Gyrfalcon Diet: Spatial and Temporal Variation.

Spatial and temporal variation in respiration in a young ponderosa pine forest during a summer drought

Spatial and temporal variations in soil salinity were measured in a salt marsh in semi‐arid southeastern Spain. A total of 108 samples were taken from the top 20 cm of soil during 2 years in a transect with nine sampling points, established according to plant zonation. Electrical conductivity (EC), pH, Cl‐, SO4 2‐, Ca2+, Mg2+, Na+, and K+ concentrations in saturation extracts were measured in order to determine any pattern of temporal and spatial variation. Correlations between the concentration of different ions, total dissolved salts (TDS), and EC were also examined. Although EC and ion concentrations usually appeared to be well correlated (rs > 0.7, significant atp< 0.01) and followed the same pattern of seasonal variation, a detailed study showed that at high TDS this was not always true. When mean values of TDS ranged between 2592 and 6070 mmolc L‐1, the coefficient of correlation between EC and SO4 2‐ (rs = 0.471, significant at p < 0.01) was lower than that between EC and Na+, K+, Mg2+, and Cl‐(rs ≥ 0.886, significant at p < 0.01). In this range of TDS the coefficient of correlation between EC and Ca2+ was not significant (rs = ‐0.1972). Increased concentrations of certain ions, especially of Ca2+ and SO4 2‐, were not always matched by increases in EC values, which were strongly influenced by ionic relationships, particularly the SO4 2‐/Cl‐and Ca2+/Mg2+ ratios. This indicated that EC was not always a good qualitative or quantitative indicator of the salt content and that, in these cases, the TDS should be used as an indicator of overall salinity.

:Spatial and temporal variation in habitat quality may affect reproductive success and survival of animals. We examined habitat quality of vole-eating Tengmalm’s owls Aegolius funereus for five years (1989-1992 and 1994) under cyclic food conditions in western Finland. We estimated food abundance (the most important component of habitat quality in Tengmalm’s owl) by snap-trapping small mammals on individual territories and by censusing birds (an important alternative prey of owls). We classified territories according to the owl breeding frequency in an earlier 10-year period (mean: 2 breeding attempts per territory) as poor (0-2 breeding attempts) or good ones (> 3 breeding attempts). More Microtus and Clethrionomys voles were snap-trapped on good territories than on poor ones in the increase and peak vole years, but not in the low vole years. Fledgling production, but not egg production, increased with the number of voles snap-trapped on individual territories. The abundance of small birds was higher on good than on poor territories. In the low vole year, more small birds were censused near occupied than unoccupied nest-boxes of owls, which suggests that in poor vole years owls may shift to sites with abundant alternative prey within their territories. In the peak vole year, the size of food caches, food provisioning rate of males and nest defence intensity of females were higher on good than on poor territories. These results suggest that main and alternative food sources may have different importance over time in determining habitat quality and that the abundance of different prey types may affect parental effort and reproductive success of owls. Therefore, studies on species subsisting on cyclically fluctuating food sources should incorporate both temporal and spatial variation in resource abundance.

The in-fauna community inhabiting the surface sediments in the Bahrain waters during 2007-2008 was investigated to describe the spatial and temporal variations between and within Northern and Southern areas. Using a 0.05 m2 van veen grab, samples were collected from 12 sampling stations: 6 stations at each Northern and Southern waters. The samples were collected during Summer and Winter to compare the in-fauna species composition on seasonal basis at each area. In situ water analysis (temperature, salinity, turbidity, pH, dissolved oxygen and depth) and the sediment grain size analysis were carried out at same stations of in faunal samples in order to identify potential environmental key factors causing temporal and spatial variations of in-fauna assemblage. Based on species composition, in-fauna community patterns were identified and evaluated by multivariate analysis Multidimensional Scaling (MDS) using PRIMER V6. A total of 5075 specimens represented by 186 taxon were collected during the study period. Generally, the infauna abundance and number of species in the Northern area was higher than the Southern area and seasonally the samples collected in Summer were relatively more abundant than those collected in Winter. The BIOENV results revealed that the water depth and turbidity are the most influential parameters causing spatial variations of in-fauna community within Northern and Southern areas. On temporal basis, temperature found to be the factor determining major part of the temporal variations within stations associated with Southern area, however turbidity was the influential parameter of temporal variations for stations within the Northern area. On the other hand, the salinity found to be the influential factor affecting the majority of spatial variation between Northern and Southern in-fauna species composition. The present study provides a database on part of marine biodiversity representing a background on benthic community in Bahrain that can be used as a biological indicator to evaluate potential environmental impacts pertaining to developmental projects particularly dredging and reclamation works in coastal and offshore regions.

&amp;lt;p&amp;gt;Mantle earthquakes that occur deeper than the 600 &amp;amp;#176;C isotherm in oceanic transform faults indicate seismic rupturing at conditions where viscous deformation (bulk ductile behavior) is dominant.&amp;amp;#160; However, direct geological evidence of earthquake-related deformation at ambient upper mantle conditions is rare, impeding our understanding of earthquake dynamics in plate-boundary fault systems.&amp;amp;#160; The Bogota Peninsula Shear Zone (BPSZ), New Caledonia, is an ancient oceanic transform fault exhumed from upper mantle depths.&amp;amp;#160; Ductile structures in the BPSZ formed at temperatures &amp;gt; 800 &amp;amp;#176;C and microstructures indicate that differential stress varies spatially and temporally.&amp;amp;#160; Spatial variation is observed as an increase in differential stress with strain toward localized zones of high strain; stress increases from 6&amp;amp;#8211;14 MPa in coarse grained tectonites to 11&amp;amp;#8211;22 MPa within 1&amp;amp;#8211;2 km wide mylonite zones.&amp;amp;#160; Temporal stress variation is observed by the formation of micro-deformation zones that seem to have brittle precursors, are filled with fine-grained recrystallized olivine grains and crosscut the background fabrics in the harzburgites that host them.&amp;amp;#160; The micro-deformation zones are not restricted to the mylonite zones, but rather are located throughout the BPSZ, having affected the protomylonites and the coarse grained tectonites. &amp;amp;#160;The micro-deformation zones record stresses of 22&amp;amp;#8211;81 MPa that are 2&amp;amp;#8211;6 times higher than the background, steady-state stresses in the surrounding mantle rocks.&amp;amp;#160; We interpret the observed spatial and temporal variations in microstructures and stresses in the upper mantle to demonstrate the influence of seismic events in the upper part of the oceanic transform fault system.&amp;amp;#160; We attribute the increase in stress with strain to be the result of imposed localization induced by downward propagation of the seismic rupture into the underlying mantle.&amp;amp;#160; The micro-deformation zones could result from brittle fractures caused by earthquake-related deformation in the mantle section of the transform fault, which are in turn overprinted by ductile deformation.&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;&amp;amp;#160;&amp;lt;/p&amp;gt;&amp;lt;p&amp;gt;Synthesizing the spatial and temporal variations in stresses and microstructures in the Bogota Peninsula Shear Zone we propose a conceptual model where brittle fracturing and shearing take place during coseismic rupture at increased stress, ductile flow at decaying stress is concentrated in the micro-deformation zones during postseismic relaxation, and uniformly distributed creep at low stress occurs in the host-rocks of the micro-deformation zones during interseismic deformation.&amp;amp;#160; The critical result from the studied paleotransform zone is that the fine-grained micro-deformation zones and the mylonites do not represent weak zones. &amp;amp;#160;Instead, they form by dislocation creep at transient high-stress deformation during the seismic cycle. &amp;amp;#160;The spatial distribution of the micro-deformation zones also suggests that repeated stress cycles in oceanic transform faults may not localize strain in pre-existing shear zones but disperse strain across the structure.&amp;lt;/p&amp;gt;

Evapotranspiration represents the combined loss of soil water from the earth’s surface to the atmosphere through evaporation of water from the soil or plant surfaces and transpiration via stomates of the plant. In agricultural production systems these two losses of water represent a major component of the water balance of the crop. If we examine evapotranspiration over time throughout a growing season of a crop then the fractions of evaporation and transpiration will not remain constant. When there is a small plant partially covering the soil then the energy impinging on the soil surface will be used to evaporate water from the soil surface; however, as the crop develops and completely covers the soil then transpiration becomes the dominant process. There is a spatial and temporal aspect to evapotranspiration which exists but is often ignored in our consideration of the dynamics of water loss from the earth’s surface. One of the major questions which exists is how uniform is evapotranspiration over a given production field or over a landscape because of the limited amount of information on the spatial variation of evapotranspiration. There have been a limited number of research studies on the spatial variation in evapotranspiration. Many of these studies utilize remote sensing data as shown by Zhang et al. (2010) in which they developed a spatial-temporal evapotranspiration model for the Hebei Plain in China. They found the temporal variation in evapotranspiration was due to crop growth and the irrigation regime while spatial variation was caused by the type of crop being grown. An aspect of evapotranspiration is the use of reference pan evaporation to provide a surrogate for the atmospheric evaporation and the results from a study by Zhang et al. (2009) showed spatial variation was induced by changes in the driving variables, e.g., windspeed, solar radiation, or temperature. Variations in these parameters would be expected to create spatial differences in evapotranspiration from crop surfaces. Spatial and temporal variation in crop reference evapotranspiration has been studied by Zhang et al. (2010) across a river basin in China and observed the spatial variation in reference evapotranspiration was low in the cool months (January to April) and large in the warm months (May to August). The driving variable inducing the spatial variation in the warm months was most closely related to variation in the available energy among locations. Li et al. (2006) evaluated the combination of remote sensing data combined with surface energy balance to evaluate the spatial variation in evapotranspiration and found the mean values of evapotranspiration were similar across a range of spatial scales. However, the

Spatial and temporal variations in early diagenetic organic matter oxidation pathways in Lower Jurassic mudstones of eastern England

Spatial and temporal variations in salmonid catch per unit effort (C/f) may affect monitoring efforts in lakes and reservoirs. This study evaluated the spatial and temporal variation in gill-net C/f and length structure of captured salmonids in nearshore (≤7.6-m bottom depth) and offshore (&amp;gt;7.6-m bottom depth) areas of two Wyoming reservoirs. Floating experimental gill nets were set as nearshore and offshore pairs at 24 locations in both reservoirs during each of four sampling periods (spring, early summer, late summer, and fall). Salmonid C/f was significantly higher in nearshore areas than in offshore areas during all periods in one reservoir and during all periods except spring in the other reservoir. Mean C/f of rainbow trout Oncorhynchus mykiss was not significantly different between nearshore and offshore areas when water temperatures were 10–13°C in both reservoirs. Length structure of salmonids differed significantly between nearshore and offshore locations and among periods in both reservoirs. These patterns should be considered in both the design and analysis phases of monitoring efforts that use floating experimental gill nets and other sampling gears.

Spatial and temporal variations in light-saturated photosynthetic capacity and needle nitrogen (N) content were investigated in one 8 m tall Japanese cedar (Cryptomeria japonica D. Don) canopy for a full year. The photosynthetic capacity and needle N content in various layers of the canopy were measured every month. Temporal variations in photosynthetic capacity and needle N content expressed on a projected-area basis (Parea, Narea) were similar. Furthermore, both Parea and Narea decreased with increasing depth from the top of the canopy on each sampling date. As a consequence, a significant correlation was observed between Narea and Parea. Temporal variations in photosynthetic capacity and needle N content expressed on a mass basis (Pmass, Nmass) were also similar. Pmass also decreased with increasing canopy depth. However, in contrast to Narea, there was only a slight decrease in Nmass with increasing canopy depth. Hence, the correlation between Nmass and Pmass was lower than the projected-area value. Because Narea was highly correlated with the needle mass per projected-area (NMA), the spatial variation in Narea (and therefore Parea) in the canopy is attributed to the variation in NMA, which decreases as the depth from the top of the canopy increases. Furthermore, the slope of the linear regression between Narea and NMA differed between sampling dates, indicating that the temporal variations in Narea (and therefore Parea) are strongly influenced by Nmass. For most of the sampling dates, a linear regression between Narea and Parea tends to converge into a single line segment. However, on several sampling dates, there was a pronounced decline in Parea below this line segment. This reduction in Parea, which does not accompany a reduction in Narea, seems to be attributable to stomatal limitations induced by the low soil temperature in winter and early spring.

Abstract. Seismic oceanography is a new cross-discipline between geophysics and oceanography that uses seismic reflection data to image and study the oceanic water column. Previous work on seismic oceanography was largely limited to two-dimensional (2D) seismic data and methods. Here we explore and quantify temporal and spatial variations in three-dimensional (3D) seismic oceanography to address whether 3D seismic imaging is meaningful in all directions and how one can take advantage of the variations. From a 3D multichannel seismic survey acquired for oil and gas exploration in the Gulf of Mexico over a 6-month period, a 3D oceanic seismic volume was derived. The 3D seismic images exhibit both temporal and spatial variations of the ocean, and theoretical and data analyses were used to quantify their contribution. Our results suggest that temporal variation is more prominent in the crossline direction than in the inline direction, causing discontinuities in crossline images. However, a series of 3D inline images can be seen as snapshots of the water column at different times, capturing temporal variation of thermohaline structures induced by ocean dynamics. Our findings suggest the potential uses of marine 3D seismic data in studying time-evolving mesoscale ocean dynamics.

Knowledge about the diet of fish-eating predators is critical when evaluating conflicts with the fishing industry. Numerous primary studies have examined the diet of grey sealsHalichoerus grypusand common sealsPhoca vitulinain a bid to understand the ecology of these predators. However, studies of large-scale spatial and temporal variation in seal diet are limited. Therefore this review combines the results of seal diet studies published between 1980 and 2000 to examine how seal diet varies at a range of spatial and temporal scales. Our results revealed extensive spatial variation in gadiform, perciform and flatfish consumption, likely reflecting variation in prey availability. Flatfish and gadiform consumption varied between years, reflecting changes in fish assemblages as a consequence of factors such as varying fishing pressures, climate change and natural fluctuations in populations. Perciform and gadiform consumption varied seasonally: in addition there was a significant interaction between season and seal species, indicating that grey and common seals exhibited different patterns of seasonal variation in their consumption of Perciformes and Gadiformes. Multivariate analysis of grey seal diet revealed spatial variation at a much smaller scale, with different species dominating the diet in different areas. The existence of spatial and temporal variation in seal diet emphasizes that future assessments of the impact of seal populations should not be based on past or localized estimates of diet and highlights the need for up-to-date, site specific estimates of diet composition in the context of understanding and resolving seal/fisheries conflict.

It is essential to establish a baseline in studies using stable isotopes to interpret trophic relationships across ecosystems and through time. Studies in freshwater ecosystems struggle to quantify baseline stable isotopes due to difficulties collecting representative samples, particularly from pelagic habitats. We assessed temporal and spatial variation in δ13C, δ15N, and δ34S in a commonly used pelagic baseline, seston (n = 156), in Lake Erie to understand mechanisms that correlate with baseline stable isotope dynamics in large lakes. Seston contains a wide range of material which can confound stable isotope interpretation, and we examined the utility of element content and ratios to account for variation in sample source. Seston was collected in each of the three basins of Lake Erie from May to October in 2017–2019 at nearshore (&lt;10 m depth) and offshore (&gt;10 m depth) sites. General linear models were conducted on each stable isotope (δ15N, δ13C, and δ34S) and sample composition (variables: %N, %C, %S, C:N, C:S, and N:S) to assess how basin, month, and collection year influenced seston stable isotopes and composition. Sample composition (variables: %N, %C, %S, C:N, C:S, and N:S), which is rarely reported for organisms in stable isotope studies, was constant throughout the sample period with no temporal or spatial trends except for small variations in %C, C:N, C:S, and N:S. This indicated that the temporal and spatial trends observed within the stable isotopes were related to seasonal changes in system processes and plankton community dynamics, with few or minimal changes in the amount of detrital and inorganic material within seston. Values and trends of δ15N, δ13C, and δ34S in seston were comparable to those measured previously in Lake Erie and other Laurentian Great Lakes. All three isotopes increased from May to October of each sample year and varied spatially, δ15N was higher, δ34S was lower, and δ13C was the same in the west basin compared to the central and eastern basins of Lake Erie, which did not differ. These trends probably reflect seasonal changes in plankton community composition and nutrient cycling throughout the lake and are potentially linked to the presence of Microcystis blooms in the western basin during the late summer and autumn. Seston turns over quickly, as shown by the rapid changes in stable isotope values throughout the study, which confounds the investigation of stable isotopes in upper trophic levels, and especially in organisms that have slower tissue turnover and move throughout the lake seasonally. Additionally, the variable composition of seston (e.g., % C, % N, % S, C:N, C:S, N:S) necessitates analysing sample composition to determine the degree of abiotic (e.g., detritus, sediment, particulate organic matter) and biotic (e.g., phytoplankton, zooplankton) content in it.

We carry out high-resolution idealized tropical simulations in a general circulation model with interactive aerosol microphysics to investigate aerosol variations relevant to operational weather forecasting and convection permitting sub-climate scales. We quantify the temporal and spatial variations in aerosol properties. The aerosol structure is driven by aerosol microphysics processes and dynamical processes which influence aerosol properties, emission and transport on scales not resolved by climate models.

The performance of 2 popular methods that use age‐at‐harvest data to estimate abundance of white‐tailed deer is contingent on assumptions about variation in estimates of subadult (1.5 yr old) and adult (≥2.5 yr old) male harvest rates. Auxiliary data (e.g., estimates of survival or harvest rates from radiocollared animals) can be used to relax some assumptions, but unless these population parameters exhibit limited temporal or spatial variation, these auxiliary data may not improve accuracy. Unfortunately maintaining sufficient sample sizes of radiocollared deer for parameter estimation in every wildlife management unit (WMU) is not feasible for most state agencies. We monitored the fates of 397 subadult and 225 adult male white‐tailed deer across 4 WMUs from 2002 to 2008 using radio telemetry. We investigated spatial and temporal variation in harvest rates and investigated covariates related to the patterns observed. We found that most variation in harvest rates was explained spatially and that adult harvest rates (0.36–0.69) were more variable among study areas than subadult harvest rates (0.26–0.42). We found that hunter effort during the archery and firearms season best explained variation in harvest rates of adult males among WMUs, whereas hunter effort during only the firearms season best explained harvest rates for subadult males. From a population estimation perspective, it is advantageous that most variation was spatial and explained by a readily obtained covariate (hunter effort). However, harvest rates may vary if hunting regulations or hunter behavior change, requiring additional field studies to obtain accurate estimates of harvest rates. © 2011 The Wildlife Society.

A micro-based approach to evaluate the effect of water supply on health in Uganda