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321.
Serena Caplins Miguel Angel Penna-Diaz Erick Godoy Nelson Valdivia J. M. Turbeville Martin Thiel 《Marine Biology》2012,159(6):1363-1374
Understanding the impact of environmental stressors on predator activity is a prerequisite to understanding the underlying
mechanisms shaping community structure. The nemertean Prosorhochmus nelsoni is a common predator in the mid-intertidal zone on rocky shores along the Chilean coast, where it can reach very high abundances
(up to 260 ind m−2) in algal turfs, algal crusts, barnacle crusts, and mixed substrata. Tidal and diurnal scans revealed that the activity of
P. nelsoni is primarily restricted to night and early-morning low tides and is relatively low when air temperatures are high. On average,
larger worms crawled faster than smaller worms, with their maximum velocity being influenced by substratum type. Their estimated
rate of predation is 0.092 prey items nemertean−1 day−1, just below the laboratory rate of ~0.2 amphipods nemertean−1 day−1 previously estimated for this species. P. nelsoni consumes a diverse spectrum of prey items (i.e., amphipods, isopods, decapods, barnacles, and dipterans) and is possibly
exerting a significant influence on its prey populations. We suggest that the opportunistic predatory behavior of this intertidal
predator is caused by the trade-off between immediate persistence (e.g., avoidance of desiccation) and long-term survival
through successful foraging. 相似文献
322.
Numerous studies have begun to tackle the social and cultural dimensions of perceiving and framing climate change. Scholars from geography and environmental psychology in particular have started to highlight the importance of so-called place-based approaches to studying regional and local framings of climate change. This paper stands in this tradition. It reports on findings derived from a nationwide survey of perceptions of and reactions to extreme weather events and interviews conducted with inhabitants of three islands in the coastal region of North Frisia (Germany). Coastal dwellers understand climate change through the lens of local and regional experiences of meteorological phenomena, seasonal changes, knowledge of the sea, and changes in local flora and fauna. Our detailed ecolinguistic analysis revealed six prevailing conceptual metaphors: Climate change is an enemy, preventing climate change is fight/war, climate change is punishment for human sins, climate change is overheating/heat, climate change is hot air/hoax and climate change is eco-dictatorship. These metaphors were used to make sense of climate change at the regional level and provide insights into place-based social and cultural conceptualisations of climate change. An understanding of these meanings should feed into developing more grounded climate change adaptation and mitigation strategies in coastal regions. 相似文献
323.
Claire M. Waluda Martin A. Collins Andrew D. Black Iain J. Staniland Philip N. Trathan 《Marine Biology》2010,157(1):99-112
Antarctic fur seals Arctocephalus gazella and macaroni penguins Eudyptes chrysolophus are the two main land-based krill Euphausia superba consumers in the northern Scotia Sea. Using a combination of concurrent at-sea (predator observations, net hauls and multi-frequency
acoustics), and land-based (animal tracking and diet analysis) techniques, we examined variability in the foraging ecology
of these sympatric top predators during the austral summer and autumn of 2004. Krill availability derived from acoustic surveys
was low during summer, increasing in autumn. During the breeding season, krill occurred in 80% of fur seal diet samples, with
fish remains in 37% of samples. Penguin diets contained the highest proportion of fish in over 20 years of routine monitoring
(46% by mass; particularly the myctophid Electrona antarctica), with krill (33%) and amphipods (Themisto gaudichaudii; 21%) also occurring. When constrained by the need to return and feed their offspring both predator species foraged to the
northwest of South Georgia, consistent with an area of high macrozooplankton biomass, but fur seals were apparently more successful
at exploiting krill. When unconstrained by chick-rearing (during March) penguins foraged close to the Shag Rocks shelf-break,
probably exploiting the high daytime biomass of fish in this area. Penguins and seals are able to respond differently to periods
of reduced krill abundance (in terms of variability in diet and foraging behaviour), without detriment to the breeding success
of either species. This highlights the importance of myctophid fish as an alternative trophic pathway for land-based predators
in the Scotia Sea ecosystem. 相似文献
324.
The spatial and temporal organization of ecological processes and features and the scales at which they occur are central topics to landscape ecology and metapopulation dynamics, and increasingly regarded as a cornerstone paradigm for understanding ecological processes. Hence, there is need for computational approaches which allow the identification of the proper spatial or temporal scales of ecological processes and the explicit integration of that information in models. For that purpose, we propose a new method (multiscale codependence analysis, MCA) to test the statistical significance of the correlations between two variables at particular spatial or temporal scales. Validation of the method (using Monte Carlo simulations) included the study of type I error rate, under five statistical significance thresholds, and of type II error rate and statistical power. The method was found to be valid, in terms of type I error rate, and to have sufficient statistical power to be useful in practice. MCA has assumptions that are met in a wide range of circumstances. When applied to model the river habitat of juvenile Atlantic salmon, MCA revealed that variables describing substrate composition of the river bed were the most influential predictors of parr abundance at 0.4-4.1 km scales whereas mean channel depth was more influential at 200-300 m scales. When properly assessed, the spatial structuring observed in nature may be used purposefully to refine our understanding of natural processes and enhance model representativeness. 相似文献
325.
326.
We present how state-and-transition models (STMs) may be derived from image data, providing a graphical means of understanding how ecological dynamics are driven by complex interactions among ecosystem events. A temporal sequence of imagery of fine scale vegetation patterning was acquired from close range photogrammetry (CRP) of 1 m quadrats, in a long term monitoring project of Themeda triandra (Forsskal) grasslands in north western Australia. A principal components scaling of image metrics calculated on the imagery defined the state space of the STM, and thereby characterised the different patterns found in the imagery. Using the state space, we were able to relate key events (i.e. fire and rainfall) to both the image data and aboveground biomass, and identified distinct ecological ‘phases’ and ‘transitions’ of the system. The methodology objectively constructs a STM from imagery and, in principle, may be applied to any temporal sequence of imagery captured in any event-driven system. Our approach, by integrating image data, addresses the labour constraint limiting the extensive use of STMs in managing vegetation change in arid and semiarid rangelands. 相似文献
327.
Eichelter Johanna Wilhelm Harald Mautner Andreas Fahrngruber Barbara Schafler Erhard Eder Andreas Kozich Martin Bismarck Alexander 《Journal of Polymers and the Environment》2021,29(11):3509-3524
Journal of Polymers and the Environment - We evaluated the influence of blending various renewable polymer grades and amounts to allow for high stretchability during stretching at 800 mm/s... 相似文献
328.
Jiri Serafin Ales Bebcak Ales Bernatik Petr Lepik Miroslav Mynarz Martin Pitt 《Journal of Loss Prevention in the Process Industries》2013,26(1):209-214
A standard spherical apparatus for measuring explosion characteristics was modified to give increased and controlled turbulence within a dust–air mixture. This was intended to mimic the local effects which may occur during industrial dust explosions, particularly secondary ones which may develop in ducts or mine galleries where the initial explosion causes an increased air velocity and suspension of further quantities of dust.The results show that there may be a doubling of the maximum explosion pressure and of the rate of pressure rise during the explosion under more turbulent conditions. This is significant for modelling of dust explosions and suggests that explosion relief may be inadequate if this factor is not taken into consideration.The modified apparatus therefore gives a laboratory method for assessing the effect of turbulence in dust explosions. 相似文献
329.
Recent concerns surrounding the growth of mobility and associated increases in journey length and number of motorised journeys for an increasingly diverse pattern of trips have placed demands on the planning system in terms of the need to consider the land use-transport interaction. This paper first provides a review of relevant national planning policy in Scotland in particular. It then goes on to report findings from a recent survey which highlights the attitudes held by Scottish planning professionals to managing transport demand through land-use planning. The paper outlines the trade-offs encountered in practice between competing policy objectives. In Scotland there is no planning guidance equivalent to Planning Policy Guidance Note 13, which applies to England and Wales, around which there has been much debate on its impact on development control decisions and planning strategy. Draft guidance for Scotland was produced in 1996 for consultation and again in 1998, but at the time of writing has yet to be finalised. The findings from this study are timely in that they enable an assessment of the extent to which the planning system is being used to manage transport demand. Recent local government reorganisation in Scotland has resulted in significant changes to ways in which strategic planning and development control policy are likely to proceed. The paper focuses on the extent to which local authority policy emphasises the need to reduce travel through planning. 相似文献
330.
J. Philip Burkhalter Timothy C. Martin Richard G. Allen Jeppe Kjaersgaard Erin Wilson Ray Alvarado Jason S. Polly 《Journal of the American Water Resources Association》2013,49(3):498-517
We compared two methods of estimating crop water consumption to assess whether remote sensing techniques provide consumptive use (CU) estimates commensurate with conventional methods. Using available historical satellite and meteorological data, we applied Mapping EvapoTranspiration at high Resolution using Internalized Calibration (METRIC) to 317,455 ha in the South Platte basin, in northeastern Colorado, for the 2001 irrigation season. We then compared these derived CU estimates with values calculated by using the Colorado Water Conservation Board's South Platte Decision Support System StateCU model. Evaluating the data by irrigation ditch service area, we disaggregated the output to allow for comparison by service area size, crop type, irrigation method, water supply source, and water availability. We concluded that METRIC is a suitable alternative to StateCU in the South Platte basin and could help to identify areas with inhibited crop growth or deficit irrigation practices. In addition, METRIC could be used as a complement to StateCU to refine StateCU model parameters, allowing for more accurate estimates of crop water shortages and groundwater recharge associated with irrigation delivery and application. 相似文献