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61.
62.
During R.R.S. Discovery Cruise 100 in the Southern Ocean (1979), 620 specimens of the Antarctic cranchiid squid Galiteuthis glacialis (Chun) were caught in the RMT8 opening-closing net, to the south of the Antarctic Polar Front (APF). The catch was dominated by individuals <20 mm dorsal mantle length (DML) and, apart from two specimens, the rest of the catch was <60 mm DML. Two larger squid (255 mm DML) were both immature and apparently female. The species is concentrated at a depth of 300 to 400 m; there is evidence of ontogenetic spreading and a shift in the modal depth of the population from the 300 to 400 m horizon in daylight to the 200 to 300 m horizon in darkness. The collection confirms the circumpolar distribution of the species and supports previous evidence that it rarely, if ever, occurs to the north of the APF. As in Mesonychoteuthis hamiltoni, the only other species of cranchiid squid known to occur south of the APF, the early-life phase of G. glacialis is concentrated in the upper zone of the warm deep water beneath the Antarctic surface layer where, putatively, there is a zone of enhanced biological activity. 相似文献
63.
Esther Clarke Ulrich H. Reichard Klaus Zuberbühler 《Behavioral ecology and sociobiology》2012,66(1):85-96
Predation on gibbons is rarely observed in the wild. However, the gibbons' moderate body size and relatively small social
groups suggest high vulnerability to predation. To assess the role of predation and to study their anti-predator behaviour,
we presented visual predator models to nine groups of wild white-handed gibbons at Khao Yai National Park, Thailand. We measured
subjects' immediate and delayed responses to four potential predators: tiger, clouded leopard, crested serpent eagle and reticulated
python. Subjects reliably approached all four predators. In response to tigers and leopards, they additionally produced predator-specific
songs and defecated copiously. In terms of delayed responses, distance between mated adults decreased, but only after exposure
to the tiger model. In response to eagles and pythons, gibbons consistently vocalised, but this did not always include predator
singing, and we found no long-term effects in overall activity or strata use. However, during 6 of 26 predator encounters,
the gibbons produced songs with a structure that was intermediate between a duet song and a predator song more than 20 min
after the predator encounter, indicating a long-term effect on their vocal behaviour. This study demonstrates that gibbons
discriminate between different potential predators and respond to them with adaptive anti-predator behaviour, which include
predator-specific vocal responses. We conclude that gibbons are not immune to predation and that terrestrial predators elicit
consistent immediate and delayed anti-predation responses. 相似文献
64.
The atomised nature of the humanitarian system has led to frequent and repeated attempts to coordinate humanitarian activity. Since 2005, some of the best resourced, and arguably most successful, coordination mechanisms have been the humanitarian Clusters, groups of UN (United Nations) and non‐UN actors that engage in sectoral coordination of humanitarian response (such as the provision of healthcare and water) at the global and country level. Nevertheless, it is not clear exactly what ‘coordination’ means in the context of a Cluster. Formal guidance suggests that they should be aiming to create a single, joint strategy to guide the activities of members. Actual experience of the Clusters, however, indicates that looser forms of coordination are more effective. This finding resonates with organisational theory, and with the experience of emergency management professionals beyond the international humanitarian sector. To capitalise fully on the success of the Clusters, policymakers may need to rethink their attitudes to, and expectations of, coordination. 相似文献
65.
Dune slack habitats are highly dependent on the availability of water to support flora and fauna. Typically this is provided
by shallow groundwater. This paper describes the seasonal and long term variation in groundwater levels in part of the Sefton
coastline between 1972 and 2007. The effects of climate change, vegetation management and coastline realignment on groundwater
levels are modelled. The observed annual water table levels rise and fall with an amplitude of 1.5 m, but longer term variations
and trends are apparent. A stochastic water balance model was used to describe the changes in water table levels in slack
floors in the open dunes and also in areas afforested with pine trees. It was found that the pine trees evaporated 214 mm/year
more than open dunes vegetation, resulting in the water table being 0.5–1.0 m lower under the trees than under the open dunes.
The effects of climate change on the ground water was simulated using predictions of future climate conditions based on the
UKCIP02 medium high emissions scenario. The increase in temperature and change in rainfall patterns will result in a decrease
in mean ground water levels by 1.0–1.5 mm in the next 90 years. Typical patterns consist of sequences of 5–10 years of low
water table levels interspersed by infrequent sequences consisting of 2–5 years of relatively high or “normal” levels. These
results indicate that that flora and fauna that cannot survive a 5–10 year period of water table levels >2.5 m below ground
level are unlikely to survive or persist in many slack areas and a change in the ecology of these slack may become inevitable.
Other effects of climate change include sea level rise which will result in a gradual rise in water table levels. Coastal
erosion will increase the water table gradient to the sea and result in a slight lowering of the ground water levels. Conversely
coastal accretion will reverse this process. The spatial distribution of coastal erosion and accretion along the Sefton coastline
and its likely impacts on groundwater levels are discussed. The modelling work described in this paper has identified the
factors which have the largest effect on groundwater levels in temperate coastal dune systems. 相似文献
66.
67.
Joseph H. Rustick David S. Kosson Steven L. Krahn Michael T. Ryan Craig H. Benson James H. Clarke 《补救:环境净化治理成本、技术与工艺杂志》2015,26(1):69-91
Near surface disposal facility design and management are examined and compared using a systems approach that defines facility performance as a function of three components (or subsystems): the disposal facility design (cover systems and bottom liners); the properties of the waste (waste composition, waste form and waste package); and the site‐specific environmental features (climate, geology, and hydrology). We report an evaluation of five DOE near surface disposal facility case studies, selected to provide a “representative” sample that included disposal sites with a range of waste and environmental characteristics across the DOE. The facilities selected were the Savannah River E‐Area Engineered Trenches, Hanford Integrated Disposal Facility, Idaho Radioactive Waste Management Complex, Oak Ridge Environmental Management Waste Management Facility, and Nevada National Security Site Area 5. ©2015 Wiley Periodicals, Inc. 相似文献
68.
The formation and fate of chlorinated organic substances in temperate and boreal forest soils 总被引:1,自引:0,他引:1
Nicholas Clarke Květoslava Fuksová Milan Gryndler Zora Lachmanová Hans-Holger Liste Jana Rohlenová Reiner Schroll Peter Schröder Miroslav Matucha 《Environmental science and pollution research international》2009,16(2):127-143
Background, aim and scope Chlorine is an abundant element, commonly occurring in nature either as chloride ions or as chlorinated organic compounds
(OCls). Chlorinated organic substances were long considered purely anthropogenic products; however, they are, in addition,
a commonly occurring and important part of natural ecosystems. Formation of OCls may affect the degradation of soil organic
matter (SOM) and thus the carbon cycle with implications for the ability of forest soils to sequester carbon, whilst the occurrence
of potentially toxic OCls in groundwater aquifers is of concern with regard to water quality. It is thus important to understand
the biogeochemical cycle of chlorine, both inorganic and organic, to get information about the relevant processes in the forest
ecosystem and the effects on these from human activities, including forestry practices. A survey is given of processes in
the soil of temperate and boreal forests, predominantly in Europe, including the participation of chlorine, and gaps in knowledge
and the need for further work are discussed.
Results Chlorine is present as chloride ion and/or OCls in all compartments of temperate and boreal forest ecosystems. It contributes
to the degradation of SOM, thus also affecting carbon sequestration in the forest soil. The most important source of chloride
to coastal forest ecosystems is sea salt deposition, and volcanoes and coal burning can also be important sources. Locally,
de-icing salt can be an important chloride input near major roads. In addition, anthropogenic sources of OCls are manifold.
However, results also indicate the formation of chlorinated organics by microorganisms as an important source, together with
natural abiotic formation. In fact, the soil pool of OCls seems to be a result of the balance between chlorination and degradation
processes. Ecologically, organochlorines may function as antibiotics, signal substances and energy equivalents, in descending
order of significance. Forest management practices can affect the chlorine cycle, although little is at present known about
how.
Discussion The present data on the apparently considerable size of the pool of OCls indicate its importance for the functioning of the
forest soil system and its stability, but factors controlling their formation, degradation and transport are not clearly understood.
It would be useful to estimate the significance and rates of key processes to be able to judge the importance of OCls in SOM
and litter degradation. Effects of forest management processes affecting SOM and chloride deposition are likely to affect
OCls as well. Further standardisation and harmonisation of sampling and analytical procedures is necessary.
Conclusions and perspectives More work is necessary in order to understand and, if necessary, develop strategies for mitigating the environmental impact
of OCls in temperate and boreal forest soils. This includes both intensified research, especially to understand the key processes
of formation and degradation of chlorinated compounds, and monitoring of the substances in question in forest ecosystems.
It is also important to understand the effect of various forest management techniques on OCls, as management can be used to
produce desired effects. 相似文献
69.
The upper critical thermal limits were measured as heat-coma temperatures in Littorina species as a tool for examining physiological diversity. Thermal tolerance was found to be stable within a population, but
extensive variation occurred between populations and species. All species examined displayed heat-coma values of ∼30 °C and
did not show a positive correlation with shore height. Eulittoral-fringe species tended to have higher coma temperatures than
eulittoral species. Coma temperatures varied both seasonally and geographically. Lethal thermal limits were also investigated;
these were ∼10 C° higher than coma temperatures.
Received: 16 August 1999 / Accepted: 13 June 2000 相似文献
70.
James M. Omernik David P. Larsen Christina M. Rohm Sharon E. Clarke 《Environmental management》1988,12(6):815-825
A map of summer total phosphorus in lakes has been compiled for Minnesota, Wisconsin, and Michigan to clarify regional patterns in attainable lake trophic state. Total phosphorus was used as a measure of lake trophic state because: (1) phosphorus plays a central role in controlling the overall fertility of most lakes, (2) total phosphorus values are available for a great number of lakes, and (3) phosphorus is measured in a consistent manner. The maps were compiled using patterns of total phosphorus data and observed associations between these data and geographic characteristics including physiography, land use, geology, and soils. Regions depicted on the map represent areas of similarity in phosphorus concentrations in lakes, or similarity in the mosaic of values, as compared to adjacent areas. Within each region, differences in total phosphorus can be compared to natural and anthropogenic factors to determine the types of lakes representative of each region, the factors associated with differences in quality, and the realistically attainable phosphorus levels for each type of lake. 相似文献