los sedimentos de la bahía de Cádiz se han detectado alcalinidades superiores a 15 mM a profundidades mayores de 10 cm, existiendo una contribución de hasta un 20 % de especies con carácter ácido-base diferentes al carbono inorgánico. La especiación del carbono inorgánico en aguas estuáricas se ha caracterizado utilizando técnicas de simulación en el laboratorio. Se ha observado que tanto la alcalinidad total, como la alcalinidad de carbonato y la concentración de carbono inorgánico presentan un comportamiento conservativo en procesos de mezcla de aguas de diferentes salinidades.Instituto Español de Oceanografí

Hydrochemistry characterisation of protected marine ecosystems in Cadiz

Wetlands have a great natural wealth due to their borderline nature, representing the point where lithosphere, hydrosphere and atmosphere converge. The wetlands of Cadiz, at the southern extreme of Europe, also play an important role as a stopover area for migratory birds. This paper presents the results of a sampling project conducted during the spring of 1997 in the Guadiaro and Palmones Rivers, the Barbate estuary, Sancti Petri sound, and the San Pedro River salt marsh. For each system, three sampling stations were established along a salinity gradient, and these variables were measured: salinity, pH and chloride, sulphate, sodium, potassium, calcium, magnesium, nitrite, nitrate, silicate ammonia, organic carbon, dissolved oxygen, chlorophyll and phaeopigment concentrations. Several behaviours were found for the various systems: the Guadiaro and Palmones Rivers fit a fluvial estuary pattern, with low ionic concentrations and poor remineralisation. The San Pedro River and Sancti Petri sound are tidal systems with a typical seawater composition and high benthic regeneration. The Barbate estuary represents an intermediate scenario between the preceding ones, with a pronounced salinity gradient along its course.Los humedales tienen una gran riqueza natural debido a su carácter de franja donde convergen litosfera, hidrosfera y atmósfera. Los de la provincia de Cádiz, en el extremo meridional de Europa, tienen además una gran importancia como lugar de paso de las aves migratorias. En este trabajo se exponen los resultados obtenidos durante la primavera de 1997 en los estuarios de los ríos Guadiaro y Palmones, el estuario del Barbate, en las marismas del Caño de Sancti Petri y las del río San Pedro. Para cada uno de los sistemas se establecieron tres estaciones de muestreo a lo largo del gradiente de salinidad, y se determinó la salinidad, el pH y las concentraciones de cloruro, sulfato, sodio, potasio, calcio, magnesio, nitrito, nitrato, silicato, amonio, fosfato, carbono orgánico, oxígeno disuelto, clorofila a y feopigmentos. Se encontraron diferentes comportamientos para los distintos sistemas: el Guadiaro y el Palmones responden a un patrón de estuario de tipo fluvial, con concentraciones iónicas muy bajas y una escasa remineralización de la materia orgánica. El río San Pedro y el Caño de Sancti Petri son, por el contrario, sistemas mareales con aguas de comportamiento típicamente marino y una alta regeneración bentónica. El estuario del Barbate es una situación intermedia entre las anteriores y posee un marcado gradiente de salinidades a lo largo de su cauce.Instituto Español de Oceanografí

The influence of urban wastes on the interstitial water chemistry in coastal marine sediments of Cadiz Bay

The authors determined, with visual profiles, the concentration of nutrients (i.e. ammonia, nitrate, phosphate and silica), inorganic carbon and sulphate in the interstitial water of Cadiz Bay, as well as organic carbon in sediment, using samples from three stations on Sancti Petri sound. These three stations suffer from different contamination levels due to untreated urban wastewater. Our results show a degradation of the organic matter, principally in the first 30 cm of sediment. These concentration changes are important in the superficial water layer, indicating the efficiency of aerobic oxidation, the organic matter's principal mineralisation mechanism. Two stations, those nearest to the waste point, had the highest organic carbon concentrations in their sediment, as well as the highest vertical gradients of nutrient concentrations in their interstitial water. Sulphate reduction is the principal mechanism involved in the oxidation of organic matter. On the other hand, at the other station studied, with lower organic carbon levels, the gradients were smoother.Se han caracterizado los perfiles verticales en el agua intersticial de las concentraciones de nutrientes (amonio, nitrato, fosfato y silicato), carbono inorgánico y sulfato, así como de carbono orgánico en el sedimento en tres estaciones del caño de Sancti Petri, sujetas a distinto grado de contaminación por vertidos urbanos sin depurar. Analizando globalmente las variaciones con la profundidad de las concentraciones de las distintas especies estudiadas, se puede afirmar que existe una degradación continuada de la materia orgánica, al menos, en los primeros 30 cm del sedimento. Esta hipótesis se encuentra reforzada por la propia disminución de la concentración de carbono orgánico en el sedimento con la profundidad. Estos cambios de concentración son especialmente acusados en la lámina de agua más superficial, poniendo de manifiesto la eficiencia de la oxidación aeróbica como mecanismo de mineralización de la materia orgánica. Las dos estaciones más próximas al vertido, que poseen concentraciones de carbono orgánico más elevadas en el sedimento, presentan también mayores gradientes verticales de concentración de nutrientes en el agua intersticial, y la sulfatorreducción adquiere una mayor importancia relativa como vía de oxidación de la materia orgánica. Por el contrario, en la estación situada en el extremo sur del caño, menos afectada por los aportes de materia orgánica, se observan gradientes más suaves.Instituto Español de Oceanografí

Factor analysis of linear alkylbenzene sulphonate (LAS) vertical distribution in coastal sediments of Cadiz Bay (southwest Spain)

El comportamiento del alquilbenceno lineal sulfonato (LAS) en los sistemas costeros no se conoce con precisión, y este conocimiento es aun menor si nos restringimos al compartimento sedimentario. En este trabajo se aplica un análisis factorial a los resultados obtenidos para distintas variables determinadas en tres estaciones, tanto en sedimento como en agua intersticial, con el objetivo de evaluar sus interrelaciones con el LAS. Las variables analizadas presentan dos modos principales de distribución con la profundidad en el compartimento sedimentario: lineal y/o exponencial. En casi todos los casos, el LAS se asocia a ambos modos de distribución, lo que indica que su concentración sufre una disminución con la profundidad, pero se produce de forma especialmente acusada en la capa superficial.Very little is known concerning the behaviour of linear alkylbenzene sulphonate (LAS) in coastal systems, and even less when we consider the sedimentary field only. In the present study, a factor analysis is applied to the results obtained for different variables at three stations, both in the sediment and in interstitial water, with the aim of evaluating their relationship with LAS. The variables analysed have two main types of distribution in the sedimentary area in relation to depth: linear and/or exponential. LAS is, in most cases, associated with both types of distribution, indicating that its concentration decreases with depth, especially in the surface layer.Instituto Español de Oceanografí

Development and automation of photobioreactors for microalgae intensive cultures for the use in industrial gas studies

Peer Reviewe

Scutoids are a geometrical solution to three-dimensional packing of epithelia

As animals develop, tissue bending contributes to shape the organs into complex three-dimensional structures. However, the architecture and packing of curved epithelia remains largely unknown. Here we show by means of mathematical modelling that cells in bent epithelia can undergo intercalations along the apico-basal axis. This phenomenon forces cells to have different neighbours in their basal and apical surfaces. As a consequence, epithelial cells adopt a novel shape that we term “scutoid”. The detailed analysis of diverse tissues confirms that generation of apico-basal intercalations between cells is a common feature during morphogenesis. Using biophysical arguments, we propose that scutoids make possible the minimization of the tissue energy and stabilize three-dimensional packing. Hence, we conclude that scutoids are one of nature's solutions to achieve epithelial bending. Our findings pave the way to understand the three-dimensional organization of epithelial organs

Author Correction: Scutoids are a geometrical solution to three-dimensional packing of epithelia.

The original version of this Article contained an error in ref. 39, which incorrectly cited 'Fristrom, D. & Fristrom, J. W. in The Development of Drosophila melanogaster (eds. Bate, M. & Martinez-Arias, A.) II, (Cold spring harbor laboratory press, 1993)'. The correct reference is 'Condic, M.L, Fristrom, D. & Fristrom, J.W. Apical cell shape changes during Drosophila imaginal leg disc elongation: a novel morphogenetic mechanism. Development 111: 23-33 (1991)'. Furthermore, the last sentence of the fourth paragraph of the introduction incorrectly omitted citation of work by Rupprecht et al. The correct citation is given below. These errors have now been corrected in both the PDF and HTML versions of the Article. Rupprecht, J.F., Ong, K.H., Yin, J., Huang, A., Dinh, H.H., Singh, A.P., Zhang, S., Yu, W. & Saunders, T.E. Geometric constraints alter cell arrangements within curved epithelial tissues. Mol. Biol. Cell 28, 3582-3594 (2017)

Tidal and seasonal carbon and nutrient dynamics of the Guadalquivir estuary and the Bay of Cádiz (SW Iberian Peninsula)

To study the effects of the physical environment on carbon and nutrient cycle dynamics on the north-eastern shelf of the Gulf of Cádiz, changes in currents, tides, salinity, temperature, carbon system parameters (fugacity of CO₂ (<i>f</i>CO₂), dissolved organic carbon, dissolved inorganic carbon (DIC) and pH) and other related parameters(dissolved oxygen, total dissolved nitrogen (TDN), nutrients and suspended particulate matter) were measured in transects across the Guadalquivir estuary and Bay of Cádiz mouths. The main objective of this study is to investigate the influence of these inner ecosystems on the carbon and nutrient distributions on the adjacent continental shelf. Three cruises were undertaken in June 2006, November 2006 and February 2007. During the whole study period, Guadalquivir estuary exported components at a rate of 3 Gmol of SiO₂, 4 Gmol of DIN, 3 Gmol of TDN, 31 Gmol of DOC and 604 Gmol of DIC per year. On the other hand, Bay of Cádiz imported 3 Gmol of SiO₂, 1 Gmol of DIN, 2 Gmol of TDN, 33 Gmol of DOC and 562 Gmol of DIC per year. Diurnal variability of <i>f</i>CO₂ could have a potentially important implication on the estimate of air–sea CO₂ fluxes. Tides influence velocity and transport of carbon and nutrients: we found statistically significant differences (<i>p</i> < 0.0001, <i>n</i> = 220) between the flood tide (the mean velocity was 4.85 cm s^&ndash;1) and the ebb tide (the mean velocity was −5.67 cm s^&ndash;1). Biological activity and diurnal changes have also an important role on the carbon and nutrient dynamics. Seasonal carbon and nutrient variations were found. During June, both systems were exporting components to the adjacent continental shelf of the Gulf of Cádiz, whereas in February both systems were importing. Monthly studies should be undertaken to completely understand this dynamic system