Redescription of the rare species Podospongia loveni (Porifera) from the Cantabrian Sea     

Javier Cristobo  Pilar Ríos  Francisco Sánchez  Nuria Anadón 《Continental Shelf Research》2009,29(8):1157-1164

Podospongia [du Bocage, B., 1869. Eponges siliceuses nouvelles du Portugal et de l’Île Saint-Iago (Archipel de Cap-Vert). Jornal de Sciencias mathematicas, physicas e naturais 2, 159–162], which at present includes only five species, is a rare genus generally found in deeper waters down to 600 m depth from Natal coast in South Africa, to New Caledonia, the Central and North Atlantic and the Mediterranean Sea. Species of this genus are characterised by a choanosomal skeleton composed of tracts of megascleres radiating from a centrum and stipitate body. Microscleres are spinorhabds and aciculospinorhabds packed in a vertical arrangement in the ectosome and scattered throughout choanosome.As a result of two oceanographic projects (Ecomarg, date; Cocace, date) on the continental shelf of the Cantabrian Sea, ten stipitate sponge specimens were collected and assigned to Podospongia loveni [du Bocage, B., 1869. Eponges siliceuses nouvelles du Portugal et de l’Île Saint-Iago (Archipel de Cap-Vert). Jornal de Sciencias mathematicas, physicas e naturais 2, 159–162]. Since the holotype was destroyed [Kelly, M., Samaai, T., 2002. Family Podospongiidae de Laubenfels, 1936. In: Hooper, J.N.A., Soest, RW.M., (Eds.), Systema Porifera: A Guide to the Classification of Sponges, New York, pp. 694–702] and with the existence of several specimens from a close region, we hereby redescribe this species. scanning electron microscopy pictures of the spicules and skeletal architecture of P. loveni are for the first time provided.  相似文献   

The palaeogeographic position of Central Iberia in Gondwana during the Ordovician: evidence from zircon chronology and Nd isotopes     

Fernando Bea  Pilar Montero  Cristina Talavera  Mohamed Abu Anbar  Jane H. Scarrow  José F. Molina  Juan A. Moreno 《地学学报》2010,22(5):341-346

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Spatial and temporal changes in infaunal communities inhabiting soft-bottoms affected by brine discharge   总被引：1，自引：0，他引：1  

Ruso Ydel P  Carretero JA  Casalduero FG  Lizaso JL 《Marine environmental research》2007,64(4):492-503

The discharge of an effluent of high salinity from reverse osmosis desalination plants has a strong impact on marine communities. The aim of this study was to examine the effect of brine discharge over soft bottom communities along the Alicante coast (Southeast Spain) over a two year period. Changes in the infaunal assemblage were analysed using univariate and multivariate techniques. Each year we sampled along three transects at three depths (4, 10 and 15m) during winter and summer. We observed a substitution of a community characterized by the presence of Polychaeta, Crustacea and Mollusca, for another dominated by nematodes (up to 98%), in the stations closer to the discharge where salinity values exceed 39 psu.  相似文献   

Soil-water behaviour of sandy soils under semi-arid conditions in the Duero Basin (Spain)     

Antonio Ceballos  Jos Mart&#x;&#x;nez-Fernndez  Fernando Santos  Pilar Alonso 《Journal of Arid Environments》2002,51(4):501

This paper examines the soil-water behaviour of sandy soils representative of a broad area in the Duero river basin (Spain), with semi-arid bioclimatic characteristics. Soil-moisture measurements of the first 25 cm of soil profile were taken using time domain reflectometry (TDR) methodology. The infiltration process was studied by means of field experiments combining rainfall simulations and TDR techniques. Finally, a set of hydrodynamic variables was calculated in the laboratory (i.e. available soil-water content, soil-water-retention curves and hydraulic conductivity).The average available soil-water content is 0·07 cm³ cm⁻³, in accordance with the predominance of the sandy textural fraction (85%). The rainfall simulation experiments show that infiltration prevails over overland flow, with a steady-state infiltration rate higher than rainfall application (40mmh⁻¹) in most cases; a low water-retention capacity was also observed. The evolution of soil-moisture over time indicates a close dependence on intra-annual rainfall variability due to the low water-retention capacity of sandy soils. With a maximum water-storage capacity of around 0·18 cm³ cm⁻³, the soils studied show high sensitivity to dry spells and may remain with <50% of the available soil-water content for several months during the year.  相似文献   

Effects of freshwater inputs on the lower trophic levels of a temperate estuary: physical, physiological or trophic forcing?     

Enrique González-Ortegón  Pilar Drake 《Aquatic Sciences - Research Across Boundaries》2012,74(3):455-469

The aim of this 6?year study was to assess whether freshwater inputs (rainfall and dam discharges) were acting as physical, physiological or trophic forcing factors on phytoplankton pigment concentrations and the dominant mysids of a temperate estuary (Guadalquivir estuary; SW, Spain). The effects of natural and human-controlled freshwater inputs modified the physico-chemical conditions and consequently biological production (bottom up control). Nutrient (nitrogen hypernutrification), suspended particulate matter and allochthonous photosynthetic pigment imports linked to freshwater inputs from adjacent habitats were observed, as well as light-limited autochthonous primary production. Seasonal and/or spatial patterns were shown by all study variables, including mysids. Freshwater management effects on dominant mysids differed depending on the species?? salinity tolerance (physiological forcing) and preferred prey availability (trophic forcing). Moreover, high inorganic matter content had a negative effect on the density of Mesopodopsis slabberi (physical forcing), which led to an increased detritivory/herbivory ratio (Neomysis integer/M. slabberi ratio). In conclusion, freshwater inputs appeared to effect estuarine lower trophic levels via a combination of different forcing mechanisms. Although several general patterns can be derived, the response of the system to freshwater inputs was not always univocal.  相似文献   

The ~AD1315 Tarawera and Waiotapu eruptions, New Zealand: contemporaneous rhyolite and hydrothermal eruptions driven by an arrested basalt dike system?     

Ian A. Nairn  Jeffrey W. Hedenquist  Pilar Villamor  Kelvin R. Berryman  Phil A. Shane 《Bulletin of Volcanology》2005,67(2):186-193

A series of large hydrothermal eruptions occurred across the Waiotapu geothermal field at about the same (prehistoric) time as the ~AD1315 Kaharoa rhyolite magmatic eruptions from Tarawera volcano vents, 10–20 km distant. Triggering of the Waiotapu hydrothermal eruptions was previously attributed to displacement of the adjacent Ngapouri Fault. The Kaharoa rhyolite eruptions are now recognised as primed and triggered by multiple basalt intrusions beneath the Tarawera volcano. A ~1000 t/day pulse of CO₂ gas is recorded by alteration mineralogy and fluid inclusions in drill core samples from Waiotapu geothermal wells. This CO₂ pulse is most readily sourced from basalt intruded at depth, and although not precisely dated, it appears to be associated with the Waiotapu hydrothermal eruptions. We infer that the hydrothermal eruptions at Waiotapu were primed by intrusion of the same arrested basalt dike system that drove the rhyolite eruptions at Tarawera. This dike system was likely similar at depth to the dike that generated basalt eruptions from a 17 km-long fissure that formed across the Tarawera region in AD1886. Fault ruptures that occurred in the Waiotapu area in association with both the AD1886 and ~AD1315 eruptions are considered to be a result, rather than a cause, of the dike intrusion processes.Editorial responsibility: J. Donnelly-Nolan  相似文献   

Polar motion for an elastic earth model using a canonical theory     

Miguel J. Sevilla  Pilar Romero 《Journal of Geodesy》1985,59(4):396-411

The purpose of this paper is to develop a canonical formulation of the rotational motion for an elastic Earth model. We have obtained the canonical equations for the precession and nutation motion in an inertial frame, and from this we have deduced the equations in an Earth-fixed frame. The linearized equations deduced for polar motion are equivalent to those obtained using Liouville's equations.  相似文献