Is the Western and Central Pacific Fisheries Commission meeting its conservation and management objectives?     

Hannah Parris 《Ocean & Coastal Management》2010,53(1):10-26

The Convention of the Conservation and Management of Highly Migratory Fish Stocks in the Western and Central Pacific Ocean is a remarkable achievement in international fisheries cooperative management and significant, albeit slow and uneven, progress has been made by its Commission in promoting the conservation of vulnerable tuna stocks and managing fishing capacity. This paper evaluates current progress and suggests that further progress will be difficult to achieve unless attention is given to addressing the inherent risks in fisheries management and in the underlying incentives facing WCPFC members. Both issues could be addressed over the longer term by drawing on the strengths of existing management strategies that are actively debated within the WCPFC.  相似文献   

Spatial and temporal water column and streambed temperature dynamics within an alpine catchment: implications for benthic communities     

Lee E. Brown  David M. Hannah  Alexander M. Milner 《水文研究》2005,19(8):1585-1610

Despite the significant influence of temperature upon alpine stream benthic communities, thermal regimes of the water column and hyporheic zone of these mountain streams have received limited attention. This paper reports upon a detailed spatio‐temporal study of water column and streambed temperatures undertaken within the Taillon–Gabiétous catchment, French Pyrénées, that aims: (1) to characterize the nature and dynamics of alpine stream water column and streambed thermal patterns; (2) to investigate stream thermal variability under a range of hydroclimatological conditions; and (3) to consider the implications of (1) and (2) for alpine stream benthic communities. The catchment contains four highly dynamic hydrological sources and pathways: (1) two cirque glaciers (Taillon and Gabiétous); (2) seasonal snowpacks; (3) a karst groundwater system; and (4) hillslope aquifers. Water column temperatures were monitored continuously at four sites located along the Taillon glacial stream and at three groundwater springs (two karstic and one hillslope) over the 2002 summer melt season. An eighth site (Tourettes) was established on a predominantly groundwater‐fed stream with limited meltwater input. Bed temperatures (0·05, 0·20 and 0·40 m depth) and river discharge were measured at three sites: (1) the Taillon stream; (2) the Tourettes stream; and (3) below the confluence of (1) and (2). Air temperatures, incoming short‐wave radiation and precipitation were recorded to characterize atmospheric conditions. Glacial stream water column temperatures increased downstream, although groundwater tributaries punctuated longitudinal patterns. Karstic groundwater streams were cooler and more thermally stable than the glacial stream (except at the glacier snout). Hillslope groundwater stream temperatures were most variable and, on average, the warmest of all sites. Streambed temperatures in the glacial stream were coldest and most variable whilst the warmest and least variable streambed temperatures were recorded in an adjacent groundwater tributary. Temperature variability was strongly related to: (1) dynamic water source and pathway contributions; (2) proximity to source; and (3) prevailing hydroclimatological conditions. The high thermal heterogeneity within this catchment may sustain relatively diverse benthic communities, including some endemic Pyrénéan macroinvertebrate taxa. Copyright © 2004 John Wiley & Sons, Ltd.  相似文献   

Mapping land cover change of the Luvuvhu catchment, South Africa for environmental modelling     

Hannah R. Griscom  Scott N. Miller  Thomas Gyedu-Ababio  Ramesh Sivanpillai 《GeoJournal》2010,75(2):163-173

Considerable land cover changes have occurred in the Luvuvhu catchment in northeastern South Africa in the past two decades. These changes are associated with human population growth and may be contributing to observed reductions in winter river baseflows and increased episodes of river drying within Kruger National Park. Six-class land cover maps of the catchment were created from 1978 (MSS) and 2005 (TM) Landsat imagery using an iterative technique. Results indicate a 1,000 km² (12%) increase in Bare Ground between 1978 and 2005, with a concomitant decrease in shrubland and indigenous forest cover. Overall classification accuracy in the 2005 image was 80%. Classification was most accurate for Water and Pine classes (100 and 92%) and least accurate for Indigenous Forest (46%), primarily due to misclassification as Shrubland. These maps are suitable for land cover change and landscape modeling analyses, and can serve as baseline data for further research.  相似文献   

Re-Os study of Fe-Ti-V oxide and Fe-Cu-Ni sulfide deposits, Suwałki Anorthosite Massif, northeast Poland   总被引：1，自引：0，他引：1  

J. W. Morgan  H. J. Stein  J. L. Hannah  R. J. Markey  J. Wiszniewska 《Mineralium Deposita》2000,35(5):391-401

The Suwałki anorthosite massif, located in extreme northeast Poland beneath more than a kilometer of Phanerozoic cover, hosts major Fe-Ti-V deposits. These deposits, discovered in 1962, are contained in Fe and Ti oxide minerals that coexist with subordinate quantities of Fe, Cu, Ni, and Co sulfides in massif-style anorthosites, norites, and gabbronorites. Accessibility and other considerations preclude development of this natural resource in the present economic climate. Detailed work by Polish geologists during the last 35 years provides a sound geologic framework for this Re-Os study of the age and origin of oxide and sulfide deposits associated with a major, but lesser known anorthosite massif. Rhenium and osmium abundances and Os isotopic compositions were measured for nine sulfides and four titanomagnetites from the Suwałki anorthosite massif. The titanomagnetites are over an order of magnitude lower in Re (0.4–1.5 ppb) and Os (0.036–0.144 ppb) concentrations than co-precipitated pyrrhotite, pyrite, and chalcopyrite that yield consistent concentrations for Re (30–55 ppb) and Os (1–6 ppb). Parallel lines connecting co-existing titanomagnetite and sulfides have slopes of ∼1 on Re versus common Os concentration plots, indicating that both Re and Os behave similarly during crystallization in their high preference for any sulfide phase over magnetite. Samples from three deposits within the anorthosite massif were analyzed. An age of 1559 ± 37 Ma (n=10) with an initial ¹⁸⁷Os/¹⁸⁸Os of 1.16 ± 0.06 for the Jezioro Okrągłe and Krzemianka deposits is essentially identical to an age of 1556 ± 94 Ma (n=3) for the Udryń deposit. Udryń, however, yielded a marginally lower initial ¹⁸⁷Os/¹⁸⁸Os of 0.87 ± 0.20. The high initial ¹⁸⁷Os/¹⁸⁸Os combined with the Proterozoic Re-Os age indicates that the source for Suwałki oxides-sulfides is older crust, and hypothetically, could involve Archean rocks. An average crustal value of 50 for ¹⁸⁷Re/¹⁸⁸Os yields a 2777 Ma age for Suwałki source rocks. Widespread Phanerozoic cover severely limits knowledge of basement rocks in Poland, however, and no Archean rocks are known in the immediate region. More likely, ¹⁸⁷Re/¹⁸⁸Os ratios may be higher than average continental crust, reflecting mafic crust in the source, and may move the source age for Suwałki anorthosite and mineral deposits toward younger values that easily include ∼2.0 Ga Proterozoic rocks. This more favorable case also accommodates Paleoproterozoic Nd model ages. Regardless of Archean or Proterozoic source age, the high initial ¹⁸⁷Os/¹⁸⁸Os ratios derived from the Re-Os isochron indicate that the source for the oxide-sulfide mineral deposits is more likely the crust and not the mantle. Given that these deposits are clearly magmatic, the Re-Os results add a new dimension to the long-standing “origin of anorthosite” problem, implying a crustal source for the anorthosite as well. The 1559 Ma Suwałki age is compatible with a well-exposed east-west band of 1530-1660 Ma rapakivi granite-anorthosite magmatism to the immediate north, transecting western Russia, southern Finland, Estonia and Latvia, and central Sweden. In particular, the age and isotopic character of Suwałki are not unlike those of the well-studied Salmi rapakivi granite-anorthosite batholith in western Russia (Karelia). Received: 4 December 1998 / Accepted: 11 November 1999  相似文献   

A polyphase glacitectonic model for ice-marginal retreat and terminal moraine development: the Middle Pleistocene British Ice Sheet,northern Norfolk,UK     

Jonathan R. Lee  Emrys Phillips  Stephen J. Booth  James Rose  Hannah M. Jordan  Steven M. Pawley  Martin Warren  Russell S. Lawley 《Proceedings of the Geologists' Association. Geologists' Association》2013

Recent investigations from modern environments demonstrate that many terminal moraines do not simply record a single glacial maximum, but instead reveal a complex oscillatory pattern of ice-marginal behaviour including polyphase retreat. Within this study, we examine the geomorphology, geology and internal structure of a terminal moraine complex – the ‘Cromer Ridge’ in north Norfolk to reconstruct patterns of ice-marginal behaviour. Previously, this landform was interpreted as the limit of a southern extension of the British Ice Sheet during a Middle Pleistocene glaciation. Evidence presented here reveals a more complicated pattern of ice-marginal behaviour with the ‘Cromer Ridge’ reinterpreted as a ‘complex’ comprising several ridge elements. We propose that the maximum ice extent lay further to the south, with the size and morphology of the largest ridge element (the ‘Cromer Ridge’ as previously defined) a facet of thrust-stacking at an ice-marginal still-stand. We recognise multiple oscillations of the ice-front recorded against a twelve-stage model for the decay of the southern margins of a fast-flowing lobe of North Sea ice. Changes in ice-marginal dynamics are identified by the superimposition and lateral and vertical evolution of glacitectonic styles. Differences between these various states, and switches between ‘shallow’ and ‘deep’ thin-skinned glacitectonics, are strongly influenced by sub-marginal and proglacial water availability. Examination of the evidence for the morphostratigraphic proposals for the glacitectonic assemblage, within the context of the above interpretation, suggests that many of the ‘glacigenic landforms’ are erosional and a MIS 12 age of formation is favoured although several anomalies remain to be explained.  相似文献   

Local Perceptions of the Sustainability of Alaska’s Highly Contested Cook Inlet Salmon Fisheries     

Philip A. Loring  Hannah L. Harrison  S. Craig Gerlach 《社会与自然资源》2014,27(2):185-199

Using a mixed set of ethnographic methods including interviews and a structured survey, we evaluate local perceptions about the sustainability of salmon fisheries among fishers of the Cook Inlet region of Alaska. A majority of residents report participating in these fisheries, but we find significant disagreement about their sustainability. Household income and the types of fishing practiced both influence people's responses, and many implicated specific user groups for overharvesting and/or for receiving unfair catch allocations. Drawing on the theoretical areas of information theory and political ecology, we argue that these findings reveal a complex interplay among the practical, social, and political aspects of how local resource users, or “local experts,” develop and communicate their assessments of ecological conditions in a context of conflict. We conclude with notes on future research as it relates to the successful design of local-management and co-management solutions, especially in settings where resources are contested by stakeholders.  相似文献   

Review of the source characteristics of the Great Sumatra–Andaman Islands earthquake of 2004     

William Menke  Hannah Abend  Dalia Bach  Kori Newman  Vadim Levin 《Surveys in Geophysics》2006,27(6):603-613

The December 26, 2004 Sumatra–Andaman Island earthquake, which ruptured the Sunda Trench subduction zone, is one of the three largest earthquakes to occur since global monitoring began in the 1890s. Its seismic moment was M ₀ = 1.00 × 10²³–1.15 × 10²³ Nm, corresponding to a moment-magnitude of M _w = 9.3. The rupture propagated from south to north, with the southerly part of fault rupturing at a speed of 2.8 km/s. Rupture propagation appears to have slowed in the northern section, possibly to ∼2.1 km/s, although published estimates have considerable scatter. The average slip is ∼5 m along a shallowly dipping (8°), N31°W striking thrust fault. The majority of slip and moment release appears to have been concentrated in the southern part of the rupture zone, where slip locally exceeded 30 m. Stress loading from this earthquake caused the section of the plate boundary immediately to the south to rupture in a second, somewhat smaller earthquake. This second earthquake occurred on March 28, 2005 and had a moment-magnitude of M _w = 8.5.  相似文献   

Nuances of neighbourhood: Children’s perceptions of the space between home and school in Auckland, New Zealand     

Hannah Mitchell  Damian C.A. Collins 《Geoforum》2007,38(4):614-627

This paper examines primary school children’s experiences of travelling between home and school within three neighbourhoods. Our investigation is set in Auckland, New Zealand, where parental practices such as chauffeuring are commonplace, yet are increasingly recognised as limiting children’s physical fitness and environmental awareness. Drawing on children’s voices, writing and photographs, we investigate how children currently travel to school, how they would like to travel, and how their perspectives on neighbourhood space vary by age, socio-economic status and school location. Findings reveal that over half of the participants did not like the way they travelled to school. Most desire to travel independently within public space, but are limited in their ability to do so, given the fears and obstacles that prevail within their neighbourhoods. We contend that restricted use of public space diminishes children’s agency in inner suburbs. Our analysis reveals that children favour ‘active travel’ for many of the same reasons as health professionals and transport planners. We conclude that as long as children are seen as innocents in need of protection, they will have limited agency in travel decisions and highly contingent access to public space.  相似文献   

NIMBY localism and national inequitable exclusion alliances: The case of syringe exchange programs in the United States     

Barbara Tempalski  Risa Friedman  Marie Keem  Hannah Cooper  Samuel R. Friedman   《Geoforum》2007,38(6):1250-1263

Syringe exchange programs (SEPs) aim to reduce the harm associated with injection drug use (IDU). Although they have been accepted as critical components of HIV prevention in many parts of the world, they are often unwelcome and difficult to set up and maintain, even in communities hardest hit by IDU-related HIV transmission. This research examines socio-cultural and political processes that shape community and institutional resistance toward establishing and maintaining SEPs. These processes are configured and reinforced through the socio-spatial stigmatizing of IDUs, and legal and public policy against SEPs. Overarching themes the paper considers are: (1) institutional and/or political opposition based on (a) political and law enforcement issues associated with state drug paraphernalia laws and local syringe laws; (b) harassment of drug users and resistance to services for drug users by local politicians and police; and (c) state and local government (in)action or opposition; and (2) the stigmatization of drug users and location of SEPs in local neighborhoods and business districts. Rather than be explained by “not in my back yard” localism, this pattern seems best conceptualized as an “inequitable exclusion alliance” (IEA) that institutionalizes national and local stigmatizing of drug users and other vulnerable populations.  相似文献   

Origin of silicic volcanic rocks in Central Costa Rica: a study of a chemically variable ash-flow sheet in the Tiribí Tuff     

Rachel S. Hannah  Thomas A. Vogel  Lina C. Patino  Guillermo E. Alvarado  Wendy Pérez  Diane R. Smith 《Bulletin of Volcanology》2002,64(2):117-133

Chemical heterogeneities of pumice clasts in an ash-flow sheet can be used to determine processes that occur in the magma chamber because they represent samples of magma that were erupted at the same time. The dominant ash-flow sheet in the Tiribí Tuff contains pumice clasts that range in composition from 55.1 to 69.2 wt% SiO₂. It covers about 820 km² and has a volume of about 25 km³ dense-rock equivalent (DRE). Based on pumice clast compositions, the sheet can be divided into three distinct chemical groupings: a low-silica group (55.1-65.6 wt% SiO₂), a silicic group (66.2-69.2 wt% SiO₂), and a mingled group (58.6-67.7 wt% SiO₂; all compositions calculated 100% anhydrous). Major and trace element modeling indicates that the low-silica magma represents a mantle melt that has undergone fractional crystallization, creating a continuous range of silica content from 55.1-65.6 wt% SiO₂. Eu/Eu*, MREE, and HREE differences between the two groups are not consistent with crystal fractionation of the low-silica magma to produce the silicic magma. The low-silica group and the silicic group represent two distinct magmas, which did not evolve in the same magma chamber. We suggest that the silicic melts resulted from partial melting of relatively hot, evolved calc-alkaline rocks that were previously emplaced and ponded at the base of an over-thickened basaltic crust. The mingled group represents mingling of the two magmas shortly before eruption. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00445-001-0188-8.  相似文献