Host intra-clutch variation,cuckoo egg matching and egg rejection by great reed warblers

Prevailing theory predicts that lower levels of intra-clutch variation in host eggs facilitate the detection of brood parasitism. We assessed egg matching using both human vision and UV-VIS spectrophotometry and then followed the nest fate of great reed warblers naturally parasitised by European cuckoos. Rejection was predicted by the following three variables: matching between cuckoo and host eggs on the main chromatic variable defined by principal components analysis of the egg spectra (which has a strong loading in the UV); the number of host eggs in the nest; and human estimates of intra-clutch variation. The first variable is not correlated to human estimates of matching, which do not predict rejection. In line with another recent study, rejection rates were predicted by higher levels of intra-clutch variation in the host eggs, suggesting that higher rather than lower levels of intra-clutch variation can facilitate the discrimination of cuckoo eggs by hosts. We suggest that the importance of intra-clutch variation is context dependent, with intra-clutch variation being important when there is good matching between the host and the cuckoo eggs. Our results also suggest that both spectrometric and human visual assessments of egg matching and intra-clutch variation are prudent: the former provide the best method of estimating reflectance variation, whereas the latter include some assessment of patterns of maculation.     

Degree of phosphorus saturation thresholds in manure-amended soils of alberta

The risk of P losses from agricultural land to surface and ground water generally increases as the degree of soil P saturation increases. A single-point soil P sorption index (PSI) was validated with adsorption isotherm data for determination of the P sorption status of Alberta soils. Soil P thresholds (change points) were then examined for two agricultural soils after eight annual applications of different rates of cattle manure and for three agricultural soils after one application of different rates of cattle manure. Linear relationships were found between soil-test P (STP) levels up to 1000 mg kg(-1) and desorbed P in the five Alberta soils. Weak linear relationships were also found between STP and runoff dissolved reactive phosphorus (DRP) in three of these soils. Change points for the degree of P saturation (DPS) were detected in four of the five soils at 3 to 44% for water-extractable P (WEP) and at 11 to 51% for CaCl(2)-extractable P (CaCl(2)-P). Change points were not found for DPS or runoff DRP. Overall DPS thresholds for the five soils combined were 27% for WEP and 44% for CaCl(2)-P at a critical desorbable-P value of 1 mg L(-1). The corresponding STP levels (44 mg kg(-1) for WEP and 71 mg kg(-1) for CaCl(2)-P) are similar to agronomic thresholds for crops grown on Alberta soils. Soluble P losses in overland flow and leaching may be greater in soils with DPS values that exceed these thresholds than in soils with lower DPS values.     

Validation of Satellite Precipitation Adjustment Methodology From Seven Basins in the Continental United States1

Tobin, Kenneth J. and Marvin E. Bennett, 2012. Validation of Satellite Precipitation Adjustment Methodology From Seven Basins in the Continental United States. Journal of the American Water Resources Association (JAWRA) 48(2): 221‐234. DOI: 10.1111/j.1752‐1688.2011.00604.x Abstract: The precipitation science community has expressed concern regarding the ability of satellite‐based precipitation products to accurately capture rainfall values over land. There has been some work that has focused on addressing the deficiencies of satellite precipitation products, particularly on the adjustment of bias. This article outlines a methodology that adjusts satellite products utilizing ground‐based precipitation data. The approach is not a simple bias adjustment, but is a three‐step process that transforms a satellite product based on a ground‐based precipitation product (NEXRAD‐derived Multisensor Precipitation Estimator [MPE] product or rain‐gauge data). The developed methodology was successfully applied to seven moderate‐to‐large sized watersheds from continental United States (CONUS) and northern Mexico over a spectrum of climatic regimes ranging from dry to humid settings. Methodology validation is based on comparison of observed and simulated streamflow generated with SWAT (Soil and Water Assessment Tool) model using unadjusted and adjusted precipitation products as input. Streamflow comparison is based on mass balance error and Nash‐Sutcliffe efficiency coefficient. Finally, the contribution of how adjustment to correct misses, false alarms, and bias impacts adjusted datasets and the potential impact that the adjustment methodology can have on hydrological applications such as water resource monitoring and flood prediction are explored.     

Moderating effects of political skill,perceived control,and job‐related self‐efficacy on the relationship between negative affectivity and physiological strain

The present study examined whether employees high in negative affectivity (NA) are destined to experience strain at a higher level than those low in NA. We used data collected from 230 employees to investigate the moderating effects of political skill, as a form of interpersonal control, on the relationship between NA and physiological strain. As hypothesized, NA was positively related to physiological strain (i.e., facial muscle tension as measured by electromyography (EMG)), and political skill buffered this effect such that the relationship was weaker among employees who were higher in political skill. Tests of mediated moderation further suggested the means by which political skill moderates the NA/strain relationship; specifically, the results were consistent with the idea that perceived control and, in turn, job‐related efficacy explain the moderating effect of political skill. Strengths and limitations of the study, practical implications, and directions for future research are discussed. Copyright © 2007 John Wiley & Sons, Ltd.     

Workplace offense and victims' reactions: the effects of victim‐offender (dis)similarity,offense‐type,and cultural differences

This study examined the effects of workplace offenders' characteristics and offense‐type on victims' reactions. Responses from 352 employed graduate students in the U.S. and South Korea to a hypothetical offense incident revealed that employees from the U.S. and Korea differ in their expressed desirability of avoiding, seeking revenge against, and reconciling with an offending coworker depending on the offenders' similarity/dissimilarity to the victim and on the type of offense. As expected, Koreans (but not U.S. Americans) were more likely to avoid and to seek revenge on a coworker whose offensive remark was group‐ rather than personally‐directed. In addition, Koreans were most motivated to reconcile when an offensive remark came from a similar rather than dissimilar coworker and when the offense targeted them personally (not their group). However, U.S. Americans were most motivated to reconcile when an offensive remark came from a similar rather than dissimilar other and when the offense targeted their group (not them personally). Copyright © 2008 John Wiley & Sons, Ltd.     

Long‐distance flights and high‐risk breeding by nomadic waterbirds on desert salt lakes

Understanding and conserving mobile species presents complex challenges, especially for animals in stochastic or changing environments. Nomadic waterbirds must locate temporary water in arid biomes where rainfall is highly unpredictable in space and time. To achieve this they need to travel over vast spatial scales and time arrival to exploit pulses in food resources. How they achieve this is an enduring mystery.  We investigated these challenges in the colonial‐nesting Banded Stilt (Cladorhynchus leucocephalus), a nomadic shorebird of conservation concern. Hitherto, Banded Stilts were hypothesized to have only 1–2 chances to breed during their long lifetime, when flooding rain fills desert salt lakes, triggering mass‐hatching of brine shrimp. Over 6 years, we satellite tagged 57 individuals, conducted 21 aerial surveys to detect nesting colonies on 14 Australian desert salt lakes, and analyzed 3 decades of Landsat and MODIS satellite imagery to quantify salt‐lake flood frequency and extent. Within days of distant inland rainfall, Banded Stilts flew 1,000–2,000 km to reach flooded salt lakes. On arrival, females laid over half their body weight in eggs. We detected nesting episodes across the species’ range at 7 times the frequency reported during the previous 80 years. Nesting colonies of thousands formed following minor floods, yet most were subsequently abandoned when the water rapidly evaporated prior to egg hatching. Satellite imagery revealed twice as many flood events sufficient for breeding‐colony initiation as recorded colonies, suggesting that nesting at remote sites has been underdetected. Individuals took risk on uncertain breeding opportunities by responding to frequent minor flood events between infrequent extensive flooding, exemplifying the extreme adaptability and trade‐offs of species exploiting unstable environments. The conservation challenges of nest predation by overabundant native gulls and anthropogenic modifications to salt lakes filling frequencies require investigation, as do the physiological and navigational mechanisms that enable such extreme strategies.     

Reservoir sedimentation and environmental degradation: assessing trends in sediment-associated trace elements in Grenada Lake, Mississippi

Sediments impounded within flood control reservoirs are potentially important archives of environmental and geomorphic processes occurring within drainage basins. The concentrations of select sediment-associated trace elements were assessed within the impoundment of Grenada Lake, a relatively large flood control reservoir in Mississippi with a history of contaminant bioaccumulation in fish. The post-construction sediments (after 1954) are discriminated from the pre-construction sediments (before 1954) based on depth variations in sediment texture and 137Cs emissions. The concentrations of select trace elements of the post-1954 sediments all are statistically greater than the pre-1954 sediments, and these same sediments also are enriched in clay. Once these concentrations are normalized by clay content, all trace elements in the post-1954 sediments are lower in concentration than the pre-1954 normalized sediments. Moreover, the trace elements when normalized by clay or Al content show virtually no change vertically (over time) within the reservoir impoundment. This suggests that the sources of these sediment-associated trace elements within Grenada Lake, whether natural or anthropogenic, have not changed appreciably over the lifespan of the reservoir and that the degradation of sedimentologic and ecologic indices within the lake are due to the sequestration of clay or clay-sized materials.     

Influence of vegetation in mitigation of methyl parathion runoff

A pesticide runoff event was simulated on two 10 m x 50 m constructed wetlands (one non-vegetated, one vegetated) to evaluate the fate of methyl parathion (MeP) (Penncap-M). Water, sediment, and plant samples were collected at five sites downstream of the inflow for 120 d. Semi-permeable membrane devices (SPMDs) were deployed at each wetland outflow to determine exiting pesticide load. MeP was detected in water at all locations of the non-vegetated wetland (50 m), 30 min post-exposure. MeP was detected 20 m from the vegetated wetland inflow 30 min post-exposure, while after 10d it was detected only at 10 m. MeP was measured only in SPMDs deployed in non-vegetated wetland cells, suggesting detectable levels were not present near the vegetated wetland outflow. Furthermore, mass balance calculations indicated vegetated wetlands were more effective in reducing aqueous loadings of MeP introduced into the wetland systems. This demonstrates the importance of vegetation as sorption sites for pesticides in constructed wetlands.     

Mitigation of azinphos-methyl in a vegetated stream: comparison of runoff- and spray-drift

The effectiveness of aquatic macrophytes in reducing runoff- and spray-drift-induced azinphos-methyl (AZP) input was compared in a vegetated stream. Water, sediment and plant samples were taken at increasing distances from a point of input during a spray-drift event and two runoff (10 and 22 mm/day) events. Peak concentrations of AZP decreased significantly (R2=0.99; p<0.0001; n=5) from 0.24 microg/l to 0.11 microg/l during the 10mm runoff event. No reduction took place during the 22 mm event. AZP concentrations were reduced by 90% following spray-drift input, with peak concentrations decreasing significantly (R2=0.93; p=0.0084; n=5) from 4.3 microg/l to 1.7 microg/l with increasing distance from the point of input. Plant samples taken after the spray-drift event showed increased AZP concentrations in comparison to before the event indicating sorption of the pesticide to the macrophytes. Although peak concentrations of AZP were as effectively mitigated during the 10mm runoff event as during the spray-drift event, predictive modelling revealed that maximum concentrations expected during a worst-case scenario 10mm runoff event (0 days after application) are an order of magnitude lower than what can be expected for a worst-case spray-drift and 22 mm runoff event, suggesting that spray-drift-derived pesticide concentrations are more effectively mitigated than those of runoff.