Multi-stage sampling for large scale natural resources surveys: a case study of rice and waterfowl

Large-scale sample surveys to estimate abundance and distribution of organisms and their habitats are increasingly important in ecological studies. Multi-stage sampling (MSS) is especially suited to large-scale surveys because of the natural clustering of resources. To illustrate an application, we: (1) designed a stratified MSS to estimate late autumn abundance (kg/ha) of rice seeds in harvested fields as food for waterfowl wintering in the Mississippi Alluvial Valley (MAV); (2) investigated options for improving the MSS design; and (3) compared statistical and cost efficiency of MSS to simulated simple random sampling (SRS). During 2000-2002, we sampled 25-35 landowners per year, 1 or 2 fields per landowner per year, and measured seed mass in 10 soil cores collected within each field. Analysis of variance components and costs for each stage of the survey design indicated that collecting 10 soil cores per field was near the optimum of 11-15, whereas sampling >1 field per landowner provided few benefits because data from fields within landowners were highly correlated. Coefficients of variation (CV) of annual estimates of rice abundance ranged from 0.23 to 0.31 and were limited by variation among landowners and the number of landowners sampled. Design effects representing the statistical efficiency of MSS relative to SRS ranged from 3.2 to 9.0, and simulations indicated SRS would cost, on average, 1.4 times more than MSS because clustering of sample units in MSS decreased travel costs. We recommend MSS as a potential sampling strategy for large-scale natural resource surveys and specifically for future surveys of the availability of rice as food for waterfowl in the MAV and similar areas.     

A comparison of results from two test methods for assessing the toxicity of aminotriazole to Selenastrum capricornutum

Two different test methods for assessing the toxicity of aminotriazole to Selenastrum capricornutum are compared. Growth medium composition is demonstrated to have a significant effect on the toxicity of aminotriazole.     

Alcoholism in cockchafers: orientation of male Melolontha melolontha towards green leaf alcohols

Chemical orientation of the European cockchafer, Melolontha melolontha L., a serious pest in agriculture and horticulture, was investigated by field tests and electrophysiological experiments using plant volatiles. In total, 16 typical plant volatiles were shown to elicit electrophysiological responses in male cockchafers. Funnel trap field bioassays revealed that green leaf alcohols (i.e. (Z)-3-hexen-1-ol, (E)-2-hexen-1-ol and 1-hexanol) attracted males, whereas the corresponding aldehydes and acetates were behaviourally inactive. Furthermore, male cockchafers were attracted by volatiles from mechanically damaged leaves of Fagus sylvatica L., Quercus robur L. and Carpinus betulus L. However, volatiles emitted by damaged leaves of F. sylvatica attracted significantly more males than those from the other host plants. Odour from intact F. sylvatica leaves was not attractive to M. melolontha males. Females were not attracted by any of the tested volatile sources. The results suggest that plant volatiles play a similar role as a sexual kairomone in mate finding of M. melolontha, as has been shown for the forest cockchafer, Melolontha hippocastani F. Nevertheless, both species show remarkable differences in their reaction to green leaf alcohols.     

Feeling interrupted—Being responsive: How online messages relate to affect at work

Being constantly connected to others via e‐mail and other online messages is increasingly typical for many employees. In this paper, we develop and test a model that specifies how interruptions by online messages relate to negative and positive affect. We hypothesize that perceived interruptions by online messages predict state negative affect via time pressure and that perceived interruptions predict state positive affect via responsiveness to these online messages and perceived task accomplishment. A daily survey study with 174 employees (a total of 811 day‐level observations) provided support for our hypotheses at the between‐person and within‐person level. In addition, perceived interruptions showed a negative direct association with perceived task accomplishment. Our study highlights the importance of being responsive to online messages and shows that addressing only the negative effects of perceived interruptions does not suffice to understand the full impact of interruptions by online messages in modern jobs.     

Octachlorodibenzo-p-dioxin in wood treatment materials and treated wood

The octachlorodibenzo-p-dioxin (OCDD) concentrations have been determined in aged samples of commercial pentachlorophenol (PCP), in wood protection formulations containing PCP and in wood treated with PCP as a preservative or as an anti-sapstain treatment. The concentrations of OCDD found in the various samples are within the range expected from the amount of commercial PCP initially present in the samples. In view of the known stability of OCDD the results are interpreted as indicating that the formulation, treatment and ageing processes have not led to any substantial conversion of PCP to OCDD; although one result indicates that outdoor exposure of treated samples increased the OCDD concentration by a factor of approximately 2 after $\text{3}\text{1}\text{2}$ years. Analysis of aged samples of treated wood indicate that OCDD is lost much less rapidly from the wood than PCP.     

Spray deposition of two insecticides into surface waters in a South African orchard area

Drift from pesticide spray application can result in contamination of nontarget environments such as surface waters. Azinphos-methyl (AZI) and endosulfan (END) deposition in containers of water was studied in fruit orchards in the Western Cape, South Africa. Additionally, attention was given to the contamination in farm streams, as well as to the resulting contamination of the subsequent main channel (Lourens River) approx. 25 km downstream of the tributary stream inlets. Spray deposit decreased with increasing distance downwind and ranged from 4.7 mg m(-2) within the target area to 0.2 mg m(-2) at 15 m downwind (AZI). Measured in-stream concentrations of both pesticides compared well with theoretical values calculated from deposition data for the respective distances. Furthermore, they were in the range of values predicted by an exposure assessment based on 95th-percentile values for basic drift deposition (German Federal Biological Research Centre for Agriculture and Forestry [BBA] and USEPA). Pesticide deposition in the tributaries was followed by a measurable increase of contamination in the Lourens River. Mortality of midges (Chironomus spp.) exposed for 24 h to samples obtained from the AZI trials decreased with decreasing concentrations (estimated LC50 from field samples = 10 microg L(-1) AZI; lethal distance: LD50 = 13 m). Mortality in the tributary samples averaged 11% (0.5-1.7 microg L(-1) AZI), while no mortality was discernible in the Lourens River samples (0.041 microg L(-1)). The sublethal endpoint failure to form tubes from the glass beads provided was significantly increased at all sites in comparison with the control (analysis of variance [ANOVA], Fisher's protected least significant difference [PLSD], p < 0.01).     

Analysis of polychlorobiphenyls from used transformers for polychlorodibenzofurans

The results of analyses for polychlorodibenzofuran (PCDF) content in two samples of polychlorobiphenyl (PCB) from used electrical transformers are presented and discussed. In neither sample was there evidence for enhanced PCDF concentrations even though one of them had been subjected to overheating while in service.     

Polychlorodibenzo-p-dioxins and dibenzofurans in technical pentachlorophenol - results of a collaborative analytical exercise

Results of analyses of eight samples of technical pentachlorophenol conducted by three different analytical methods are presented and discussed.     

Long term changes in polychlorodibenzo-p-dioxin concentrations in wood treated with technical pentachlorophenol

Wood samples treated with technical pentachlorophenol (PCP), technical sodium pentachlorophenoxide (NaPCP) and octachlorodibenzo-p-dioxin have been exposed outdoors for periods up to $\text{2}\text{1}\text{2}$ years. Analysis of extracts from the samples show that photolytic reductive dechlorination of highly chlorinated dibenzo-p-dioxins to less chlorinated isomers occurs. However there is no discernible increase in polychlorodibenzo-p-dioxin concentrations in the technical PCP treated wood presumably because further photolytic reactions and volatilisation compete effectively with the photolytic formation. There is no evidence for formation of octachlorodibenzo-p-dioxin (OCDD) in technical PCP treated wood in this study, probably because photolytic destruction and volatilisation compete effectively with formation reactions when the initial OCDD concentration is relatively high.