Macrozoobenthos diversity in an oxygen minimum zone off northern Namibia

A benthological survey in the Benguela upwelling area off northern Namibia (located at 17.3°S and water depth ranging between 26 and 117 m) showed the concentration of dissolved oxygen and the accumulation of organic-rich sediments to control macrozoobenthic community patterns. In contrast to highly biodiverse nearshore areas with well-structured shell deposits of the brachiopod Discinisca tenuis (Sowerby 1847), the benthic community in the oxygen minimum zone (OMZ) decreased strongly in species numbers. Nevertheless, a well-established community ranging from 13 to 31 species persisted. Species densities (300–3,350 ind m⁻²) and biomass (4–109 g afdw/m²) were surprisingly high for areas with near bottom oxygen concentrations from 0.06 to 0.88 ml l⁻¹. In contrast to OMZ’s of other upwelling areas, where the benthic macrofauna is generally dominated by small-bodied polychaetes, off Namibia larger key organisms like the bivalve Nuculana bicuspidata (Gould 1845) and the snail Nassarius vinctus (Marrett 1877) accounted for a large proportion of the macrozoobenthos >1 mm. This is supposed to have a distinct effect on the functional properties of the sediments.

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Review of the reticulated python (Python reticulatus Schneider, 1801) with the description of new subspecies from Indonesia

The geographically widespread Python reticulatus, the world's longest snake, has been largely neglected by taxonomists. Dwarfed individuals from Tanahjampea Island, Indonesia, differ strikingly in morphology. Phylogenetic relationships were analyzed using a 345-bp fragment of the cytochrome b gene for 12 specimens from different populations. Both genetic differences and morphological characters distinctly revealed two taxonomic subunits. The island populations of Tanahjampea and Selayar form two monophyletic lineages, supported by high bootstrap values, with distinct differences in color pattern and scalation. We consider these forms to represent two new subspecies. The Tanahjampea form is genetically related to populations of the Sunda Islands and mainland Southeast Asia, whereas the Selayar form is related to populations of Southwest Sulawesi. We conclude that, due to strong directional surface currents in this region, gene flow between Tanahjampea and Selayar is prevented. Sea-level changes during the Pleistocene probably contributed to the isolation of the two taxa described. Aspects of ecology and conservation status are briefly discussed. Electronic supplementary material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s00114-002-0320-4.     

Effects of Management on Understory Diversity in the Forest Ecosystems of Northern Spain

Pine plantations are an alternative to marginal agriculture in many countries, and are often presented as an option that improves biodiversity. However, these plantations can have adverse environmental effects if improperly managed. To evaluate the effect of forest management practices on biodiversity, the diversity, species richness, dominance and frequency of understory woody plant species in different forests of the Basque Country (northern Spain) were compared. Plantations of exotic conifers (Pinus radiata [D.] Don) of different ages were compared with deciduous forests of Quercus robur L. and Fagus sylvatica L. The effects of different types and intensities of management were taken into account. The differences observed were mainly conditioned by the intensity of forestry management, although the response varied according to forest type and age. In unmanaged pine plantations, the diversity and species richness of the understory increased rapidly after planting (while dominance decreased), remained stable in the intermediate age range, and reached a maximum in plantations more than 25 years of age. Management practices resulted in decreased understory diversity and species richness, as well as greater dominance. This was more pronounced in younger than in older stands. Moderate management, however, favored a greater diversity of the understory in deciduous forests. The species composition of the plantations and deciduous forests were different, the latter having a wider range of characteristic species. Knowledge of how forestry practices influence biodiversity (in terms of diversity, richness, dominance, and species composition) may allow predictions to be made about the diversity achievable with different management systems.     

Braucht Substitution mehr Staat oder mehr Markt?

Ziel und Hintergrund

In den bisherigen REACH-Verordnungsentwürfen wird als einer der wichtigen Gründe für die Gesetzes-initiative ‘die Schaffung von Anreizen für die Substitution gefährlicher durch weniger gefährliche Stoffe’ genannt (REACH 2003, 61). Damit wird die Frage aktuell, was denn Unternehmen als Wirtschaftssubjekte ‘anreizen’ oder eben auch ‘nicht anreizen’ kann, gefährliche chemikalien zu substituieren: Welche Marktkräfte wirken bereits positiv, die durch regulative Vorgaben eventuell verstärkt werden können, und welche die Substitution behindernden Marktkräfte sollten durch regulative Maßnahmen abgeschwächt werden?

Schwerpunkte

Die Autoren untersuchen auf Basis ihrer Vorarbeiten und Fallstudien zur Substitution die Rahmenbedingungen — Treiber und blockierende Faktoren — für Substitution. Dabei werden auch aktuelle Positionen zur Substitutionsproblematik einbezogen, so z.B. die Stellungnahme des Ausschusses für Umwelt, Gesundheit und Sicherheit der Royal Society of Chemistry (UK), des UK Chemicals Stakeholder Forums sowie die gegenwärtigen Kompromisse zwischen Europäischem Rat und Europäischem Parlament zur Regelung der Substitution unter REACH.

Ergebnisse und Schlussfolgerungen

Gegenwärtig fördern weder die Marktdynamik noch die Gesetzgebung Substitution effektiv genug. Die Unternehmen selbst sind zögerlich, wenn Kosten und Haftungsfragen sowie Kundenprioritäten der Substitution entgegenstehen. Substitution wird vom Gesetzgeber oft nur als Rahmengebot, als Generalklausel, als Anspruch, als Vorrangstrategie oder als Priorität gefordert. Dennoch gibt es sowohl in der Gesetzgebung als auch in der Marktentwicklung positive Ansätze, die regulativ unterstützt werden können.

Perspektive

Der entscheidende Punkt für die Frage der regulativen Substitutionsvorgaben ist, auf welche Weise der Staat die Marktdynamik durch Setzen von Innovationszielen befördern kann. Der Staat sollte in Kooperation mit den Stakeholdern in technischen Dossiers die bekannten Substitutionsmöglichkeiten und Risikominderungsmaßnahmen zusammen stellen, einen Realisierungszeitpunkt vorgeben, Mindeststandards vorschrieben und auch detaillierte Regulation androhen, falls nichts geschieht. Eine case-to-case-Beurteilungs-Methode ist der Substitutionsproblematik in der Regel angemessen, um den Aufwand und die erforderlichen Maßnahmen annähernd genau zu bestimmen.     

Chemical reactivities of ambient air samples in three Southern California communities

The potential adverse health effects of PM_2.5 (particulate matter with an aerodynamic diameter <2.5 μm) and vapor samples from three communities that neighbor railyards, Commerce (CM), Long Beach (LB), and San Bernardino (SB), were assessed by determination of chemical reactivities attributed to the induction of oxidative stress by air pollutants. The assays used were dithiothreitol (DTT)- and dihydrobenzoic acid (DHBA)-based procedures for prooxidant content and a glyceraldehyde-3-phosphate dehydrogenase (GAPDH) assay for electrophiles. Prooxidants and electrophiles have been proposed as the reactive chemical species responsible for the induction of oxidative stress by air pollution mixtures. The PM_2.5 samples from CM and LB sites showed seasonal differences in reactivities, with higher levels in the winter, whereas the SB sample differences were reversed. The reactivities in the vapor samples were all very similar, except for the summer SB samples, which contained higher levels of both prooxidants and electrophiles. The results suggest that the observed reactivities reflect general geographical differences rather than direct effects of the railyards. Distributional differences in reactivities were also observed, with PM_2.5 fractions containing most of the prooxidants (74–81%) and the vapor phase most of the electrophiles (82–96%). The high levels of the vapor-phase electrophiles and their potential for adverse biological effects point out the importance of the vapor phase in assessing the potential health effects of ambient air.

Implications:?PM_2.5 and its corresponding vapor phase, containing semivolatile organics, were collected in three communities in the Los Angeles Basin and examined with toxicologically relevant chemical assays. The PM_2.5 phase contained most of the prooxidants and the vapor phase contained most of the electrophiles, whose content was highest in summer samples from a receptor site that reflected greater photochemical processing of the air parcel during its transport. As electrophiles initiate both adverse and adaptive responses to foreign substances by biological systems, their presence in the vapor phase emphasizes the importance of this phase in the overall health effects of ambient air.