Polycyclic aromatic hydrocarbons in commercial fish and lobsters from the coastal waters of Madagascar following an oil spill in August 2009

Concentrations of polycyclic aromatic hydrocarbons were determined in species of commercial fish and lobsters following an oil-spill just off the protected Madagascan coastline. Samples were collected along the coastline within and outside the affected area. Summed PAH concentrations ranged from 1.9 μg kg⁻¹ to 63 μg kg⁻¹ wet weight, but with no higher molecular weight PAHs (>202 Da) being detected. All concentrations of benzo[a]pyrene, benz[a]anthracene and dibenz[a,h]anthracene were <0.1 μg kg⁻¹ wet weight, well within the EU and UK set limits for the protection of human health. Additionally, samples were calculated as the benzo[a]pyrene toxic equivalency quotient (TEQ) and found to be well below the level of concern in relation to health of human consumers. Evaluation of the biota PAH data indicated the origin of PAH was predominantly petrogenic with >80% arising from oil sources. Profile studies indicate a low-level multisource petrogenic contamination probably representing a pre-spill background for the area.     

Aerial electromagnetic sounding of the lithosphere of Venus

Electromagnetic (EM) investigation depths are larger on Venus than Earth due to the dearth of water in rocks, in spite of higher temperatures. Whistlers detected by Venus Express proved that lightning is present, so the Schumann resonances ～10–40 Hz may provide a global source of electromagnetic energy that penetrates ～10–100 km. Electrical conductivity will be sensitive at these depths to temperature structure and hence thermal lithospheric thickness. Using 1D analytic and 2D numerical models, we demonstrate that the Schumann resonances—transverse EM waves in the ground-ionosphere waveguide—remain sensitive at all altitudes to the properties of the boundaries. This is in marked contrast to other EM methods in which sensitivity to the ground falls off sharply with altitude. We develop a 1D analytical model for aerial EM sounding that treats the electrical properties of the subsurface (thermal gradient, water content, and presence of conductive crust) and ionosphere, and the effects of both random errors and biases that can influence the measurements. We initially consider specified 1D lithospheric thicknesses 100–500 km, but we turn to 2D convection models with Newtonian temperature-dependent viscosity to provide representative vertical and lateral temperature variations. We invert for the conductivity-depth structure and then temperature gradient. For a dry Venus, we find that the error on temperature gradient obtained from any single local measurement is ～100%—perhaps enough to distinguish “thick” vs. “thin” lithospheres. When averaging over thousands of kilometers, however, the standard deviation of the recovered thermal gradient is within the natural variability of the convection models, <25%. A “wet” interior (hundreds of ppm H₂O) limits EM sounding depths using the Schumann resonances to <20 km, and errors are too large to estimate lithospheric properties. A 30-km conductive crust has little influence on the dry-interior models because the Schumann penetration depths are significantly larger. We conclude that EM sounding of the interior of Venus is feasible from a 55-km high balloon. Lithospheric thickness can be measured if the upper-mantle water content is low. If H₂O at hundreds of ppm is present, the deeper, temperature-sensitive structure is screened, but the “wet” nature of the upper mantle, as well as structure of the upper crust, is revealed.     

Indigenous Land Management in Peri-Urban Landscapes: An Australian Example

This article examines roles, opportunities, and challenges for Indigenous land management in rapidly developing landscapes through a case study of Bunya Bunya Country Aboriginal Corporation, a not-for-profit organization on the Sunshine Coast, Queensland, Australia. An analysis of data collected through semistructured interviews, participant observation, and analysis of secondary sources reveals that Aboriginal land managers work in a variety of roles to manage issues affecting the local environment and cultural heritage sites. These efforts are challenged by the absence of Native Title and colonial land management policies, which restrict Aboriginal involvement in land management. We conclude that there is a need for alternative pathways to engage with Aboriginal land managers who cannot, or choose not to, proceed with Native Title. Decolonized decision-making tools and sustainable enterprises are viable opportunities that partially address these challenges and could deliver tangible socio-economic and cultural benefits to local Aboriginal and non-Aboriginal people.     

Identifying hot spots of security vulnerability associated with climate change in Africa

Given its high dependence on rainfed agriculture and its comparatively low adaptive capacity, Africa is frequently invoked as especially vulnerable to climate change. Within Africa, there is likely to be considerable variation in vulnerability to climate change both between and within countries. This paper seeks to advance the agenda of identifying the hot spots of what we term “climate security” vulnerability, areas where the confluence of vulnerabilities could put large numbers of people at risk of death from climate-related hazards. This article blends the expertise of social scientists and climate scientists. It builds on a model of composite vulnerability that incorporates four “baskets” or processes that are thought to contribute to vulnerability including: (1) physical exposure, (2) population density, (3) household and community resilience, and (4) governance and political violence. Whereas previous iterations of the model relied on historical physical exposure data of natural hazards, this paper uses results from regional model simulations of African climate in the late 20th century and mid-21st century to develop measures of extreme weather events—dry days, heat wave events, and heavy rainfall days—coupled with an indicator of low-lying coastal elevation. For the late 20th century, this mapping process reveals the most vulnerable areas are concentrated in Chad, the Democratic Republic of the Congo, Niger, Somalia, Sudan, and South Sudan, with pockets in Burkina Faso, Ethiopia, Guinea, Mauritania, and Sierra Leone. The mid 21st century projection shows more extensive vulnerability throughout the Sahel, including Burkina Faso, Chad, Mali, northern Nigeria, Niger, and across Sudan.     

ESR dating of tooth enamel in Mousterian layer 20, El Castillo,Spain

Nine faunal teeth from layer 20 of El Castillo cave in Cantabrian Spain were dated using electron spin resonance (ESR). Two teeth were rejected due to inconsistent subsample ages, while the remaining teeth yielded a mean age that is consistent with the stratigraphic expectations: 42.7±3.5. Uncertainty in the external γ dose rate results in a potential systematic uncertainty of±6.4ka that should affect all samples equally. The results provide independent confirmation of previously reported ¹⁴C ages for layer 20. © 2010 Wiley Periodicals, Inc.     

Lobster trap impact on coral reefs: Effects of wind‐driven trap movement

Commercial fishers report finding their lobster traps often great distances from their original location following major hurricanes. But traps also move during lesser wind events, such as during winter cold fronts. To assess trap impact on coral communities following winter storms, lobster traps were placed in hardbottom and reef habitats commonly used by commercial fishers in the Florida Keys, United States. Trap movement, percentage benthic faunal cover, and benthic faunal damage were assessed after 26 wind events occuring over three winters. Traps moved when storms with sustained winds greater than 15 knots (27.8 km/h) persisted for more than 2 days. Winter storms above this threshold moved buoyed traps a mean (±SE) distance of 3.63 ± 0.62 m, 3.21 ± 0.36 m, and 0.73 ± 0.15 m per trap and affected a mean area of 4.66 ± 0.76 m², 2.88 ± 0.29 m², and 1.06 ± 0.17 m², per trap at 4‐m, 8‐m, and 12‐m depths, respectively. Unbuoyed traps, simulating derelict traps, moved a mean distance of 0.43 ± 0.08 m and 0.44 ± 0.02 m, and affected a mean area of 0.77 ± 0.06 m² and 0.90 ± 0.08 m² per trap at 4‐m and 8‐m depths, respectively. Injuries caused by trap movement included scraped, fragmented, and dislodged sessile fauna, resulting in significant damage to stony coral, octocoral, and sponges. Overall, sessile fauna cover along the trap movement path was reduced from 45% to 31%, 51% to 41%, and 41% to 35% at the 4‐m, 8‐m, and 12‐m sites, respectively. Because of the large numbers of traps deployed and reported lost each season, damage to sessile fauna and loss of benthic faunal cover caused by traps needs to be considered to effectively protect coral reefs and manage essential fishery habitat in the future.