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81.
Steven?J.?CookeEmail authorView authors OrcID profile Eduardo?G.?Martins Daniel?P.?Struthers Lee?F.?G.?Gutowsky Michael?Power Susan?E.?Doka John?M.?Dettmers David?A.?Crook Martyn?C.?Lucas Christopher?M.?Holbrook Charles?C.?Krueger 《Environmental monitoring and assessment》2016,188(4):239
Freshwater fish move vertically and horizontally through the aquatic landscape for a variety of reasons, such as to find and exploit patchy resources or to locate essential habitats (e.g., for spawning). Inherent challenges exist with the assessment of fish populations because they are moving targets. We submit that quantifying and describing the spatial ecology of fish and their habitat is an important component of freshwater fishery assessment and management. With a growing number of tools available for studying the spatial ecology of fishes (e.g., telemetry, population genetics, hydroacoustics, otolith microchemistry, stable isotope analysis), new knowledge can now be generated and incorporated into biological assessment and fishery management. For example, knowing when, where, and how to deploy assessment gears is essential to inform, refine, or calibrate assessment protocols. Such information is also useful for quantifying or avoiding bycatch of imperiled species. Knowledge of habitat connectivity and usage can identify critically important migration corridors and habitats and can be used to improve our understanding of variables that influence spatial structuring of fish populations. Similarly, demographic processes are partly driven by the behavior of fish and mediated by environmental drivers. Information on these processes is critical to the development and application of realistic population dynamics models. Collectively, biological assessment, when informed by knowledge of spatial ecology, can provide managers with the ability to understand how and when fish and their habitats may be exposed to different threats. Naturally, this knowledge helps to better evaluate or develop strategies to protect the long-term viability of fishery production. Failure to understand the spatial ecology of fishes and to incorporate spatiotemporal data can bias population assessments and forecasts and potentially lead to ineffective or counterproductive management actions. 相似文献
82.
83.
Lars Brabyn Peyman Zawar-Reza Glen Stichbury Craig Cary Bryan Storey Daniel C. Laughlin Marwan Katurji 《Environmental monitoring and assessment》2014,186(4):2619-2628
The McMurdo Dry Valleys of Antarctica are the largest snow/ice-free regions on this vast continent, comprising 1 % of the land mass. Due to harsh environmental conditions, the valleys are bereft of any vegetation. Land surface temperature is a key determinate of microclimate and a driver for sensible and latent heat fluxes of the surface. The Dry Valleys have been the focus of ecological studies as they arguably provide the simplest trophic structure suitable for modelling. In this paper, we employ a validation method for land surface temperatures obtained from Landsat 7 ETM + imagery and compared with in situ land surface temperature data collected from four transects totalling 45 iButtons. A single meteorological station was used to obtain a better understanding of daily and seasonal cycles in land surface temperatures. Results show a good agreement between the iButton and the Landsat 7 ETM + product for clear sky cases. We conclude that Landsat 7 ETM + derived land surface temperatures can be used at broad spatial scales for ecological and meteorological research. 相似文献
84.
Loïc D’Orangeville Daniel Houle Benoît Côté Louis Duchesne 《Environmental monitoring and assessment》2014,186(12):8191-8202
The projected increase in atmospheric N deposition and air/soil temperature will likely affect soil nutrient dynamics in boreal ecosystems. The potential effects of these changes on soil ion fluxes were studied in a mature balsam fir stand (Abies balsamea [L.] Mill) in Quebec, Canada that was subjected to 3 years of experimentally increased soil temperature (+4 °C) and increased inorganic N concentration in artificial precipitation (three times the current N concentrations using NH4NO3). Soil element fluxes (NO3, NH4, PO4, K, Ca, Mg, SO4, Al, and Fe) in the organic and upper mineral horizons were monitored using buried ion-exchange membranes (PRS? probes). While N additions did not affect soil element fluxes, 3 years of soil warming increased the cumulative fluxes of K, Mg, and SO4 in the forest floor by 43, 44, and 79 %, respectively, and Mg, SO4, and Al in the mineral horizon by 29, 66, and 23 %, respectively. We attribute these changes to increased rates of soil organic matter decomposition. Significant interactions of the heating treatment with time were observed for most elements although no clear seasonal patterns emerged. The increase in soil K and Mg in heated plots resulted in a significant but small K increase in balsam fir foliage while no change was observed for Mg. A 6–15 % decrease in foliar Ca content with soil warming could be related to the increase in soil-available Al in heated plots, as Al can interfere with the root uptake of Ca. 相似文献
85.
86.
This study evaluates the effect of emission reductions at two coal-fired power plants in northwestern Colorado on a nearby wilderness area. Control equipment was installed at both plants during 1999–2004 to reduce SO2 and NOx emissions. One challenge was separating the effects of local from regional emissions, which also declined during the study period. The long-term datasets examined confirm that emission reductions had a beneficial effect on air and water quality in the wilderness. Despite a 75 % reduction in SO2 emissions, sulfate aerosols measured in the wilderness decreased by only 20 %. Because the site is relatively close to the power plants (<75 km), the slow rate of conversion of SO2 to sulfate, particularly under conditions of low relative humidity, might account for this less than one-to-one response. On the clearest days, emissions controls appeared to improve visibility by about 1 deciview, which is a small but perceptible improvement. On the haziest days, however, there was little improvement perhaps reflecting the dominance of regional haze and other components of visibility degradation particularly organic carbon and dust. Sulfate and acidity in atmospheric deposition decreased by 50 % near the southern end of the wilderness of which 60 % was attributed to power plant controls and the remainder to reductions in regional sources. Lake water sulfate responded rapidly to trends in deposition declining at 28 lakes monitored in and near the wilderness. Although no change in the acid–base status was observed, few of the lakes appear to be at risk from chronic or episodic acidification. 相似文献
87.
88.
Simulation of soil loss processes based on rainfall runoff and the time factor of governance in the Jialing River Watershed,China 总被引:1,自引:0,他引:1
Jialing River is the largest tributary in the catchment area of Three Gorges Reservoir, and it is also one of the important
areas of sediment yield in the upper reaches of the Yangtze River. In recent years, significant changes of water and sediment
characteristics have taken place. The "Long Control" Project implemented since 1989 had greatly changed the surface appearance
of the Jialing River Watershed (JRW), and it had made the environments of the watershed sediment yield and sediment transport
change significantly. In this research, the Revised Universal Soil Loss Equation was selected and used to predict the annual
average amount of soil erosion for the special water and sediment environments in the JRW after the implementation of the
"Long Control" Project, and then the rainfall–runoff modulus and the time factor of governance were both considered as dynamic
factors, the dynamic sediment transport model was built for soil erosion monitoring and forecasting based on the average sediment
yield model. According to the dynamic model, the spatial and temporal distribution of soil erosion amount and sediment transport
amount of the JRW from 1990 to 2007 was simulated using geographic information system (GIS) technology and space-grid algorithm.
Simulation results showed that the average relative error of sediment transport was less than 10% except for the extreme hydrological
year. The relationship between water and sediment from 1990 to 2007 showed that sediment interception effects of the soil
and water conservation projects were obvious: the annual average sediment discharge reduced from 145.3 to 35 million tons,
the decrement of sediment amount was about 111 million tons, and decreasing amplitude was 76%; the sediment concentration
was also decreased from 2.01 to 0.578 kg/m3. These data are of great significance for the prediction and estimation of the future changing trends of sediment storage
in the Three Gorges Reservoir and the particulate non-point source pollution load carried by sediment transport from watershed
surface. 相似文献
89.
Assessment of Spatiotemporal Varying Relationships Between Rainfall,Land Cover and Surface Water Area Using Geographically Weighted Regression 总被引:6,自引:0,他引:6
Stuart?BrownEmail author Vincent?L.?Versace Laurie?Laurenson Daniel?Ierodiaconou Jonathon?Fawcett Scott?Salzman 《Environmental Modeling and Assessment》2012,17(3):241-254
Traditional regression techniques such as ordinary least squares (OLS) are often unable to accurately model spatially varying
data and may ignore or hide local variations in model coefficients. A relatively new technique, geographically weighted regression
(GWR) has been shown to greatly improve model performance compared to OLS in terms of higher R
2 and lower corrected Akaike information criterion (AICC). GWR models have the potential to improve reliabilities of the identified relationships by reducing spatial autocorrelations
and by accounting for local variations and spatial non-stationarity between dependent and independent variables. In this study,
GWR was used to examine the relationship between land cover, rainfall and surface water habitat in 149 sub-catchments in a
predominately agricultural region covering 2.6 million ha in southeast Australia. The application of the GWR models revealed
that the relationships between land cover, rainfall and surface water habitat display significant spatial non-stationarity.
GWR showed improvements over analogous OLS models in terms of higher R
2 and lower AICC. The increased explanatory power of GWR was confirmed by the results of an approximate likelihood ratio test, which showed
statistically significant improvements over analogous OLS models. The models suggest that the amount of surface water area
in the landscape is related to anthropogenic drainage practices enhancing runoff to facilitate intensive agriculture and increased
plantation forestry. However, with some key variables not present in our analysis, the strength of this relationship could
not be qualified. GWR techniques have the potential to serve as a useful tool for environmental research and management across
a broad range of scales for the investigation of spatially varying relationships. 相似文献
90.
Hugo Ramiro Poma Verónica Beatriz Rajal María Dolores Blanco Fernández Patricia Angélica Barril Miguel Oscar Giordano Gisela Masachessi Laura Cecilia Martínez María Beatriz Isa María Cecilia Freire Gabriela López Riviello Daniel Cisterna Silvia Viviana Nates Viviana Andrea Mbayed 《Environmental monitoring and assessment》2013,185(3):2565-2576
Enteric viruses monitoring in surface waters requires the concentration of viruses before detection assays. The aim of this study was to evaluate different methods in terms of recovery efficiencies of bacteriophage PP7 of Pseudomonas aeruginosa, measured by real-time PCR, using it as a viral control process in water analysis. Different nucleic acid extraction methods (silica–guanidinium thiocyanate, a commercial kit (Qiagen Viral RNA Kit) and phenol–chloroform with alcohol precipitation) exhibited very low recovery efficiencies (0.08–4.18 %), being the most efficient the commercial kit used for subsequent experiments. To evaluate the efficiency of three concentration methods, PBS (as model for clean water) and water samples from rivers were seeded to reach high (HC, 106 pfu ml?1) and low concentrations (LC, 104 pfu ml?1) of PP7. Tangential ultrafiltration proved to be more efficient (50.36?±?12.91, 17.21?±?9.22 and 12.58?±?2.35 % for HC in PBS and two river samples, respectively) than adsorption–elution with negatively charged membranes (1.00?±?1.34, 2.79?±?2.62 and 0.05?±?0.08 % for HC in PBS and two river samples, respectively) and polyethylene glycol precipitation (15.95?±?7.43, 4.01?±?1.12 and 3.91?±?0.54 %, for HC in PBS and two river samples, respectively), being 3.2–50.4 times more efficient than the others for PBS and 2.7–252 times for river samples. Efficiencies also depended on the initial virus concentration and aqueous matrixes composition. In consequence, the incorporation of an internal standard like PP7 along the process is useful as a control of the water concentration procedure, the nucleic acid extraction, the presence of inhibitors and the variability of the recovery among replicas, and for the calculation of the sample limit of detection. Thus, the use of a process control, as presented here, is crucial for the accurate quantification of viral contamination. 相似文献