Low mating frequency of queens in the stingless bee<Emphasis Type="Italic"> Scaptotrigona postica</Emphasis><Superscript>1</Superscript> and worker maternity of males

Kin selection models of intracolonial conflict over the maternity of males predict that social hymenopteran workers should favour the production of sons and nephews over brothers when the effective mating frequency (m_e) of the queen is low (m_e<2) but that they should police other workers' reproductive efforts and favour the production of brothers when m_e>2. Stingless bees have been used to support these models in that m_e within the group is considered low and workers are thought often to monopolise the parentage of males. We genetically analysed 20 worker and 20 male pupae from each of 10 colonies of the stingless bee Scaptotrigona postica (= Scaptotrigona aff. depilis) using six microsatellite loci and demonstrate queen monandry in eight nests and apparent low m_e in the other two. However, four colonies contained an additional matriline, possibly due to queen supersedure (serial polygyny), which complicated their genetic structure. Across colonies, workers were responsible for the maternity of 13% of all males. These data are broadly in agreement with predictions from kin selection theory, though the question remains open as to why workers do not secure a greater share of male maternity in this and other stingless bee species in which workers are more closely related to nephews than brothers.     

Odiel River,acid mine drainage and current characterisation by means of univariate analysis

Water pollution caused by sulfide oxidation responds to two geochemical processes: a natural one of temporal patterns, and the 'acid mine drainage', an accelerated process derived from the extractive activity. The Odiel River is located in Southwestern Spain; it flows to the south and into the Atlantic Ocean after joining the Tinto River near its mouth, forming a common estuary. There are three kinds of metallic mining in the Odiel River Basin: manganese, gold and silver, and pyrite mining, the latter being the most important in this basin, which is the object of this study. The main objective of the present study is centred in the characterisation of the sources responsible for the 'acid mine drainage' processes in the Odiel River Basin, through the sampling and subsequent chemical and statistical analyses of water samples collected in three types of sources: mine dumps, active mines and abandoned mines. The main conclusion is that mean pH values in the target area are remarkably lower than those in other active and abandoned mines outside of the study zone. On the contrary, mean values for heavy metal sulfates are much higher. Regarding mine dumps, mean values for pH, sulfates and heavy metals are within a similar range to those data known for areas outside the study zone.     

Heavy Metal Content in Xylem Sap (Vitis Vinifera) from Mining and Smelting Areas

No data are available on the content of heavy metals in the xylem sap of grapevines growing in contaminated areas. The aim of this work was to obtain data on the concentration of Pb, Zn, Cd and Cu in the xylem sap of grapevine (Vitis vinifera) cultivar Monica (ungrafted), growing near contaminated sites: a smelter, an abandoned and an active mine, and to investigate relationships between xylem sap mineral composition and the heavy metal content of the soil. The concentrations of Pb, Zn, Cd and Cu in the sap were enhanced compared to that of the soil, ranging from 4.3 to 611.4 µg Pb , 801 to 6176 µg Zn , 2.5 to 45 µg Cd and 19.8 to 161 µg Cu . Dry matter of xylem sap was significantly related to the heavy metals content in xylem saps, but no significant relationship between the metals in sap and total and DTPA/TEA extractable metal fraction in soil was found.     

Processing and characterization of a new biodegradable composite made of a PHB/V matrix and regenerated cellulosic fibers

In this study, a biodegradable composite consisting of a degradable continuous cellulosic fiber and a degradable polymer matrix—poly(3-hydroxybutyrate)-co-poly(3-hydroxyvalerate (PHB/V with 19% HV)—was developed. The composite was processed by impregnating the cellulosic fibers on-line withPHB/V powder in a fluidization chamber. The impregnated roving was then filament wound on a plate and hot-pressed. The resulting unidirectional composite plates were mechanically tested and optically characterized by SEM. The fiber content was 9.9 ±0.9 vol% by volumetric determination. The fiber content predicted by the rule of mixture for unidirectional composites was 13.8 ±1.4 vol%. Optical characterization showed that the fiber distribution was homogeneous and a satisfactory wetting of the fibers by the matrix was achieved. Using a blower to remove excess matrix powder during processing increased the fiber content to 26.5 ±3.3 vol % (volumetric) or 30.0 ±0.4 vol% (rule of mixture). The tensile strength of the composite parallel to the fiber direction was 128 ±12 MPa (10 vol% fiber) up to 278 ±48 MPa (26.5 vol% fiber), compared to 20 MPa for the PHB/V matrix. The Young’s modulus was 5.8 ±0.5 GPa (10 vol% fiber) and reached 11.4 ±0.14 GPa (26.5 vol% fiber), versus 1 GPa for the matrix.     

Ecosystem approaches to environmental quality assessment

Environmental quality assessment has to focus more on the quality of whole ecosystems, instead of focusing on the direct effects of a specific stressor, because of a more integrated environmetal policy approach. Yet, how can the ecosystem quality be measured? Partly this is a normative question, a question of what is considered good and bad. At the same time, it is a scientific question, dealing with the problem of low the state of a system as complex as an ecosystem could be measured. Measuring all abiotic and biotic components, not to mention their many relationships, is not feasible. In this article we review several approaches dealing with this scientific question. Three approaches are distinguished; they differ in type of variable set and ecosystem model used. As a result of this, the information about the state of the ecosystem differs: ultimate breadth, comprising information about the whole ecosystem, is at the expense of detail, while ultimate detail is at the expense of breadth. We discuss whether the resultant quality assessments differ in character and are therefore suitable to answer different policy questions.     

Ecoregions and ecodistricts: Ecological regionalizations for the Netherlands' environmental policy

For communicating data on the state of the environment to policy makers, various integrative frameworks are used, including regional integration. For this kind of integration we have developed two related ecological regionalizations, ecoregions and ecodistricts, which are two levels in a series of classifications for hierarchically nested ecosystems at different spatial scale levels. We explain the compilation of the maps from existing geographical data, demonstrating the relatively holistic, a priori integrated approach. The resulting maps are submitted to discriminant analysis to test the consistancy of the use of mapping characteristics, using data on individual abiotic ecosystem components from a national database on a 1-km² grid. This reveals that the spatial patterns of soil, groundwater, and geomorphology correspond with the ecoregion and ecodistrict maps. Differences between the original maps and maps formed by automatically reclassifying 1-km² cells with these discriminant components are found to be few. These differences are discussed against the background of the principal dilemma between deductive, a priori integrated, and inductive, a posteriori, classification.     

Shipboard techniques based on flow injection analysis for measuring dissolved Fe, Mn and Al in seawater

An overview is presented of sampling techniques and flow injection analysis (FIA) methods for low concentrations of Fe, Mn and Al in filtered seawater. On the basis of sampling procedures, filtration techniques, accuracy, blanks, detection limits, intercalibration results and oceanographic consistency, the feasibility of these FIA methods was evaluated. It was found that these metals could be measured on board with a minimum risk of contamination and with good accuracy even at low subnanomolar levels (<0.5 nM). Results for reference seawater were in the case of Fe-FIA and Mn-FIA in excellent agreement with the certified values. Data from samples analyzed by Fe-FIA and by cathodic stripping voltametry (CSV) compared well, as did Mn-FIA and GFAAS. All three methods gave results that were mostly in good agreement with data from the same ocean regions published by other research groups. Two different types of surface water sampling were also tested and compared, namely conventional hand filling of a sample bottle from a rubber dinghy away from the ship, and underway pumping of seawater using a 'tow fish'. The latter method gave the best results. Also, conventional membrane filtration and cartridge filtration for large volume filtration were compared using Fe and Al data from water column samples. Good agreement was found for both filter types, although for defining dissolved metal species the latter filter type was preferred.     

Assessing national livestock populations for the production of methane emission inventories

In an effort to accurately assess national methane (CH₄) production levels, many African countries are producing inventories of their national livestock populations. Conducting accurate livestock surveys is an expensive and time-consuming process, but is necessary because the most readily available data on livestock production are often incomplete or unsatisfactory. This paper looks at practical approaches to collecting data on livestock production and on the reproductive parameters for livestock, with special reference to African pastoralist populations, and makes qualified recommendations as to how inventory teams might be able to produce more accurate assessments of their total livestock populations. The methodology used during Nigeria's National Livestock Census (1990–92) serves as a basis for a discussion of the issues.