Genetic impact of the Prestige oil spill in wild populations of a poor dispersal marine snail from intertidal rocky shores

In November 2002, the sinking of the Prestige cargo ship produced an oil spill of 60,000 tons that affected many areas along the Galician coast (in the northwest of Spain). In a number of rocky shore sites, most organisms (particularly marine mollusks) were nearly extinct at a local scale. We tested whether the local bottleneck/extinction that occurred in affected localities caused any detectable reduction of the genetic diversity in the marine snail Littorina saxatilis, an ovoviviparous rocky shore model species characterized by a low dispersal ability, high population density, and wide distribution range. We compared the level of genetic variation and population differentiation between affected (polluted) and control sites located in seven geographical areas (three sites per area, one impacted and two controls, and two replicates per site) one and a half years after the spill. The analysis included molecular marker variation (microsatellite and AFLP loci) and quantitative trait genetic variation for shell variables in embryos extracted from pregnant females. Our results indicate that the affected populations did not show a significant overall reduction in genetic diversity when compared to the controls, suggesting that the species is highly resistant to losing genetic variability as a consequence of a local short-term pollution process in spite of its low dispersal ability and direct development. However, some genetic effects were detected in the polluted populations, particularly for quantitative shell traits and AFLPs, consistent with local adaptations resulting from the fuel contamination.     

Long-term Observations for Monitoring Extremes in the Americas

In this paper we discuss data available from Argentina, Mexico, the United States and Canada that are suitable for the analysis of extreme temperature and precipitation events. We also discuss some of the problems of homogeneity and quality control that can potentially affect the observation of extreme values. It is clear that even in countries like the United States and Canada that have a potentially rich source of climate data there are still problems in obtaining homogeneous data necessary to perform thorough studies of time varying changes in extreme events. These types of problems may be compounded if data are needed from countries that do not have a tradition of maintaining large climate archives or observing networks.We also provide two examples of analyses that can be performed with these types of data: (1) the development of climate extremes indices for Canada, and (2) analyses of freezing events for Florida and the effect on the citrus industry. The Canadian example provides a good basis for countries to take indices developed for one country or region and through minor modifications make the index relevant to their own needs. The analysis of freezing events in Florida is a timely example of how extreme events have both ecological and societal impact.     

Morphotectonic zones along the coast of the Pacific continental margin, southern Mexico

Geomorphic analysis, employing topographic, morphologic, geologic, and bathymetric maps, and field studies show that the morphology of the southern coast of Mexico can be linked to lateral variations in the geometry and tectonism of the subduction zone. A reconnaissance study, based on the regional morphological characteristics and correlation with seismotectonic segments, regional tectonics and major bathymetric features, allows identification of several morphotectonic zones along the coast of southern Mexico: (1) Jalisco zone, (2) Colima zone, (3) Michoacan zone, (4) Guerrero zone, (5) Oaxaca zone, and (6) Tehuantepec zone. A range of geomorphological evidence, including marine terraces, river terraces, uplifted notches, and elevated wave-cut platforms, indicates local and regional uplift along the coast of the Jalisco, Michoacan, Guerrero and Oaxaca zones. Coasts of the Colima and Tehuantepec zones show morphological evidence of subsidence.     

Changes in solar irradiance and atmospheric turbidity in Costa Rica during the total solar eclipse of July 11, 1991

Solar global radiation was measured in several places in Costa Rica during the total solar eclipse that occurred on July 11, 1991. In two of these places, Puntarenas and Santa Cruz, measurements in the ultraviolet range (295–385 nm) were also taken. In Santa Cruz, a normal incidence pyrheliometer with Schott filters OG530 and RG630 was used to measure direct solar radiation in its whole range, and in the 530–2800 nm and 630–2800 wavebands respectively. Global radiation, and consequently direct, diffuse and irradiance in any of the wavebands considered, decreased gradually as the sun was being eclipsed and reached zero during the totality, then increased to their normal values. Data registered in Santa Cruz were used to determine Ångstrom's atmospheric turbidity parameters and. Computations show that between 13:00 and 14:30 LT (local time), decreased and increased significantly. This indicates that atmospheric turbidity was high and large particles were more abundant than small ones. The size of hygroscopic particles increased during the eclipse when temperature decreased and relative humidity increased in a comparatively short time.     

SHIA_Landslide: a distributed conceptual and physically based model to forecast the temporal and spatial occurrence of shallow landslides triggered by rainfall in tropical and mountainous basins

Landslides are a main cause of human and economic losses worldwide. For this reason, landslide hazard assessment and the capacity to predict this phenomenon have been topics of great interest within the scientific community for the implementation of early warning systems. Although several models have been proposed to forecast shallow landslides triggered by rainfall, few models have incorporated geotechnical factors into a complete hydrological model of a basin that can simulate the storage and movement of rainwater through the soil profile. These basin and full hydrological models have adopted a physically based approach. This paper develops a conceptual and physically based model called open and distributed hydrological simulation and landslides—SHIA_Landslide (Simulación HIdrológica Abierta, or SHIA, in Spanish)—that is supported by geotechnical and hydrological features occurring on a basin-wide scale in tropical and mountainous terrains. SHIA_Landslide is an original and significant contribution that offers a new perspective with which to analyse shallow landslide processes by incorporating a comprehensive distributed hydrological tank model that includes water storage in the soil coupled with a classical analysis of infinite slope stability under saturated conditions. SHIA_Landslide can be distinguished by the following: (i) its capacity to capture surface topography and effects concerning the subsurface flow; (ii) its use of digital terrain model (DTM) to establish the relationships among cells, geomorphological parameters, slope angle, direction, etc.; (iii) its continuous simulation of rainfall data over long periods and event simulations of specific storms; (iv) its consideration of the effects of horizontal and vertical flow; and (vi) its inclusion of a hydrologically complete water process that allows for hydrological calibration. SHIA_Landslide can be combined with real-time rainfall data and implemented in early warning systems.     

Identification of groundwater exfiltration,interflow discharge,and hyporheic exchange flows by fibre optic distributed temperature sensing supported by electromagnetic induction geophysics

Water exchange across the sediment–water interface of streams impresses a characteristic thermal pattern at the interface. The use of fibre optic distributed temperature sensing at the sediment–water interface in a small sand‐bed stream identifies such temperature patterns. Groundwater and interflow can be differentiated based on the temporal evolution of temperature patterns. Additionally, sudden temperature changes at the sediment–water interface observed during the transit of floods enable spatial identification of local up and downwelling. Electromagnetic induction geophysics can detect subsurface texture structures that support groundwater–surface water exchange. Our results show that areas of permanent temperature anomalies observed with fibre optic distributed temperature sensing match areas of comparatively homogeneous electrical conductivity. This indicates groundwater discharge and enables differentiating groundwater discharge from interflow and local downwelling.     

Oil exploration in the Southern Gulf of Mexico and the Chicxulub impact

Discovery of the Chicxulub multi-ring impact crater came as a result of oil exploration surveys in the southern Gulf of Mexico. Subsequent studies on the Chicxulub impact and the Cretaceous/Palaeogene (K/Pg) boundary have revealed links between the impact and hydrocarbons, with implications for the K/Pg global environmental and climatic effects, as well as for oil exploration in the Gulf.     

Peering inside the peak ring of the Chicxulub Impact Crater—its nature and formation mechanism

The IODP‐ICDP Expedition 364 drilled into the Chicxulub crater, peering inside its well‐preserved peak ring. The borehole penetrated a sequence of post‐impact carbonates and a unit of suevites and clast‐poor impact melt rock at the top of the peak ring. Beneath this sequence, basement rocks cut by pre‐impact and impact dykes, with breccias and melt, were encountered at shallow depths. The basement rocks are fractured, shocked and uplifted, consistent with dynamic collapse, uplift and long‐distance transport of weakened material during collapse of the transient cavity and final crater formation.