Patterns of organic osmolytes in two marine bivalves, Macoma balthica, and Mytilus spp., along their European distribution

Patterns of nine intracellular free amino acids (FAA), which are utilized as organic osmolytes for salinity-induced cell volume regulation in marine osmoconformers, were compared in five Macoma balthica populations and seven Mytilus spp. populations along their European distribution. Three types of FAA patterns were classified within both taxa: a northern Baltic type, a southern Baltic type and an Atlantic/Mediterranean type which mainly differ regarding the share of alanine and taurine. Differences are discussed in relation to habitat salinity and population genetics. Along a salinity gradient, the total size of the intracellular FAA pool did not differ between sympatric M. balthica and Mytilus spp., and was significantly correlated with habitat osmolality in a range from 70 to 600 mmol kg⁻¹ H₂O (oligohaline to mesohaline) in both bivalves. In M. balthica, this correlation was mainly based on significant correlations of alanine (15–100 mmol kg⁻¹ DW), glycine (30–100 mmol kg⁻¹ DW) and taurine (0–70 mmol kg⁻¹ DW) with habitat osmolality. In Mytilus spp., only glycine (25–100 mmol kg⁻¹ DW) and taurine (4–180 mmol kg⁻¹ DW) were significantly correlated with habitat osmolality. The concentration of alanine was three times lower in Mytilus spp. than in M. balthica and did not correlate with habitat osmolality. Within a habitat osmolality range from 600 to 1,100 mmol kg⁻¹ H₂O (mesohaline to marine) the concentration of FAA remained constant in both taxa. It is suggested that under marine conditions additional organic osmolytes must become more important for cell volume regulation in Macoma and Mytilus.     

Umweltchemie und ?kotoxikologie in Deutschland Entwicklungstrend des Faches gemessen an der Publikationsproduktivit?t

Fragestellung Wie gestaltet und ggf. ver?ndert sich die wissenschaftliche Produktivit?t der Umweltchemie und ?kotoxikologie in Deutschland? So einfach die Frage klingt: Sie ist schwer zu beantworten, denn auf Fachgebieten, die per se interdisziplin?r sind, sind überlappungen zu Nachbargebieten die Regel und Abgrenzungen schwierig, zum Teil unm?glich, weil in der Literatur nicht erkennbar oder nicht erfasst. Umweltchemie und ?kotoxikologie sind oft „drin“, stehen aber nicht „drauf“ – auf den Institutsnamen, den Projekttiteln oder den Zeitschriftentiteln. Bei in hohem Ma?e interdisziplin?ren Arbeiten – Tendenz steigend – sind wir Wissenschaftler in manchen F?llen sogar selbst verlegen um eine abgrenzende Zuordnung oder empf?nden eine solche als inad?quat oder artifiziell. Ansatz Der Vorstand der Fachgruppe hat die bibliometrische Analyse anhand von Zeitschriftenstichproben als eine probate Herangehensweise für diese Frage gew?hlt. Nicht erfasst werden in einer solchen Stichprobe Arbeiten, die in Zeitschriften ver?ffentlicht wurden, die prim?r nicht der Umweltchemie oder ?kotoxikologie, sondern einem anderen Fach zugerechnet werden. Von der Analyse erfasst werden insbesondere aber die vielen umweltchemischen und ?kotoxikologischen Arbeiten von Wissenschaftlern, deren Arbeitsschwerpunkt in einem anderen Feld liegt und die nur gelegentlich auf unseren Gebieten arbeiten, gleich welche Berufs- und Institutsbezeichnung sie tragen m?gen. Diese Fehlerquelle zu vermeiden, erscheint für relative junge F?cher und stark interdisziplin?re Arbeitsgebiete priorit?r.     

Research needs identified at the second PCB workshop in Brno,Czech Republic,May 7–11, 2002

More than 150 scientists from the Americas, Europe, and Asia met in Brno, Czech Republic, in May 2002 at the Second PCB Workshop, entitled “Recent Advances in the Environmental Toxicology and Health Effects of PCBs”. NIEHS/EPA-Superfund Basic Research Program, the Graduate Center for Toxicology at the University of Kentucky, and the Research Centre for Atmospheric and Environmental Chemistry and Ecotoxicology of Masaryk University, Brno, sponsored the Workshop. At six separate sessions (including posters) the origins, human residues and exposures, actions, biomarkers, risk and remediation issues relating to PCBs were discussed.     

Evaluation of a novel high throughput screening tool for relative emissions of industrial chemicals used in chemical products

Tens of thousands of chemicals are currently marketed worldwide, but only a small number of these compounds has been measured in effluents or the environment to date. The need for screening methodologies to select candidates for environmental monitoring is therefore significant. To meet this need, the Swedish Chemicals Agency developed the Exposure Index (EI), a model for ranking emissions to a number of environmental matrices based on chemical quantity used and use pattern. Here we evaluate the EI. Data on measured concentrations of organic chemicals in sewage treatment plants, one of the recipients considered in the EI model, were compiled from the literature, and the correlation between predicted emission levels and observed concentrations was assessed by linear regression analysis. The adequacy of the parameters employed in the EI was further explored by calibration of the model to measured concentrations. The EI was found to be of limited use for ranking contaminant levels in STPs; the r² values for the regressions between predicted and observed values ranged from 0.02 (p = 0.243) to 0.14 (p = 0.007) depending on the dataset. The calibrated version of the model produced only slightly better predictions although it was fitted to the experimental data. However, the model is a valuable first step in developing a high throughput screening tool for organic contaminants, and there is potential for improving the EI algorithm.     

Resource Selection by Elk in an Agro-Forested Landscape of Northwestern Nebraska

In recent years, elk have begun recolonizing areas east of the Rocky Mountains that are largely agro-forested ecosystems composed of privately owned land where management of elk is an increasing concern due to crop and forage depredation and interspecific disease transmission. We used a Geographic Information System, elk use locations (n = 5013), random locations (n = 25,065), discrete-choice models, and information-theoretic methods to test hypotheses about elk resource selection in an agro-forested landscape located in the Pine Ridge region of northwestern Nebraska, USA. Our objectives were to determine landscape characteristics selected by female elk and identify publicly owned land within the Pine Ridge for potential redistribution of elk. We found distance to edge of cover influenced selection of resources by female elk most and that in areas with light hunting pressure, such as ours, this selection was not driven by an avoidance of roads. Female elk selected resources positioned near ponderosa pine cover types during all seasons, exhibited a slight avoidance of roads during spring and fall, selected areas with increased slope during winter and spring, and selected north- and east-facing aspects over flat areas and areas with south-facing slopes during winter months. We used our models to identified a potential elk redistribution area that had a higher proportion of landcover with characteristics selected by elk in our study area than the current herd areas and more landcover that was publicly owned. With appropriate management plans, we believe elk within the Potential Elk Redistribution Area would predominantly occupy publicly owned land, which would help minimize crop and forage damage on privately owned lands.     

Evaluating the Illinois Stream Valley Segment Model as an Effective Management Tool

Stream habitat assessments are conducted to evaluate biological potential, determine anthropogenic impacts, and guide restoration projects. Utilizing these procedures, managers must first select a representative stream reach, which is typically selected based on several criteria. To develop a consistent and unbiased procedure for choosing sampling locations, the Illinois Department of Natural Resources and the Illinois Natural History Survey have proposed a technique by which watersheds are divided into homogeneous stream segments called valley segments. Valley segments are determined by GIS parameters including surficial geology, predicted flow, slope, and drainage area. To date, no research has been conducted to determine if the stream habitat within a valley segment is homogeneous and if different valley segments have varying habitat variables. Two abutting valley segments were randomly selected within 13 streams in the Embarras River watershed, located in east-central Illinois. One hundred meter reaches were randomly selected within each valley segment, and a transect method was used to quantify habitat characteristics of the stream channel. Habitat variables for each stream were combined through a principal components analysis (PCA) to measure environmental variation between abutting valley segments. A multivariate analysis of variance (MANOVA) was performed on PCA axes 1–3. The majority of abutting valley segments were significantly different from each other indicating that habitat variability within each valley segment was less than variability between valley segments (5.37 ≤ F ≤ 245.13; P ≤ 0.002). This comparison supports the use of the valley segment model as an effective management tool for identifying representative sampling locations and extrapolating reach-specific information.     

Sex-specific nest defense in house sparrows (Passer domesticus) varies with badge size of males

According to indicator models of sexual selection, females can benefit from choosing males with above average epigamic traits, but empirical evidence for such benefits is scarce. Here, we report results from an experiment with 29 pairs of house sparrows (Passer domesticus) where the intensity of nest defense against a mounted mustelid predator was related to the size of the black throat and breast patch (“badge”) in males. Using principal components analysis (PCA), original response variables of both sexes were reduced to two factors: “Approach” to the predator and “Distant warning”. “Approach”, the more risky behavior, increased from small- through medium- to large-badged males and decreased in their females. Since large-badged males have a higher certainty of paternity (i.e. greater benefits from defense) and may be older and more experienced (i.e. incur lower costs), the most likely explanation for male defense intensity increasing with badge size is an improving benefit/cost ratio. The resulting optimal response of their females and evolutionarily stable participation in joint parental care is illustrated by a graphical model. It shows that females would, indeed, benefit directly from choosing large-badged males. This, however, is no proof of a direct evolutionary tie between badge size and paternal behavior, as assumed by indicator models of sexual selection. It may simply represent a spurious relationship, originating from the correlation of badge size and defense with confidence of paternity. Received: 22 September 1997 / Accepted after revision: 3 November 1997     

Learning through EC directive based SEA in spatial planning? Evidence from the Brunswick Region in Germany

This paper presents results of an international comparative research project, funded by the UK Economic and Social Research Council (ESRC) and the Academy for Sustainable Communities (ASC) on the ‘learning potential of appraisal (strategic environmental assessment — SEA) in spatial planning’. In this context, aspects of ‘single-loop’ and ‘double-loop’ learning, as well as of individual, organisational and social learning are discussed for emerging post-EC Directive German practice in the planning region (Zweckverband) of Brunswick (Braunschweig), focusing on four spatial plan SEAs from various administrative levels in the region. It is found that whilst SEA is able to lead to plan SEA specific knowledge acquisition, comprehension, application and analysis (‘single-loop learning’), it is currently resulting only occasionally in wider synthesis and evaluation (‘double-loop learning’). Furthermore, whilst there is evidence that individual and occasionally organisational learning may be enhanced through SEA, most notably in small municipalities, social learning appears to be happening only sporadically.     

Opaque closed chambers underestimate methane fluxes of Phragmites australis (Cav.) Trin. ex Steud

Closed chamber measurements for methane emission estimation are often carried out with opaque chambers to avoid heating of the headspace. However, mainly in wetlands, some plants possess an internal convective gas transport which quickly responds to changes in irradiation. These plants have also been found to often channel a large part of the released methane in temperate fens. We compare methane fluxes derived from transparent versus opaque chambers on Carex-, Phragmites-, and Typha-dominated stands of a temperate fen. Transparent chamber fluxes almost doubled opaque chamber fluxes in the convective transporting Phragmites stand. In Typha, a trend of higher fluxes determined with the transparent chambers was detectable, whereas in Carex, transparent and opaque chamber fluxes did not differ significantly. Thus, opaque chambers bias the outcome of methane measurements, depending on dominant vegetation. We recommend the use of transparent chambers when determining emissions of convective plants or extrapolating fluxes to larger scales.