Amphipoda assemblages in a disturbed area (Alicante,Spain, Western Mediterranean)

The distribution and composition of Amphipoda assemblages were analysed off the coasts of Alicante (Spain, Western Mediterranean), a disturbed area affected by several co‐occurring anthropogenic impacts. Although differences among sampled stations were mainly related to natural parameters, anthropogenic activities were linked with changes in amphipod assemblages. Expansion of the Port of Alicante, a sewage outfall and a high salinity brine discharge could be causing the disappearance of amphipods at stations closer to these disturbances. However, the completion of port enlargement works and mitigatory dilution of the brine discharge has led to the recovery of the amphipod assemblage. Among the natural parameters, depth determines the distribution of some of the species. While Siphonoecetes sabatieri was abundant at shallow stations, Ampelisca spp., Photis longipes, Pseudolirius kroyeri, Apherusa chiereghinii and Phtisica marina were more abundant at deeper stations. Grain size and percentage of organic matter also influenced amphipod distribution, resulting in changes in species composition and in the relative percentages of different trophic groups. Species such as Ampelisca brevicornis, Perioculodes longimanus, Urothoe hesperiae and Urothoe elegans were more abundant at stations with a high content of fine sand. Carnivorous species, mainly of the Oedicerotidae family, were more abundant at those stations with a low organic matter content, while detritivorous species were more abundant at stations with a higher mud content. Among 62 identified species, three were reported for the first time from the Spanish Mediterranean coast, two species were recorded for the second time and a new species of Siphonoecetes was found, Siphonoecetes (Centraloecetes) bulborostrum. These results confirm the need for further data on amphipods from the Mediterranean Spanish coast.     

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

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.     

Spatial and temporal changes in infaunal communities inhabiting soft-bottoms affected by brine discharge

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.     

Les ensembles fluviatiles néogènes du bassin subandin d'Équateur et implications dynamiquesThe Neogene fluvial systems of the Ecuadorian foreland basin and dynamic inferences

A sedimentological study of the Neogene continental infill of the Subandean foreland basin of Ecuador led us to define an evolution of the fluvial system from an alluvial plain to an alluvial fan with an increasing slope in the same time as the drainage changed from mostly longitudinal to transverse. Combined with the data presently available on palaeotopography, exhumation, tectonic evolution and geomorphology, these results enable us to infer that, in contrast with the other Subandean foreland basins of Bolivia and Peru, the progradation of the Neogene alluvial fans proceeded by an overall expansion, associated with a relatively small tectonic shortening and not as a result of the development of successive thrust-related depocentres. This also indicates that the surrection of the Cordillera progressed in Ecuador throughout the Neogene. To cite this article: F. Christophoul et al., C. R. Geoscience 334 (2002) 1029–1037.     

The comparative influence of past management and rainfall on range herbaceous standing crop in east-central Argentina: 14 years of observations

Impacts of six initial treatments and rainfall on maximum above-ground herbaceous standing crop were assessed in 1978 and annually from 1984 to 1992 in rangelands of east-central semi-arid Argentina. Treatments applied in 1977–1978 were: (1) untreated control; (2) burning; (3) herbicide application (shrub control); (4) Old Field 1 or (5) Old Field 2 (areas previously exposed to different degrees of mechanical soil disturbance for 25 years); and (6) overgrazing. Domestic herbivores were excluded thereafter from all treatments until 1993.During 1984–1992, total above-ground herbaceous standing crop often remained greater in both Old Fields than in the other treatments; highest mean values were 2336 and 1640 kg ha⁻¹for Old Field 1 and Old Field 2 treatments, respectively. Lowest total above-ground standing crops in all treatments (M = 296–475 kg ha⁻¹) occurred in 1989, the year with the lowest annual rainfall (257·5 mm). Desirable perennial grasses contributed most (44–100%) to total herbaceous standing crop in all treatments during the study period. Most of this standing crop was made up of the cool-season grassesPiptochaetium napostaense, Poa ligularis, Stipa clarazii, S. papposaandS. tenuis. Annual rainfall was closely related (p< 0·05) to total herbaceous and desirable perennial grass standing crops in most treatments, and accounted for most of the variation in herbage production between years.     

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

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.     

Climate change predictions for South America

Some of the characteristics of predicted climate changes for South America are analysed for the years 2010 and 2050. These predictions are based on the results of three-dimensional Global Circulation Models (GCMs). The results differ between models (GISS, NCAR-CCMs and GFDL), particularly when applied to regional and sub-regional scales and to time scales of less than one-year intervals. It is concluded that these differences are due to the particular structure of each model as well as to the lack of sufficient basic data from the South American sub-continent. The dynamics of vegetation cover play an important role in future water balance changes. The changes in surface temperatures predicted by the GISS model are discussed in relation to changes in the climatic-dynamic base stemming from anthropogenic changes in the vegetation cover.