Effect of nonylphenol surfactants on fungi following the application of sewage sludge on agricultural soils

The effect of nonylphenol on fungi following the application of contaminated sewage sludge on agricultural soil was studied in laboratory experiments. Nonylphenol bioavailability and adsorption were determined in the soil alone and soil-sludge mixtures. Mixing the soil with sludge made it possible to measure the nonylphenol concentration in the soil solution, which comprised between 6.6 x 10(-6) and 3.8 x 10(-7) M, according to the sludge. We then examined the dose-response relationship between nonylphenol concentration in the culture medium and both biomass production and germination rate of the spores from several strains of filamentous fungi. When applied in this range of concentration, nonylphenol was without noticeable short-term effect on these endpoints. Long-term exposure of fungi to nonylphenol was also assessed. The most intensive effect was a strong stimulation of spore production and germination in Fusarium oxysporum Schlechtendahl. Biomass production by the Fusarium strains also increased. Finally, nonylphenol was shown to induce laccase production in Trametes versicolor. We conclude that the potential of nonylphenol to adversely affect several soil fungi remains low.     

Space use in territorial amberwing dragonflies: are residents female maximizers or neighbor minimizers?

Residents of mating territories interact with different categories of conspecifics: females, nonneighbor males, and neighbor males. Interaction with these different types of conspecifics is likely to have different costs and benefits; for example, interactions with females will be beneficial, while interactions with neighbors are more likely to be costly. In this study, we investigated patterns of intrusions and space use in territorial male amberwing dragonflies (Perithemis tenera) to test the idea that residents will adjust their use of space to maximize their beneficial interactions with conspecifics while minimizing their costly interactions with conspecifics. Because territories were arranged linearly around the edge of a pond, each resident had two neighbors, one of which was often closer to the focal resident than the other. Residents experienced more intrusions by neighbors and fewer intrusions by females on the side of their closer neighbor. Residents generally perched on the side of their territory that experienced the fewest intrusions by neighbors and the most intrusions by females, but the pattern was more strongly related to neighbor intrusions than female intrusions. Subsequent to pursuits of neighbors and females, residents tended to shift their perches away from where they pursued neighbors but toward where they pursued females. Nonneighbor intrusions were not affected by neighbor proximity, nor did residents adjust their space use in response to nonneighbor intrusions. Our results suggest that residents do adjust their space use in response to intrusions by conspecifics, that their adjustment depends on the type of conspecific that intruded, and that residents may be using a simple decision rule such as "move away from male intrusions, move closer to female intrusions" to adjust their within-territory space use.Communicated by D. Gwynne     

The relationship of race and gender to managers' ratings of promotion potential

The purpose of this paper was to examine the relationship of race and gender to managers' ratings of promotion potential for a sample of 1268 managerial and professional employees. Hierarchial regression analysis showed that controlling for age, education, tenure, salary grade, functional area, and satisfaction with career support, both race and gender were significantly related to promotion potential. Females were rated lower than males, and Blacks and Asians were rated lower than Whites. There were no interaction effects between race and gender.     

The practice of participatory research and gender analysis in natural resource management

Stakeholder participation is expected to improve the efficiency, equity, and sustainability of natural resource management research and development (R&D) projects by ensuring that research reflects users’ priorities, needs, capabilities, and constraints. Use of participatory methods and tools is growing rapidly; however, there is little systematic evidence about what participation actually means in practice, or about what difference it makes. Based on an inventory of 59 self‐described participatory R&D projects in the area of natural resource management, this article characterizes the typical project and analyzes how stakeholders are selected, how they participate in the research process, and what their involvement means for project costs and impacts. The results suggest that, while projects are generating a range of direct and indirect benefits for participants, more careful attention needs to be paid to achieving equitable impacts. Current practices may lag behind best practices in key areas, such as power sharing and participant selection, and may therefore be missing important contributions from women and other marginalized groups.     

A psychological contract perspective on organizational citizenship behavior

This study examined the contribution of the psychological contract framework to understanding organizational citizenship behavior (OCB) using survey data gathered at three measurement points over a three‐year period from 480 public sector employees. Separating perceived contract breach into its two components (perceived employer obligations and inducements), the data suggest that perceived employer obligations explained unique variance in three dimensions of citizenship behavior (helping, advocacy and functional participation) beyond that accounted for by perceived employer inducements. Employees' acceptance of the norm of reciprocity moderated the relationship between employer inducements and the dimensions of advocacy and functional participation. Employees' trust in their employer moderated the relationship between perceived employer obligations and the dimensions of advocacy and functional participation. Contrary to the hypothesis, procedural or interactional justice did not moderate the relationship between employer inducements and OCB. The implications of the findings for psychological contract research are discussed. Copyright © 2002 John Wiley & Sons, Ltd.     

Effects of chronic external gamma irradiation on growth and reproductive success of Daphnia magna

Aquatic invertebrates (water flea Daphnia magna) were exposed to low dose rates of external gamma radiation (from 0.4 to 31mGyh(-1)) over a 23-day period (i.e. 5 broods). Gamma radiation caused changes in neither survival nor somatic growth. Mass-specific respiration rate was significantly lower at 31mGyh(-1) than in the control. Reproduction was affected through early release and reduced size of broods after 15 days of exposure at 31mGyh(-1) (broods 3-5), resulting in a 21% fecundity decrease at 31mGyh(-1) compared to the control. A decreased resistance of neonates to starvation was observed in relation to dose rates. Possible mechanisms of gamma radiotoxicity for daphnid reproduction and implications for radioprotection are discussed.     

Relationships between spacing behavior and growth rates: A field study of lizard feeding territories

Summary Relationships between spacing behavior and growth rates were investigated in a field experiment with juvenile lizards, Anolis aeneus. The behavioral variable most closely related to juvenile growth was distance moved per unit time. This variable had a curvilinear relationship with growth, such that juveniles moving approximately 400 cm/h grew more rapidly than those traveling either larger or shorter distances per unit time. Daily fluctuations in arthropod abundance were also related to growth rates, with restricted growth during periods of low food availability. Temporal fluctuations in prey and distance traveled per unit time had independent effects on growth; together these two variables accounted for 43% of the variance in growth rate for the juveniles in this study.Territory size, overlap and social status appeared to affect growth indirectly, by influencing distance traveled per unit time. Optimal travel distances of around 400 cm/h were most likely when a juvenile had a relatively exclusive territory of about 0.5 m². High ranking juveniles were more apt to achieve this spacing pattern than were low ranking juveniles, but some high ranking juveniles had very large territories, extensive overlap with subordinates, supraoptimal travel distances and relatively low growth rates. Low ranking juveniles tended to fall into two groups: subordinates, with a small home range overlapping that of a more dominant individual and low travel distances, and floaters, with a large home range overlapping several more dominant individuals and high travel distances. Although a few low ranking juveniles achieved travel distances permitting high growth rates, most had either supra or suboptimal travel distances and relatively low growth rates.     

Temporal reproductive isolation and gametic compatibility are evolutionary mechanisms in the<Emphasis Type="Italic"> Acropora humilis</Emphasis> species group (Cnidaria; Scleractinia)

Patterns of interbreeding between individuals are fundamental to the structure and maintenance of evolutionary boundaries between species. In corals, both hybridisation and reproductive isolation appear to be important evolutionary mechanisms. In this study, I examine evolutionary boundaries using morphological, molecular and reproductive criteria within the Acropora humilis species group at Lizard Island on the Great Barrier Reef, Australia. Five species and seven morphs are recognised on the basis of morphological appearance of features traditionally used to identify corals of the genus Acropora. In a molecular phylogenetic analysis, I examine relationships for the mitochondrial DNAs putative control region, using maximum-parsimony and maximum-likelihood methods. The reproductive criteria explore whether species and morphs are reproductively isolated on the basis of temporal or fertilisation barriers. Timing of gamete maturity is surveyed for each species and morph, from the month prior to and 3 months after the mass spawning. Time of spawning is documented at the levels of night and hour of spawning, and time taken for egg-sperm bundles to separate. Laboratory fertilisation experiments tested the potential of species and morphs to interbreed. High levels of intraspecific and extremely low or zero fertilisation levels between the five species indicated that they are valid species. Based on the combined assessment of morphological, molecular and reproductive criteria, A. humilis and A. gemmifera appear to be the most closely related species, which are most closely related to the remaining species in the following order: A. samoensis, A. monticulosa and A. digitifera. Evidence derived from one or more of these criteria suggest that the morphs (1) are at various stages of divergence from the species with which they share morphological characters, and (2) may indicate possible zones of speciation and hybridisation. Identification of morphs avoided the possibility of taxonomic error and was essential for accurate interpretation of evolutionary boundaries. Confirmation of morphology as an informative character of evolutionary boundaries is of great significance because most coral research projects rely on morphology as the primary tool for identification of species.Communicated by M.S. Johnson, Crawley     

Long-term CO2 enrichment of a forest ecosystem: implications for forest regeneration and succession.

The composition and successional status of a forest affect carbon storage and net ecosystem productivity, yet it remains unclear whether elevated atmospheric carbon dioxide (CO2) will impact rates and trajectories of forest succession. We examined how CO2 enrichment (+200 microL CO2/L air differential) affects forest succession through growth and survivorship of tree seedlings, as part of the Duke Forest free-air CO2 enrichment (FACE) experiment in North Carolina, USA. We planted 2352 seedlings of 14 species in the low light forest understory and determined effects of elevated CO2 on individual plant growth, survival, and total sample biomass accumulation, an integrator of plant growth and survivorship over time, for six years. We used a hierarchical Bayes framework to accommodate the uncertainty associated with the availability of light and the variability in growth among individual plants. We found that most species did not exhibit strong responses to CO2. Ulmus alata (+21%), Quercus alba (+9.5%), and nitrogen-fixing Robinia pseudoacacia (+230%) exhibited greater mean annual relative growth rates under elevated CO2 than under ambient conditions. The effects of CO2 were small relative to variability within populations; however, some species grew better under low light conditions when exposed to elevated CO2 than they did under ambient conditions. These species include shade-intolerant Liriodendron tulipifera and Liquidambar styraciflua, intermediate-tolerant Quercus velutina, and shade-tolerant Acer barbatum, A. rubrum, Prunus serotina, Ulmus alata, and Cercis canadensis. Contrary to our expectation, shade-intolerant trees did not survive better with CO2 enrichment, and population-scale responses to CO2 were influenced by survival probabilities in low light. CO2 enrichment did not increase rates of sample biomass accumulation for most species, but it did stimulate biomass growth of shade-tolerant taxa, particularly Acer barbatum and Ulmus alata. Our data suggest a small CO2 fertilization effect on tree productivity, and the possibility of reduced carbon accumulation rates relative to today's forests due to changes in species composition.     

Seabird eggs as bioindicators of chemical contamination in Chile

Seabird eggs were used as bioindicators of chemical contamination in Chile. Brown-hooded Gull (Larus maculipennis), Kelp Gull (Larus dominicanus), Trudeau's Tern (Sterna trudeaui), Neotropic Cormorant (Phalacrocorax brasilianus), and Pink-footed Shearwater (Puffinus creatopus) eggs were sampled at different breeding sites during the 1990s. Mercury and organochlorines (PCBs, DDT, HCB, HCH, and PCP) were quantified to reveal the interspecific differences, spatial and temporal trends in contamination levels. Trudeau's Tern displayed the highest levels of mercury (486 ng g(-1) wet weight). The highest sumDDT concentrations were measured in Brown-hooded Gulls (726 ng g(-1)). PCB levels were similar among the species (102-236 ng g(-1)), but the composition of the PCB mixture was different in Pink-footed Shearwaters. With the exception of the Brown-hooded Gull, all species studied presented similar and low levels of organochlorines (sumOHa). Residues of PCB and related compounds were not detected in any of the seabird eggs analyzed in Chile. Geographical variation was low, although levels of industrial chemicals were slightly higher in eggs from Concepción Bay, and agricultural chemicals in eggs from Valdivia. Also interannual variation was low, but some evidence was found of decreasing levels in gull eggs throughout the time of the study. The causes of the low levels and small variability in space and time of environmental chemicals in Chilean seabirds are discussed. We propose the use of seabirds in future monitoring of the development of chemical contamination in Chile.