Simulating the influence of an atmospheric fine inhomogeneous structure on long-range propagation of pulsed acoustic signals

The results of simulating the influence of an atmospheric fine structure on the characteristics of acoustic signals propagating throughout the atmosphere for long distances from their sources are presented. A numerical model of an atmospheric fine inhomogeneous structure within the height range z = 20…120 km is proposed to perform calculations. This model and its numerical parameters are based on the current notions of the formation of an atmospheric fine structure due to internal gravity waves. The numerical calculations were performed using the parabolic-equation method. A spatial structure of the acoustic field and the structure of an acoustic signal at long distances from a pulsed source were calculated. It is shown that the presence of an atmospheric fine structure results in a scattering of acoustic signals and their recording in the geometric shadow region. The results of calculations of signal forms are in a satisfactory agreement with data on signals recorded in the geometric shadow region which is formed at a distance of about 300 km from an experimental explosion.     

Marine protected areas—substantiating their worth

With the UK Marine Bill promoting the creation of a network of marine protected areas and similar commitments in other countries there is a need for tools to assist in their design and management. Although physical science often drives designation, the implementation of marine protected areas also encompasses political and socio-economic issues. This paper focuses on one tool in the armoury of decision-makers: choice experiments. It illustrates its application to the quantification of aspects of socio-economic value not readily incorporated into the evaluation of the costs and benefits of marine protected areas utilising cold-water deep coral reefs off the Republic of Ireland.     

Changing trust relations within the Dutch fishing industry: The case of National Study Groups

This paper focuses on changing trust relationships among fishermen following new governance arrangements. The previous ‘thick’ trust relationships that characterized the Dutch fisheries industry under a neo-corporatist arrangement had resulted in an isolation of local fishermen groups vis-à-vis outsiders. However, under new governance arrangements, in particular the so-called Study Groups, these trust relationships are changing. The establishment of Study Groups, where fishermen from different localities have to cooperate on sustainability innovations in order to receive subsidies, lead to more diversity within the industry, more collaborations across localities and new forms of ‘thin’ trust. As such, these Study Groups can be understood as successful experiments in further opening up of the fisheries community.     

How U.S. ocean policy and market power can reform the coral reef wildlife trade

As the world’s largest importer of marine ornamental species for the aquaria, curio, home décor, and jewelry industries, the United States has an opportunity to leverage its considerable market power to promote more sustainable trade and reduce the effects of ornamental trade stress on coral reefs worldwide. Evidence indicates that collection of some coral reef animals for these trades has caused virtual elimination of local populations, major changes in age structure, and promotion of collection practices that destroy reef habitats. Management and enforcement of collection activities in major source countries such as Indonesia and the Philippines remain weak. Strengthening US trade laws and enforcement capabilities combined with increasing consumer and industry demand for responsible conservation can create strong incentives for improving management in source countries. This is particularly important in light of the March 2010 failure of the parties to the Convention on International Trade in Endangered Species (CITES) to take action on key groups of corals.     

Live (stained) benthic foraminifera from the Rhône prodelta (Gulf of Lion,NW Mediterranean): Environmental controls on a river-dominated shelf

In this paper, we investigate the ecology of live (rose Bengal stained) benthic foraminifera collected at 20 stations ranging from 15 to 100 m depth in the Rhône prodelta (Gulf of Lions, NW Mediterranean). These sites were sampled in September 2006, five months after the Rhône River annual flood. Statistical analyses based on foraminiferal communities (> 150 μm) divide our study area into six main biofacies directly related to environmental conditions. Miliolid species are abundant in the relict prodeltaic lobe which is characterised by sand with low organic matter content. Close to the river mouth, the limited oxygen penetration in the sediment combined with important hydro-sedimentary processes constitute stressful conditions for foraminiferal faunas dominated by opportunistic species (e.g. Leptohalysis scottii). With increasing distance from the river mouth, foraminiferal faunas (e.g. Nonionella turgida, Eggerella scabra) adapted to thrive in sediments enriched in Rhône-derived organic matter under more stable hydro-sedimentary conditions appear. In the distal part of the Rhône River influence, benthic species (e.g. Valvulineria bradyana, Textularia agglutinans) living in fine sediment enriched in both continental and marine organic compounds emerge. At the deepest stations located in the south-eastern part of our study area, benthic foraminiferal faunas (e.g. Bulimina aculeata, Melonis barleeanus, Bigenerina nodosaria) are highly diverse, underlining stable environmental conditions characterised by marine-derived organic matter supplies and relatively deep oxygen penetration depth in the sediment. We also compare foraminiferal faunas sampled in September 2006 with communities sampled in June 2005, one month after the Rhône River annual flood (Mojtahid et al., 2009). This comparison suggests that opportunistic species (e.g. B. aculeata, Cassidulina carinata, V. bradyana) have responded to organic matter inputs related to marine primary production in June 2005.     

Vertical distribution and seasonality of peracarid crustaceans associated with intertidal macroalgae

Spatial patterns and seasonal fluctuations of intertidal peracarids from Tarifa Island, Strait of Gibraltar, were studied over a two-year period (December 2005–December 2007). A total of 25,749 individuals were collected, comprising 46 species. Amphipods were best represented in the total number of species (32) and individuals (89% of numerical abundance) followed by isopods (12 species and 11% abundance) and tanaids (2 species and 1%). The highest number of species was registered in intermediate levels (1–1.5 m) dominated by Corallina elongata, although the highest abundances of peracarids were associated to seaweeds of lower levels (0–1 m) such as Gelidium corneum, Osmundea pinnatifida, Valonia utricularis and a turf of Caulacanthus ustulatus. The most abundant peracarids, Hyale stebbingi, H. schmidti, H. perieri, Stenothoe monoculoides, Caprella penantis, C. grandimana, Dynamene edwardsii and Ischyromene lacazei, were present throughout the whole year during 2006 and 2007. The highest peracarid densities were measured in April–August coinciding with the highest development of seaweeds, just before the maximum values of water temperature measured at the end of summer. Multivariate analyses confirmed a clear zonation of algae and associated peracarids in a vertical gradient, which was maintained stable during the two-year study. Several physical and biological factors may regulate such patterns of peracarid abundance and future experimental studies are necessary to explore the importance of factors such as competition, predation or weather conditions.     

Impact of mega-scale sand extraction on tidal dynamics in semi-enclosed basins: An idealized model study with application to the Southern North Sea

Long-term considerations of repeated and increasing sand extraction on the Netherlands Continental Shelf (North Sea) may lead to the creation of a mega-scale extraction trench in front of the Dutch coast (length hundreds of km, width over 10 km, depth several m). We investigate the impact of such a huge topographic intervention on tidal dynamics, which is a key aspect in hydrodynamics, and indirectly also affecting morphodynamics and ecology.     

A comparative analysis of time–depth relationships derived from scientific ocean drilling expeditions

Marine Geophysical Research - Time–depth relationships (TDR) are required for correlating geological information from drill sites with seismic reflection profiles. Conventional...     

Protracted Environmental Issues on a Proposed Titanium Minerals Development in Kenya's South Coast

This study takes cognizance of the fact that the TIOMIN (TIOMIN Resources Inc. of Canada) project has resulted in controversy over its handling of environmental issues and especially the Environmental Impact Assessment (EIA). The authors address many of the protracted issues that have slowed the development of the mining project in Kwale. The main emphasis is on the impacts of the mining and mineral separation processes on the environment, including the governing legislation, the role of consultation and public participation, and socioeconomic issues. In their public documents TIOMIN has specified neither the type of minerals it wants to extract from the area nor their chemical composition. It is well known, however that the titanium minerals and zircon targeted have impurities of iron, thorium and uranium. In the absence of an Environmental Management Plan, the effects of stockpiling radioactive wastes and other impurities that could possibly lead to environmental degradation in both the terrestrial and marine environments have not been publically addressed. The measures proposed to mitigate ecological damage as a result of the establishment of a minerals processing plant in the area seem inadequate. Pollution resulting from accidental spillage or breakage could have significant impact on marine life and residents living near the mining site. Other issues that have not been addressed satisfactorily pertain to the use of surface and underground water. The area already faces a huge water deficit and the calculations presented on aquifer recharge and stream flow rates do not indicate the large quantities of water that would be required in the mineral processing plant. The project, if approved in its present state, risks violation of international conventions. Furthermore, it could cause a conflict between Kenya and Tanzania in the event of an oil spill at the proposed ship loading facility at Shimoni. The proposed mining area includes the district's most fertile land, is home to many fisherfolk and is a major tourist destination. An analysis of the effects of this project on other available opportunities must be thoroughly understood to ascertain the economic and environmental benefits and costs of the mining venture. The proposed compensation rate of $1,000 per acre, for resettlement for example, appears to be grossly inadequate. Compensation should take into account family size and structure family assets and the cost of relocation.     

Persistent volcanic signature observed around Barren Island, Andaman Sea, India

This study delineates the formation of a warm pool (>34°C) of air to the west (downwind) of the active volcano of the Barren Island during October–November 2005. Barren Island is located in the Sumatra–Andaman region, about 135 km east of Port Blair, and lies within the Burma microplate, the southern tip of which experienced a submarine earthquake (M _w 9.3) causing a tsunami in December 2004. Barren Island is the only volcano, which has shown sustained eruptive activity since shortly after the Great Sumatran Earthquake of December 2004. Our observations require further corroboration to relate how submarine earthquakes activate volcanoes and how far these thermal emissions influence climate changes. Because it links global warming and climate changes to the frequent emissions from a volcano activated by submarine earthquakes, this case study is of special interest to the earth-ocean-atmosphere sciences community.