Correction to: Documenting lemming population change in the Arctic: Can we detect trends?

Ambio - In the original published article, some of the symbols in figure 1A were modified incorrectly during the typesetting and publication process. The correct version of the figure is provided...     

Studies on the Measurement of Fluoride in Air and Plant Tissues By the Willard-Winter and Semiautomated Methods

Determinations of F in plant tissues by the Willard-Winter and semiautomated methods have been studied for the presence of determinate and indeterminate errors by multiple linear regression analysis. The results have provided a better understanding of the magnitude of differences between tissue samples required for statistical significance and have suggested that the errors involved are much greater both in number and magnitude than usually assumed. The results have also established that the semiautomated method is a satisfactory alternative to the Willard-Winter method for determining the F content of plant tissues. Investigations of the sources of error in F determinations by the semi-automated method were carried out, and the results indicated a number of ways of reducing errors. Determinations of the F content of air by three methods were compared and studied to estimate the magnitude and locate the sources of error. Here, too, the results indicated that present estimates of the reliability of determinations of the F content of air may be overrated, and they have suggested that improvement in the means of collection of HF is the best way of improving reproducibility.     

The Accumulation of Fluorine by Plants

The accumulation and distribution of fluorine (F) in -plant leaves have been studied to better understand the response of plants to concentrations of atmospheric fluoride (F) that are similar to those found in urban or industrial areas. The results indicate that F from the air can be adsorbed to the surface of leaves as well as accumulated internally and that F in leaves can be translocated outward to the surface as well as upward to the tips. F injury and accumulation can be induced in any desired location on a gladiolus blade by restricting gas exchange of the blade, indicating that all parts of a blade are sensitive to F-induced injury. It is, therefore, suggested that the wide differences often found between plant species and varieties with respect to both susceptibility to injury and degree of F accumulation may be explained by differences in the means of accumulation, trans-location, and distribution of F. F remains in a soluble form in plant leaves and maintains the chemical properties of free, inorganic F. The solubility and mobility of F and the ease of removal from plant tissues indicate that irreversible binding to cellular components does not occur.     

Evaluation of a Low-Cost Transient Mass Measurement System in Vehicle Inspection and Maintenance Testing: Results of a Gordon-Darby Study

Abstract

A study was performed at a Gordon-Darby centralized inspection and maintenance (I/M) test lane in Phoenix, AZ, in December 1999 for the purpose of evaluating the accuracy of production Vehicle Mass Analysis System (VMAS) equipment relative to standard IM240 equipment. Simultaneous transient mass measurements were made on random vehicles using VMAS and IM240 systems on two test lanes during regular I/M testing. Cumulative mass emissions for 846 valid tests were correlated using least-squares regression analysis. Correlation indices were >0.99 for both carbon monoxide (CO) and nitric oxide (NO) and 0.93 for hydrocarbon (HC), and the standard errors of regression were 1.38 g/mi, 0.123 g/mi, and 0.245 g/mi for CO, NO, and HC, respectively. These strong correlation results are reflected by high excess emission identification rates of 99.4% for CO, 99.3% for NO, and 94.5% for HC when applying final IM240 cut points with a <2% error of commission for all pollutants.     

The shifting sea: from soft space to lively space

It is widely acknowledged that marine spatial planning (MSP) should be responsive to the dynamism of the marine environment and the relatively tenuous human relationship with the sea. However, MSP remains conceptualised within rationalistic terms that limit this potential. This article places MSP within the context of spatial theory that holds greater promise for developing more progressive practice. Firstly, the interrelation of MSP with current notions of soft space (less formal, cross-cutting spatialities) is explored, suggesting that MSP is expressing some of the geographical and institutional freedoms of soft space, and may contribute new insights to this concept. Secondly, a progressive framework is developed that builds upon soft space principles. This draws in, on the one hand, underlying relational understandings of space, and on the other hand, insights from marine contexts. This leads to a picture of marine space-being-planned as lively space, expressing, amongst other things, the sea’s materiality. This concept is illustrated through an application of the framework to a strategic MSP exercise for the Baltic Sea region. Finally, it is suggested that MSP itself should be reconceptualised as immersed into this spatial ontology, with the agents and practices of planning taking their place within the wider assemblage of marine actants and relations.     

Skin lipids of the striped plateau lizard (<Emphasis Type="Italic">Sceloporus virgatus</Emphasis>) correlate with female receptivity and reproductive quality alongside visual ornaments

Sex pheromones can perform a variety of functions ranging from revealing the location of suitable mates to being honest signals of mate quality, and they are used in the mate selection process by many species of reptile. In this study, we determined whether the skin lipids of female striped plateau lizards (Sceloporus virgatus) can predict the reproductive quality of females, thereby having the potential to serve as pheromones. Using gas chromatography/mass spectrometry, we identified 17 compounds present in skin lipids of female lizards. Using principal component analysis to compare the skin lipid profile of receptive and non-receptive females, we determined that an uncharacterized compound may allow for chemical identification of receptive mates. We also compared extracted principal components to measures of female fitness and reproductive qualities and found that the level of two 18 carbon fatty acids present in a female’s skin lipids may indicate her clutch size. Finally, we compared the information content of the skin lipids to that of female-specific color ornaments to assess whether chemical and visual cues transmit different information or not. We found that the chroma of a female’s orange throat patch is also related to her clutch size, suggesting that chemical signals may reinforce the information communicated by visual ornamentation in this species which would support the “backup signals” hypothesis for multiple signals.     

Multiple plant exploiters on a shared host: testing for nonadditive effects on plant performance.

The combined impact of multiple plant parasites on plant performance can either be additive (the total damage equals the sum of the individual effects) or nonadditive (synergistic or antagonistic damage). Two statistical models are available for testing the independent (=additive) effects of two factors. Here we suggest that the natural history of the plant-parasite system should motivate the choice of a statistical model to test for additivity. Using in-field, manipulative experiments, we examined the interactions between the herbivorous mite Calacarus flagelliseta Fletchmann, De Moraes and Barbosa (Acari: Eriophyidae), the fungal pathogen Oidium caricae F. Noack (a powdery mildew), and their host plant Carica papaya L. in Hawaii. First, we found that herbivorous mites had a moderate negative effect on powdery mildew: when mites were absent, powdery mildew colonies were larger and more numerous. Second, we showed that each plant parasite, when evaluated alone, significantly reduced several measures of plant performance. Third, we found that the combined impact of mites and mildew on plant performance is mostly additive and, for a few variables, less than additive. Finally, we explored compensatory responses and found no evidence for nonlinearities in the relationship between plant performance and cumulative parasite impact. Plants are almost universally subject to attack by multiple herbivores and pathogens; thus a deeper understanding of how multiple plant parasites shape each other's population dynamics and plant performance is essential to understanding plant-parasite interactions.     

Host location and exploitation by the cleptoparasitic wasp Argochrysis armilla: the role of learning (Hymenoptera: Chrysididae)

Summary The nesting behaviors of many solitary ground-nesting wasps incorporate temporal barriers against would-be cleptoparasites. Nests being excavated are conspicuous but relatively invulnerable to parasites, while nests being provisioned, often several hours to days later, are inconspicuous but highly vulnerable, Argochrysis armilla, a cleptoparasite of solitary ground-nesting wasps, Ammophila spp., bridges the temporal gap between nest excavation and provisioning by (i) visually locating digging hosts, (ii) learning the locations of associated nests, (iii) maintaining surveillance on a series of nests during the hosts' absence, and (iv) ovipositing in nests when the host returns with provisions. Patterns of surveillance and parasitism of Ammophila dysmica nests were generated by the number of cleptoparasites discovering and learning the nest's location during excavation. These results support recent suggestions that learning may play an important role in shaping foraging strategies of insect parasites.     

Effect of potassium inhibition on the thermophilic anaerobic digestion of swine waste.

The inhibition effects of high potassium concentration on thermophilic anaerobic digestion of swine waste were studied. A continuous stirred tank reactor (CSTR), operated at a hydraulic retention time of 10 days and chemical oxygen demand loading of 7.2 to 7.5 g/L/d, was used to digest swine waste and cultivate thermophilic anaerobic microorganisms. To evaluate the toxicity of potassium, batch inhibition tests were also conducted. Without acclimation to potassium, the inhibition threshold beyond which methane production decreased significantly was 3 g K+/L. Volatile fatty acids accumulation was observed during the decline of methane production. Propionic acid was the dominant fatty acid, indicating that propionic acid utilizers were more sensitive to potassium inhibition than acetoclastic methanogens. To test the effect of acclimation on potassium inhibition, the potassium concentration in the CSTR was increased to 6 and 9 g K+/L. Acclimation to 6 g K+/L increased the tolerance of anaerobic inocula to potassium inhibition without significantly reducing the methanogenic activity. The inhibition threshold was increased from 3 g K+/L for unacclimated inocula, to 6 g K+/L for inocula acclimated to 6 g/L of potassium. Acclimation of inocula to 9 g/L potassium further increased the inhibition threshold to 7.5 g K+/L. However, the overall methanogenic activity in the last case was lower than that of unacclimated and 6 g K+/L acclimated inocula.