La biblioteca universitaria de Las Palmas de Gran Canaria: recursos y servicios

Presentaci��n y conferencia realizada por D��a. Mar��a del Carmen Mart��n Marichal, Directora de la Biblioteca Universitaria de la ULPGC, realizada el 22 de abril de 2008 con motivo de los actos de Inauguraci��n de Mediateca de Casa Africa.

Temporal and along-shelf distribution of the larval fish assemblage at Gran Canaria, Canary Islands

Temporal and spatial variations of the larval fish community off the island of Gran Canaria (Canary Islands) were studied in weekly surveys from October 2005 to June 2006. A total of 156 taxa, belonging to 51 families and 15 orders, were identified. Myctophidae was by far the most abundant family (30%), followed by Sparidae (11%), Clupeidae (9%) and Gonostomatidae (7%). As expected for an oceanic island, neritic and oceanic taxa contributed in similar proportions. Leeward and windward retention areas were found for total egg and neritic larval abundance. However, seasonality showed a stronger influence on the annual larval assemblage than sampling site, as the latter was not significant on a long time scale. Results suggest that there are two seasonal larval assemblages corresponding to the two main characteristic periods of the water column in these waters: mixing (winter) and stratification (summer). In addition, a significant relationship was recorded between lunar illumination and small mesozooplankton biomass, suggesting that this relationship may be extended to certain neritic families. The most abundant neritic larvae (Sparidae) showed this lunar pattern, which partially supports a recent hypothesis about the effect of lunar illumination on larval fish survival and development in subtropical waters.

Modelo de flujo en un acu��fero volc��nico : el Acu��fero de la Aldea (Gran Canaria)

RESUMEN. Se ha llevado a cabo un modelo de flujo de aguas subterr��neas en la desembocadura del Barranco de La Aldea (Gran Canaria). El ��rea fue discretizada tridimensionalmente en celdas de 50x50 m considerando 3 capas. La capa superior est�� constituida por materiales sedimentarios y volc��nicos (aluvial, derrubios de ladera y basaltos alterados) y las capas intermedia e inferior por basaltos. Se ha realizado un modelo en r��gimen estacionario simulando el a��o hidrol��gico medio 1991/92 y transitorio para el per��odo de 1991/92-1998/99. Los l��mites norte, sur y este se han definido como bordes impermeables, la l��nea de costa se ha definido como nivel constante y la cabecera del barranco se ha simulado mediante un tramo de caudal prefijado representando el aporte de la cuenca alta del barranco. Las entradas en la zona son: recarga por lluvia, retornos de riego, p��rdidas en la red de abastecimiento, cabecera del barranco principal y desde la zona de intra-caldera. Las salidas son: bombeos y descarga al mar. El borde inferior se define por el flujo nulo en el contacto entre los basaltos alterados y sin alterar. En el cauce de los barrancos se ha impuesto una condici��n de dren y las extracciones se han localizado seg��n los datos obtenidos de las captaciones de la zona. Los par��metros resultantes de la calibraci��n del modelo, en particular, la transmisividad, son del mismo orden que los obtenidos en estudios previos modelo. Por otro lado, los niveles calculados y observados presentan un buen ajuste y el balance h��drico resulta consistente. ABSTRACT. A groundwater flow model in La Aldea ravine lower part (Gran Canaria) has been developed. The zone has been tridimensionally discretized as cells of 50 x 50 m considering 3 layers. The superficial layer is formed by sedimentary and volcanic materials (Alluvial, screes and altered basalts) and the intermediate and lower layers are basalts. The model has been developed in stationary state for the average hydrologic year 1991/92 and in transitory state for the period of 1991/92-1998/99. The North, South and East limits have been defined as null flow boundary conditions, the coast line has been defined as constant level and the ravine bed at the east has been defined as a constant flow, representing the contribution from the upper ravine basin. Recharge is a result of rainfall, irrigation returns, supply network leaks and inflow from the intra-caldera zone. Discharge takes place by pumping wells and flows towards the sea. The bottom surface is defined as a null flow condition in the limit between altered and unaltered basalts. A drain condition has been imposed in the ravine and the pumping wells extraction has been located. The simulation results indicate that the transmisivities obtained in previous works present the same order of magnitude than the obtained in the model and the calculated levels are in good agreement with the observed levels measurements.

Elaboraci��n de un mapa de lixiviaci��n de nitratos mediante una metodolog��a de acople SIG-modelo de simulaci��n : aplicaci��n al acu��fero de La Aldea (Gran Canaria)

[ES] La contaminaci��n difusa por nitrato constituye una de las mayores amenazas actuales para la calidad de las aguas subterr��neas. De hecho, varias directivas europeas, nacionales y regionales se han legislado con el fin de minimizar el efecto de las pr��cticas agrarias en la contaminaci��n de los acu��feros por nitratos. El acu��fero de La Aldea (Gran Canaria, Espa��a) se ha declarado como vulnerable a la contaminaci��n por nitrato seg��n dichas normas. En este estudio se presenta una metodolog��a para desarrollar el acople de un sistema de informaci��n geogr��fica-SIG con el modelo de simulaci��n de nitrato GLEAMS. Esta herramienta permite calcular la cantidad de nitrato lixiviado procedente de los cultivos de tomate bajo invernadero y da la oportunidad de simular otros rangos de fertilizaci��n para minimizar el riesgo de contaminaci��n de las aguas subterr��neas. Se comprueba que la p��rdida de nitrato por lixiviaci��n en la zona a partir de dichos cultivos pod��a llegar a los 500 kg N/ha, casi un 62% del aportado como fertilizante mineral en un manejo tradicional. Por ello, se aconseja la aplicaci��n de las recomendaciones de abonado incluidas en el c��digo de buenas pr��cticas agrarias de Canarias o cualquier otro sistema de recomendaci��n de abonado mineral para reducir estas p��rdidas, minimizando de esta forma el riesgo de contaminaci��n de las aguas subterr��neas. ABSTRACT: Nitrate diffuse pollution is one of the main risks that affect the groundwater quality. Several european directives, national and regional guidelines have been enacted to protect the aquifers against the effect of the agricultural management practices. The ���La Aldea��� aquifer was declared nitrate vulnerable area following these laws. In this study a methodology was developed to link a Geographical Information System (GIS) with a nitrogen simulation model (GLEAMS) in this area. This tool allows to assess the amount of nitrate leaching that coming from the traditional nitrogen fertilization rates in greenhouses tomato crops, and gives the opportunity to simulate other fertilization rates to reduce the risk of groundwater pollution. The nitrate leaching reached to 500 kg N/ha in several zones of the study area, that represent the 62% of the nitrogen fertiliser apply in a traditional management. It was recommended the application of the Code of Good Management Practices or other recommendation system to decrease the nitrate leaching, in order to reduce the risk of groundwater pollution.

Variaci��n de la comunidad de "Alsidium corallinum" C. Agardh y sus ep��fitos en Pozo Izquierdo, Gran Canaria, Islas Canarias (Rhodomelaceae, Rhodophycota)

ABSTRACT: The community of Alsidium corallinum C Agardh has been studied in Punta Gaviota and Punta del Corral zones (Pozo Izquierdo, Gran Canaria) during an annual cycle. The annual variation of thallus size were analized, resulting that the biggest thallus weregrowing in autumn and smallest were growing in spring. 36 epiphytics species were identified: 18 belong to Rhodophycota, 8 belong to Chromophycota and 10 Chlorophycota. During the spring and summer there were more epiphytic species presentas well as their covering were the highest. RESUMEN: Se estudiaron las poblaciones de Alsidiunz coralli~zumC . Agardh en las zonas de Punta Gaviota y Punta del Corral (Pozo Izquierdo, Gran Canaria, Islas Canarias), a lo largo de un ciclo anual. Se analizo la variaci��n anual de la talla de los talos, siendo ��sta m��nima en primavera y m��xima en oto��o-invierno. Se reconocieron un total de 36 especies ep��fitas, 18 de las cuales pertenecen a la divisi��n Rhodophycota, 8 a la divisi��n Chromophycota y 10 a la divisi��n Chlorophycota. Los talos presentaron mayor n��mero de especies ep��fitas en primavera-verano, as�� como una mayor cobertura por parte de las mismas. Asimismo se observ�� una mayor decoloraci��n de los talos coincidente con la ��poca del a��o en que la presencia de ep��fitos es m��nima.

Geolod��a Gran Canaria 2010

Gu��a de la excursi��n geol��gica al Barranco de Tamaraceite y los Volcanes de Bandama a celebrar en el acto del Geolod��a Gran Canaria 2010