Differences in embryo production between sympatric species of mysids (family Mysidae) in the shallow coastal waters off Vancouver Island, BC

The ecological importance of mysid (Crustacea: Mysidacea) populations in coastal food webs is not well understood. Although the 10 or more species of epibenthic mysids found in Clayoquot Sound, BC, Canada, form the primary prey resource for seasonally abundant gray whales (Eschrichtius robustus), little is known about their life history. Here, Holmesmysis sculpta dominates multi-species swarms, however there are several potential routes to this state, one of which is higher embryo production. Reproductive capacity is key to the resiliency of local mysid populations and species diversity, in this study I compare one aspect, brood size for the four most commonly found species, H. sculpta, Neomysis rayii, Exacanthomysis davisi, and Columbiaemysis ignota. The number of embryos per brood was found to vary significantly between species; however, individual length is a stronger determinant of brood size. Here, I report previously unknown life history attributes of coastal mysid species, with important consequences for community structure and local marine food webs.     

Human visitation rates to the Apostle Islands National Lakeshore and the introduction of the non-native species Lymantria dispar (L.)

The introduction of non-native species has accelerated due to increasing levels of global trade and travel, threatening the composition and function of ecosystems. Upon arrival and successful establishment, biological invaders begin to spread and often do so with considerable assistance from humans. Recreational areas can be especially prone to the problem of accidental non-native species transport given the number of visitors that arrive from geographically diverse areas. In this paper, we examine camping permit data to the Apostle Islands National Lakeshore in northwestern Wisconsin, USA, from 1999 to 2007 relative to gypsy moth distribution, phenology and outbreak data. During this time, gypsy moth populations became established in this area ahead of the moving population front of the gypsy moth, suggesting anthropogenic introduction. The permit data revealed that the majority of visitors arrived from outside of the gypsy moth established area. However, there was a consistent yearly trend of visitors that arrived from areas of high gypsy moth populations and who arrived during the gypsy moth life stage (egg masses) most likely to be successfully introduced. Using available data on the gypsy moth and its relationship to camping permit data, we describe how recreational managers could optimize park strategies to mitigate unwanted introductions of the gypsy moth as well as develop analogous strategies for managing other biological invaders in recreational areas.     

Leadership self‐efficacy and managers' motivation for leading change

This study develops and tests a leadership model that focuses on managers' motivation for attempting the leadership of change. The construct of leadership self‐efficacy (LSE) is defined, and a measure comprising three dimensions (direction‐setting, gaining followers' commitment, and overcoming obstacles to change) is developed. Based on Bandura's (1986) social cognitive theory, the primary hypothesis is that high LSE managers will be seen by direct reports as engaging in more leadership attempts. Relationships are also proposed between LSE and several factors that are expected to influence this confidence judgment. Managers' organizational commitment and crisis perceptions are modelled as potential moderators of the relationship between LSE and leadership attempts. The model was tested through surveys distributed to managers (n = 150) and their direct reports (n = 415) in a real estate management company and an industrial chemicals firm. Positive relationships (p < 0.05) were found between the first two dimensions of LSE and managers' leadership attempts. An interaction effect involving organizational commitment was discovered for the LSE/overcoming obstacles dimension (p < 0.05). Several positive relationships were found between LSE dimensions and proposed antecedents, including self‐esteem (p < 0.05), subordinates' performance abilities (p < 0.05), and managers' job autonomy (p < 0.05). Copyright © 2002 John Wiley & Sons, Ltd.     

Estimation of Cumulative Frequency Distribution for Carbon Monoxide Concentration from Wind-Speed Data, in Buenos Aires (Argentina)

In this article we apply and test a methodology to estimate cumulative frequency distribution for air pollutant concentration from wind-speed data. We use the inverse relationship after Simpson et al. (Atmospheric Environment, 19, 75–82, 1985) between the opposing percentile values in the statistical distributions for air pollutant concentrations and wind-speed data. This relationship is valid, irrespective of the statistical distributions of both variables, if an inverse relationship between them is also applicable. The available data are five years of 8-h average carbon monoxide concentration and 8-h mean wind-speed, observed in Buenos Aires (Argentina). The performance of the obtained empirical expressions in estimating cumulative frequency distributions for 8-h CO is statistically evaluated. The results show that it is possible to obtain an acceptable cumulative frequency distribution for 8-h CO concentration at the site if the cumulative frequency distribution for wind-speed is known. Q–Q plots show a good agreement between estimated and observed values. From our data, the mean relative error of the estimations was found to be as much as 8.0%.     

Peroxin Puzzles and Folded Freight: Peroxisomal Protein Import in Review

Peroxisomes are organelles that perform a variety of functions, including the metabolism of hydrogen peroxide and the oxidation of fatty acids. Peroxisomes do not possess organellar DNA; all peroxisomal matrix proteins are post-translationally translocated into the organelle. The mechanism of peroxisomal protein translocation has been the subject of vigorous research in the past decade. Many of the proteins (peroxins, abbreviated Pex) that play critical roles in peroxisome biogenesis have been identified through functional complementation of yeast strains and of Chinese hamster ovary cell lines that are defective in peroxisome biogenesis. Researchers are now turning towards biochemical and genetic analyses of these peroxins to define their roles in peroxisome biogenesis and to discover interacting protein partners. Evidence suggests that some of the interacting partners include molecular chaperones. Several current models for peroxisomal protein import are presented.     

Surface retention and photochemical reactivity of the diphenylether herbicide oxyfluorfen

The photochemical behavior of oxyfluorfen [2-chloro-1-(3-etoxy-4-nitrophenoxy)-4-(trifluoromethyl) benzene] on two Greek soils was investigated. Soils were sampled from Nea Malgara and Preveza regions, characterized by a different organic matter content. Soils were spiked with the diphenyl-ether herbicide and irradiation experiments were performed either in the laboratory with a solar simulator (xenon lamp) or outside, under natural sunlight irradiation; other soil samples were kept in the dark to control the retention reaction. Kinetic parameters of both retention and photochemical reactions were calculated using zero-, first- and second- (Langmuir-Hinshelwood) order equations, and best fit was checked through statistical analysis. The soil behaviors were qualitatively similar but quantitatively different, with the soil sampled from the Nea Malgara region much more sorbent as compared with Preveza soil. All studied reactions followed second-order kinetics and photochemical reactions were influenced by retaining capability of the soils. The contributions of the photochemical processes to the global dissipation rates were also calculated. Two main metabolites were identified as 2-chloro-1-(3-ethoxy-4-hydroxyphenoxy)-4-(trifluoromethyl)benzene and 2-chloro-1- (3-hydroxy-4-nitrophenoxy)-4-(trifluoromethyl)benzene.     

Dissolved phosphorus retention and release from a coastal plain in-stream wetland

Dissolved phosphorus (DP) can be released from wetlands as a result of flooding or shifts in water column concentrations. Our objectives were to determine the long-term (1460 d) DP retention and release characteristics of an in-stream wetland, and to evaluate how these characteristics respond to flooding, draining, and changes in DP concentrations. The studied in-stream wetland drains an agriculturally intensive subwatershed in the North Carolina Coastal Plain region. The wetland's DP retention and release characteristics were evaluated by measuring inflow and outflow DP concentrations, DP mass balance, and DP movement across the sediment-water column interface. Phosphorus sorption isotherms were measured to determine the sediment's equilibria P concentration (EPCo), and passive samplers were used to measure sediment pore water DP concentrations. Initially, the in-stream wetland was undersized (0.31 ha) and released 1.5 kg of DP. Increasing the in-stream wetland area to 0.67 ha by flooding resulted in more DP retention (28 kg) and low outflow DP concentrations. Draining the in-stream wetland from 0.67 to 0.33 ha caused the release of stored DP (12.1 kg). Shifts both in sediment pore water DP concentrations and sediment EPCo values corroborate the release of stored DP. Reflooding the wetland from 0.33 to 0.85 ha caused additional release of stored DP into the outflowing stream (10.9 kg). We conclude that for a time period, this in-stream wetland did provide DP retention. During other time periods, DP was released due to changes in wetland area, rainfall, and DP concentrations.     

Quality assurance for the measurements and monitoring of radioactivity in the environment

During the Fifth Framework Programme (FP5) of the European Commission--according to an institutional programme in support to the policy of the European Commission for the implementation of Art. 35 and 36 of the Euratom Treaty as well as in the framework of the OSPAR Convention for the protection of marine environment of the north-east Atlantic--at the Institute for Transuranium Elements (ITU--General Directorate Joint Research Centre--European Commission), a reference laboratory for the measurement of radioactivity in the environment (MaRE laboratory) has been set up. In this paper, the principles and philosophy in order to improve the quality and reliability of analytical data for the measurement and monitoring of radioactivity in the environment under a quality assurance (QA) programme are presented. Examples of how a QA programme at the MaRE laboratory is developed and applied are given. Internal and external quality control (QC) programmes are also discussed.