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181.
William V. Sweet Jens W. Geratz 《Journal of the American Water Resources Association》2003,39(4):861-871
ABSTRACT: Bank full hydraulic geometry relationships relate stream channel geometry to watershed size for specific physiographic regions. This paper presents bank full hydraulic geometry relationships and recurrence intervals for the Southeastern Plain coercion and the flat woods subtype of the Middle Atlantic Coastal Plain ecoregion found within North Carolina's Coastal Plain physiographic province. Cross‐sectional and longitudinal survey data from gated and unpaged streams were used to compute channel dimension and profile information. Power functions were developed, relating drainage area to bank full discharge, cross‐sectional area, width, and mean depth. Recurrence intervals of bank full events were estimated from gagged streams using both a Log‐Pearson Type III distribution of peak annual discharge and a partial‐duration series of average daily discharge. Results from both methods indicate that average bank full recurrence intervals for the study area are below one year. Determinations of recurrence intervals by the Log‐Pearson Type III distribution were for the most part inconclusive (less than one year), while a partial duration series estimated a 0.19 year average, ranging from 0.11 to 0.31 years. 相似文献
182.
Bjørn Kløve Pertti Ala-aho Guillaume Bertrand Zuzana Boukalova Ali Ertürk Nico Goldscheider Jari Ilmonen Nusret Karakaya Hans Kupfersberger Jens Kvœrner Angela Lundberg Marta Mileusni? Agnieszka Moszczynska Timo Muotka Elena Preda Pekka Rossi Dmytro Siergieiev Josef Šimek Przemys?aw Wachniew Vadineanu Angheluta Anders Widerlund 《Environmental Science & Policy》2011,14(7):770-781
Groundwater dependent ecosystems (GDEs) include valuable ecosystems such as springs, wetlands, rivers, lakes and lagoons. The protection of these systems and services they provide is highlighted by international agreements, i.e. Ramsar convention on wetlands, and regional legislation, i.e. the European Water Framework Directive. Groundwater provides water, nutrients and a relatively stable temperature. However, the role of groundwater in surface ecosystems is not fully understood. The ecosystem can depend on groundwater directly or indirectly, and the reliance can be continuous, seasonal or occasional. This has implications for the vulnerability of ecosystems, as some may be easily affected by external pressure. Conceptual models and quantitative assessments of how groundwater interacts with the environment are needed. GDEs are also threatened by different land use activities and climate change. Hence, we need to understand how GDEs are affected by changes in groundwater quantity and quality, as severe groundwater changes have been observed in many regions. This study examines key aspects of GDEs (hydrogeology, geochemistry and biodiversity) in order to improve conceptual understanding of the role of groundwater in such ecosystems. The status and baseline of different types of GDEs are discussed, with particular emphasis on past evidence of environmental change and potential thresholds and threats in GDEs in various parts of Europe with different land use, climate and geology. 相似文献
183.
Groundwater dependent ecosystems. Part II. Ecosystem services and management in Europe under risk of climate change and land use intensification 总被引:1,自引:0,他引:1
Bjørn Kløve Andrew Allan Guillaume Bertrand Elzbieta Druzynska Ali Ertürk Nico Goldscheider Sarah Henry Nusret Karakaya Timo P. Karjalainen Phoebe Koundouri Hans Kupfersberger Jens Kvœrner Angela Lundberg Timo Muotka Elena Preda Manuel Pulido-Velazquez Peter Schipper 《Environmental Science & Policy》2011,14(7):782-793
Groundwater in sufficient amounts and of suitable quality is essential for potable water supplies, crop irrigation and healthy habitats for plant and animal biocenoses. The groundwater resource is currently under severe pressure from land use and pollution and there is evidence of dramatic changes in aquifer resources in Europe and elsewhere, despite numerous policy measures on sustainable use and protection of groundwater. Little is known about how such changes affect groundwater dependent ecosystems (GDEs), which include various aquatic and terrestrial ecosystems above ground and inside the aquifer. Future management must take this uncertainty into account. This paper focuses on multiple aspects of groundwater science, policy and sustainable management. Examples of current management methods and practices are presented for selected aquifers in Europe and an assessment is made of the effectiveness of existing policies such as the European Water Framework Directive and the Habitat Directive in practice and of how groundwaters and GDEs are managed in various conditions. The paper highlights a number of issues that should be considered in an integrated and holistic approach to future management of groundwater and its dependent ecosystems. 相似文献
184.
Bacterial antibiotic resistance levels in Danish farmland as a result of treatment with pig manure slurry 总被引:17,自引:0,他引:17
Sengeløv G Agersø Y Halling-Sørensen B Baloda SB Andersen JS Jensen LB 《Environment international》2003,28(7):587-595
Resistance to tetracycline, macrolides and streptomycin was measured for a period of 8 months in soil bacteria obtained from farmland treated with pig manure slurry. This was done by spread plating bacteria on selective media (Luria Bertani (LB) medium supplemented with antibiotics). To account for seasonal variations in numbers of soil bacteria, ratios of resistant bacteria divided by total count on nonselective plates were calculated. Soil samples were collected from four different farms and from a control soil on a fifth farm. The control soil was not amended with animal manure. The occurrence of tetracycline-resistant bacteria was elevated after spread of pig manure slurry but declined throughout the sampling period to a level corresponding to the control soil. Higher load of pig manure slurry yielded higher occurrence of tetracycline resistance after spreading; however, the tetracycline resistance declined to normal occurrence defined by the tetracycline resistance occurrence in the control soil. Concentrations of tetracycline in soil and in pig manure slurry were measured using HPLC. No tetracycline exceeding the detection limit was found in soil samples. Manure slurry concentrations of tetracycline for three of the farms were 42, 81 and 698 microg/l, respectively. For streptomycin and macrolides, only minor variations in resistance levels were detected. Results obtained in this study thus indicate that tetracycline resistance levels in soil are temporarily influenced by the addition of pig manure slurry. The results indicate also that increased amount of pig manure slurry amendment may result in increased levels of tetracycline resistance in the soil. 相似文献
185.
Darren P. Croft Jens Krause Safi K. Darden Indar W. Ramnarine Jolyon J. Faria Richard James 《Behavioral ecology and sociobiology》2009,63(10):1495-1503
The social fine structure of a population plays a central role in ecological and evolutionary processes. Whilst many studies
have investigated how morphological traits such as size affect social structure of populations, comparatively little is known
about the influence of behaviours such as boldness and shyness. Using information on social interactions in a wild population
of Trinidadian guppies (Poecilia reticulata), we construct a social network. For each individual in the network, we quantify its behavioural phenotype using two measures
of boldness, predator inspection tendency, a repeatable and reliably measured behaviour well studied in the context of co-operation,
and shoaling tendency. We observe striking heterogeneity in contact patterns, with strong ties being positively assorted and
weak ties negatively assorted by our measured behavioural traits. Moreover, shy fish had more network connections than bold
fish and these were on average stronger. In other words, social fine structure is strongly influenced by behavioural trait.
We assert that such structure will have implications for the outcome of selection on behavioural traits and we speculate that
the observed positive assortment may act as an amplifier of selection contributing to the maintenance of co-operation during
predator inspection. 相似文献
186.
The confusion effect describes the observed decrease in the likelihood that a predator will successfully catch any prey when
attacking larger groups of moving prey. We introduce readers to the work of cognitive psychologists interested in human visual
attention who have been studying their own version of the confusion effect for many years, developing methods and concepts
that may be of fundamental utility to behavioral ecologists. In psychology, ‘basic features’ are characteristics unique to
a target object in the visual field that no distracter objects share. Images containing targets with basic features are often
less likely to induce the confusion effect in human subjects. Target objects with conjunctions of features, on the other hand,
have no individual characteristics unique from distracters, but unique characteristics in combination. Such targets more often induce the confusion effect in humans. We propose the ‘basic feature’ (vs. conjunctions of features)
as a new organizing concept for studies on the occurrence of the confusion effect in nature, potentially allowing predictions
about which types of prey groups are likely to induce the confusion effect in predators. 相似文献
187.
188.
Jesper H. Andersen Henrik Fossing Jens W. Hansen Ole H. Manscher Ciarán Murray Ditte L. J. Petersen 《Ambio》2014,43(7):906-913
Nutrient enrichment of coastal marine waters caused by losses of nitrate (NO3−) from agriculture is an increasing global problem. In the European Union, the Nitrates Directive (ND) of 1991 was meant to be a cornerstone in reducing eutrophication effects in coastal waters downstream from intensively farmed catchments. Although reductions in losses of nitrate have been attained, very few Member States have yet been able to reduce eutrophication effects caused by inputs of NO3− from agriculture. We report trends in concentrations of NO3− and chlorophyll-a (Chl-a) in Danish coastal and open marine waters during the period from 1996 to 2011 together with an assessment of eutrophication status based on multiple indicators (e.g. nutrient concentrations, Chl-a, submerged aquatic vegetation and benthic macroinvertebrates). Despite decreasing concentrations of both NO3−and Chl-a, Danish coastal waters are not yet to be classified as ‘unaffected by eutrophication’. In order to improve future pan-European evaluations of the effectiveness of the ND, we argue for the added value of including indicators and assessment principles from other European Directives, i.e. the Water Framework Directive and the Marine Strategy Framework Directive.
Electronic supplementary material
The online version of this article (doi:10.1007/s13280-014-0514-y) contains supplementary material, which is available to authorized users. 相似文献189.
Tarmo Soomere Kristofer Döös Andreas Lehmann H. E. Markus Meier Jens Murawski Kai Myrberg Emil Stanev 《Ambio》2014,43(1):94-104
The ever increasing impact of the marine industry and transport on vulnerable sea areas puts the marine environment under exceptional pressure and calls for inspired methods for mitigating the impact of the related risks. We describe a method for preventive reduction of remote environmental risks caused by the shipping and maritime industry that are transported by surface currents and wind impact to the coasts. This method is based on characterizing systematically the damaging potential of the offshore areas in terms of potential transport to vulnerable regions of an oil spill or other pollution that has occurred in a particular area. The resulting maps of probabilities of pollution to be transported to the nearshore and the time it takes for the pollution to reach the nearshore are used to design environmentally optimized fairways for the Gulf of Finland, Baltic Proper, and south-western Baltic Sea. 相似文献
190.
Environmental governance and management are facing a multiplicity of challenges related to spatial scales and multiple levels
of governance. Water management is a field particularly sensitive to issues of scale because the hydrological system with
its different scalar levels from small catchments to large river basins plays such a prominent role. It thus exemplifies fundamental
issues and dilemmas of scale in modern environmental management and governance. In this introductory article to an Environmental Management special feature on “Multilevel Water Governance: Coping with Problems of Scale,” we delineate our understanding of problems
of scale and the dimensions of scalar politics that are central to water resource management. We provide an overview of the
contributions to this special feature, concluding with a discussion of how scalar research can usefully challenge conventional
wisdom on water resource management. We hope that this discussion of water governance stimulates a broader debate and inquiry
relating to the scalar dimensions of environmental governance and management in general. 相似文献