Groupers on the Edge: Shelf Edge Spawning Habitat in and Around Marine Reserves of the Northeastern Gulf of Mexico     

Felicia C. Coleman  Kathryn M. Scanlon  Christopher C. Koenig 《The Professional geographer》2013,65(4):456-474

The northeastern Gulf of Mexico contains some of the most diverse and productive marine habitat in the United States. Much of this habitat, located on the shelf edge in depths of 50 to 120 m, supports spawning for many economically important species, including groupers. Here, we couple acoustic surveys with georeferenced videography to describe the primary spatial and geologic features of spawning aggregation sites for four economically important species: gag (Mycteroperca microlepis), scamp (M. phenax), red grouper (Epinephelus morio), and red snapper (Lutjanus campechanus), with notes on fish distribution and abundance and spawning activities. We provide information on movement patterns of reef fish determined using acoustic telemetry. Finally, we discuss the possible coupling of geomorphology with hydrographic features to influence the overall productivity of the region and the importance of spatial fishery management in sustaining that productivity.  相似文献   

A Review of “The Tsunami of 2004 in Sri Lanka: Impacts and Policy in the Shadow of Civil War”     

Pradyumna P. Karan 《The Professional geographer》2013,65(4):560-561

Abstract

Zionist geographers in Israel were highly involved in institutionalizing Israel's national identity. In search for interpretative schemes, they were highly committed both to Western paradigms and to Zionist narratives. Until the 1970s, organicist models of regional geography were popular despite contradictions between the use of tragic and comic narratives in Western models and the need to adopt romantic narratives for Zionist purposes. The emergence of historical geography in the 1950s helped to solve these contradictions by adopting a contextual mode of explanation in which the national story has been described in terms of a unique one and as an example for the power of Zionist civilization to transform bewildered nature. During the last two decades, new forms of criticism have emerged that changed the discourse from a particularistic story of nation building to a more general story of colonization and territorial control.  相似文献   

The Production of Investment Returns in Spatially Extensive Financial Markets     

Gordon L. Clark  Ashby H. B. Monk 《The Professional geographer》2013,65(4):595-607

Investment returns are produced by combining financial assets with human capital, the decision-making protocols of investment houses, and the electronic infrastructure that supports the flow of information about investment. At the center of the production process stand senior managers; their power and authority in the production process is fundamental to the performance of investment organizations. This article provides a model of the production of investment returns in financial centers and spatially extensive financial markets. We begin with Coase's theory of the firm but go beyond models of the firm that represent commodity-producing industries. Having substantiated the model of investment management, it is applied to institutions that seek investment returns in geographically extensive financial markets. Operating in financial markets at a distance from home jurisdictions is an increasingly important aspect of investment management. Given recent turmoil in global financial markets, financial houses have sought higher rates of return from markets in which they have little direct experience. At issue is how different types of financial organizations (large and small, growing and declining) produce investment returns in this new environment.  相似文献   

Species diversity and regeneration of native species in Pennisetum ciliare (buffelgrass) pastures from the thornscrub of Sonora,México     

《Journal of Arid Environments》2013

To examine the influence of buffelgrass land conversion and pasture management on native species diversity and regeneration patterns, we describe community attributes and population structure in four different active pastures in thornscrub vegetation from eastern Sonora, Mexico. We compare a relatively undisturbed thornscrub community with a contiguous five years old active pasture, to identify species able to regenerate under current management practices. Buffelgrass conversion has a significant influence on species diversity and other community attributes. Active pastures have lower species diversity, crown cover and basal area of native species than the studied native thornscrub. An active pasture subjected to heavy grazing and without management of the thorny legume, Acacia cochliacantha, showed the lower species diversity and an almost monospecific stand of this legume. It is likely that the reduction in species diversity is caused by the conversion process, inadequate management and regeneration barriers that limit seedling establishment in active pastures. Our data recorded eight native species (13%) that were able to regenerate in active pastures. However, the great majority of native species were unable to regenerate under pastures. This study shows that under current management, active buffelgrass pastures maintain only a small fraction of native species with regenerating populations in the thornscrub.  相似文献   

Disruption rates for one vulnerable soil in Organ Pipe Cactus National Monument,Arizona, USA     

《Journal of Arid Environments》2013

Rates of soil disruption from hikers and vehicle traffic are poorly known, particularly for arid landscapes. We conducted an experiment in Organ Pipe Cactus National Monument (ORPI) in western Arizona, USA, on an air-dry very fine sandy loam that is considered to be vulnerable to disruption. We created variable-pass tracks using hikers, an all-terrain vehicle (ATV), and a four-wheel drive vehicle (4WD) and measured changes in cross-track topography, penetration depth, and bulk density. Hikers (one pass = 5 hikers) increased bulk density and altered penetration depth but caused minimal surface disruption up to 100 passes; a minimum of 10 passes were required to overcome surface strength of this dry soil. Both ATV and 4WD traffic significantly disrupted the soil with one pass, creating deep ruts with increasing passes that rendered the 4WD trail impassable after 20 passes. Despite considerable soil loosening (dilation), bulk density increased in the vehicle trails, and lateral displacement created berms of loosened soil. This soil type, when dry, can sustain up to 10 passes of hikers but only one vehicle pass before significant soil disruption occurs; greater disruption is expected when soils are wet. Bulk density increased logarithmically with applied pressure from hikers, ATV, and 4WD.  相似文献   

From cod to shellfish and back again? The new resource geography and Newfoundland's fish economy     

《Applied geography (Sevenoaks, England)》2013

This paper traces three key phases in Newfoundland's resource economy: the collapse of cod, the rise of shellfish and recent efforts to re-establish cod. I argue that these changes in the province's fish economy may be productively understood through the ‘new resource geography’. The paper explores three themes: the relationship between knowledge practices and resource management; the way in which fish resources are defined in both material and discursive forms; and the different sites and institutions involved in the regulation of the cod resource.  相似文献   

The importance of spatial nested data in understanding the relationship between visitor use and landscape impacts     

《Applied geography (Sevenoaks, England)》2013

As managers and researchers of protected natural areas continue to seek balance in promoting visitor use but limiting negative experiential and natural resource impacts, the integration of social and physical spatial data may play a critical role in understanding how visitors and the community interface with the landscape within these protected areas. These spatial considerations are important for inventorying, monitoring, and managing the conditions of natural resources within parks. Specifically related to the visitor impacts of natural resources in parks are the use and condition of multiple-use trails. Technology such as GPS and GIS may allow for a unique assessment of the relationship between factors that influence this resource. This paper focuses on how visitor use distribution (measured through GPS tracking), activity type, and trail design influence the impacts to trail conditions. This paper also addresses statistical concerns related to spatial dependency. Results suggest that failure to account for spatial dependency can lead to erroneous Type I findings. Additionally, activity type (specifically horseback riders) and trail design were found to best predict trail impacts when controlling for spatial dependency.  相似文献   

Understanding and managing the morphology of branches incising into sand-clay deposits in the Dutch Rhine Delta     

Kees SLOFF  Ary VAN SPIJK  Esther STOUTHAMER  Arjan SIEBEN 《国际泥沙研究》2013,28(2):127-138

In the Rhine-Meuse delta in the south-western part of the Netherlands,the morphology of the river branches is highly dependent on the erodibility of the subsoil.Erosion processes that were initiated after closure of the Haringvliet estuary branch by a dam(in 1970),caused a strong incision of several connecting branches.Due to the geological evolution of this area the lithology of the subsoil shows large variations in highly erodible sand and poorly erodible peat and clay layers.This study shows how the geological information can be used to create 3D maps of the erodibility of the sub-soil, and how this information can be used to schematize the sub-soil in computational models for morphological simulations.Local incisement of sand patches between areas with poorly erodible bed causes deep scour holes,hence increasing the risk on river-bank instability(flow slides) and damage to constructions such as groynes,quays,tunnels, and pipelines.Various types of mathematical models,ranging from 1D(SOBEK) to quasi-3D(Delft3D) have been applied to study the future development of the river bed and possible management options.The results of these approaches demonstrate that models require inclusion of a layer-bookkeeping approach for sub-soil schematization, non-uniform sediment fractions(sand-mud),tidal and river-discharge boundary conditions,and capacity-reduction transport modeling.For risk-reducing river management it has been shown how the development of the river bed can be addressed on a large scale and small scale.For instance,the use of sediment feeding and fixation of bed can be proposed for large-scale management,while monitoring and interventions at initiation of erosion can be proposed as response to small-scale developments that exceed predefined intervention levels.  相似文献   

Climate change impact on water resources availability: case study of the Llobregat River basin (Spain)     

P.-A. Versini  L. Pouget  S. McEnnis  E. Custodio  I. Escaler 《水文科学杂志》2013,58(14):2496-2508

ABSTRACT

Climate change may have significant consequences for water resources availability and management at the basin scale. This is particularly true for areas already suffering from water stress, such as the Mediterranean area. This work focused on studying these impacts in the Llobregat basin supplying the Barcelona region. Several climate projections, adapted to the spatiotemporal resolution of the study, were combined with a daily hydrological model to estimate future water availability. Depending on the scenario and the time period, different assessment indicators such as reliability and resilience showed a future decrease in water resources (up to 40%), with drought periods becoming more frequent. An additional uncertainty analysis showed the high variability of the results (annual water availability ranging from 147 hm³/year to 274 hm³/year), thus making accurate projections difficult. Finally, the study illustrates how climate change could be taken into account to provide adaptive measures for the future.