Transport and transformation of sulfur compounds over East Asia during the TRACE-P and ACE-Asia campaigns

On the basis of the recently estimated emission inventory for East Asia with a resolution of 1×1°, the transport and chemical transformation of sulfur compounds over East Asia during the period of 22 February through 4 May 2001 was investigated by using the Models-3 Community Multi-scale Air Quality (CMAQ) modeling system with meteorological fields calculated by the regional atmospheric modeling system (RAMS). For evaluating the model performance simulated concentrations of sulfur dioxide (SO₂) and aerosol sulfate (SO₄²⁻) were compared with the observations on the ground level at four remote sites in Japan and on board aircraft and vessel during the transport and chemical evolution over the Pacific and Asian Pacific regional aerosol characterization experiment field campaigns, and it was found that the model reproduces many of the important features in the observations, including horizontal and vertical gradients. The SO₂ and SO₄²⁻ concentrations show pronounced variations in time and space, with SO₂ and SO₄²⁻ behaving differently due to the interplay of chemical conversion, removal and transport processes. Analysis of model results shows that emission was the dominant term in regulating the SO₂ spatial distribution, while conversion of SO₂ to SO₄²⁻ in the gas phase and the aqueous phase and wet removal were the primary factors that controlled SO₄²⁻ amounts. The gas phase and the aqueous phase have the same importance in oxidizing SO₂, and about 42% sulfur compounds (25% in SO₂) emitted in the model domain was transported out, while about 57% (35% by wet removal processes) was deposited in the domain during the study period.     

Determinants of mating success in the golden hamster (Mesocricetus auratus) IV. Sperm competition

Summary This study was designed to clarify several aspects of sperm competition in the golden hamster (Mesocricetus auratus). By mating females homozygous for a recessive coat color gene with two males, one homozygous for the dominat gene (agouti) and one homozygous for the recessive (cream), paternity of the resulting young could be determined by day 2 postpartum. When females received 5 consecutive ejaculations from a male of one strain followed by 5 ejaculations from a male of the other strain, there was a significant advantage with respect to litter composition for the male ejaculating first. A mechanism for the first male mating advantage was suggested by the results of an experiment in which the time interval between first and second males was varied. Delays of 30 min between first and second males significantly increased the proportion of young sired by the first male. With a delay of 8 h, the first male sired all of the young. Delays between matings by males of the two strains had greater effects when mating tests began around the time of ovulation, rather than several hours before. Ejaculations in excess of those required for pregnancy initiation were shown to have a two-fold effect. They afforded the first male a measure of protection against displacement by a subsequent male. Conversely, prolonged copulation by the second male resulted in significant displacement of the sperm of a predecessor. The protective effects of multiple ejaculations by the first male were mediated by two mechanisms: the delay in introduction of competing sperm and an increase in the relative concentration of the first male's sperm. Prolonged copulation by the second male also appeared to function through its effect on relative sperm concentrations. Males of these genotypes differed with respect to the relative fertilizing capacity of their cjaculates. When ejaculations from males of the two strains were alternated (thus minimizing mating order effects), agouti males sired over 90% of the young. The time during which mating tests were conducted (relative to the occurrence of ovulation) had no effect on the relative performance of the strains. The effects of prolonged copulation and first male mating advantage demonstrated in this study are consistent with observations of mating behavior under semi-natural conditions. Thus, it appears that patterns of sperm allocation and manipulation, male and female mating strategies, and mating systems have coevolved.     

RIPARIAN ZONE CLASSIFICATION FOR MANAGEMENT OF STREAM WATER QUALITY AND ECOSYSTEM HEALTH1

ABSTRACT: Riparian zones perform a variety of biophysical functions that can be managed to reduce the effects of land use on instream habitat and water quality. However, the functions and human uses of riparian zones vary with biophysical factors such as landform, vegetation, and position along the stream continuum. These variations mean that “one size fits all” approaches to riparian management can be ineffective for reducing land use impacts. Thus riparian management planning at the watershed scale requires a framework that can consider spatial differences in riparian functions and human uses We describe a pilot riparian zone classification developed to provide such a framework for riparian management in two diverse river systems in the Waikato region of New Zealand. Ten classes of riparian zones were identified that differed sufficiently in their biophysical features to require different management. Generic “first steps” and “best practical” riparian management recommendations and associated costs were developed for each riparian class. The classification aims to not only improve our understanding of the effectiveness of riparian zone management as a watershed management tool among water managers and land owners, but to also provide a basis for deciding on management actions.     

Design principles and common pool resource management: an institutional approach to evaluating community management in semi-arid Tanzania

This paper analyses the role of institutions in the management of common pool resources (CPRs) in semi-arid Tanzania. Common property regimes have often been considered inadequate for the management of CPRs because of the problems of excludability, but they are becoming more widely supported as the way forward to overcome the problems of resource use and degradation in developing countries. A series of design principles for long enduring common property institutions have been proposed by Ostrom, but there is concern that they are not applicable to a wide range of real life situations or that they may be specific to certain types of CPR. Here, we compare these principles to the situation prevailing in 12 villages in six districts in semi-arid Tanzania. Data on management institutions were collected through semi-structured interviews and meetings at district and village level. The combined information was used to make a qualitative assessment of the strength with which each design principle appeared to operate in the management of forest, pasture and water resources. Boundaries, conflict and negotiation in CPR management are of key importance in semi-arid regions. However, the need for flexibility in order to deal with ecological uncertainty means that many management institutions would be considered weak or absent according to the design principle approach. This supports the view that the design principles should not be used as a 'blueprint to be imposed on resource management regimes' rather that they provide a framework for investigating common property regimes with the proviso that, certainly for semi-arid regions, they may highlight where management cannot be explained by institutional theory alone.     

Global climate change and contaminants--an overview of opportunities and priorities for modelling the potential implications for long-term human exposure to organic compounds in the Arctic

This overview seeks to provide context and insight into the relative importance of different aspects related to global climate change for the exposure of Northern residents to organic contaminants. A key objective is to identify, from the perspective of researchers engaged in contaminant fate, transport and bioaccumulation modelling, the most useful research questions with respect to projecting the long-term trends in human exposure. Monitoring studies, modelling results, the magnitude of projected changes and simplified quantitative approaches are used to inform the discussion. Besides the influence of temperature on contaminant amplification and distribution, accumulation of organic contaminants in the Arctic is expected to be particularly sensitive to the reduction/elimination of sea-ice cover and also changes to the frequency and intensity of precipitation events (most notably for substances that are highly susceptible to precipitation scavenging). Changes to key food-web interactions, in particular the introduction of additional trophic levels, have the potential to exert a relatively high influence on contaminant exposure but the likelihood of such changes is difficult to assess. Similarly, changes in primary productivity and dynamics of organic matter in aquatic systems could be influential for very hydrophobic contaminants, but the magnitude of change that may occur is uncertain. Shifts in the amount and location of chemical use and emissions are key considerations, in particular if substances with relatively low long range transport potential are used in closer proximity to, or even within, the Arctic in the future. Temperature-dependent increases in emissions via (re)volatilization from primary and secondary sources outside the Arctic are also important in this regard. An increased frequency of boreal forest fires has relevance for compounds emitted via biomass burning and revolatilization from soil during/after burns but compound-specific analyses are limited by the availability of reliable emission factors. However, potentially more influential for human exposure than changes to the physical environment are changes in human behaviour. This includes the gradual displacement of traditional food items by imported foods from other regions, driven by prey availability and/or consumer preference, but also the possibility of increased exposure to chemicals used in packaging materials and other consumer products, driven by dietary and lifestyle choices.     

Linkages between land management activities and stream water quality in a border dyke-irrigated pastoral catchment

This paper describes key linkages between land management activities and stream water quality for a 5230 ha catchment used for intensive pastoral agriculture in southern New Zealand. Due to low annual rainfall and the wide coverage of soils with low available water-holding capacities, flood irrigation of the 2400 ha of flat land within the catchment is an important feature impacting on farm business profitability and stream health. Water quality variables and nutrient and sediment yield estimates are reported for a four-year period. This monitoring shows that some improvement in farm environmental performances would generally be desirable, with stream concentrations of nutrients (N and P), sediment and faecal bacteria regularly exceeding guidelines recommended for surface waters. Field measurements, farm management surveys and farm systems modelling have identified some land management practices that appear to be key sources of many of these pollutants. Border dyke irrigation runoff has a potentially large effect on a range of water quality parameters, due to both the excessive stream flows generated by over-watering and the entrainment of P, N and faecal bacteria in this flow as it passes from land to stream. Stock access to some of the remaining un-fenced lengths of the stream was also recognised as an important land management practice that needed to be addressed if some of the key catchment values identified by stakeholders, such as maintaining a healthy trout fishery and a stream suitable for recreational use, were to be protected. Assessments of the effectiveness and cost-effectiveness of a number of potential mitigation practices identified that managements which targeted reducing irrigation runoff (e.g. by installing bunds or using appropriate watering times) and fencing and planting riparian margins showed the greatest potential to meet these key values with least cost to farm businesses. Other farm practices were also identified that incurred nil or minimal cost while also delivering small or moderate benefits to stream water quality.     

Directional selection by fisheries and the timing of sockeye salmon (Oncorhynchus nerka) migrations.

The timing of migration from feeding to breeding areas is a critical link between the growth and survival of adult animals, their reproduction, and the fitness of their progeny. Commercial fisheries often catch a large fraction of the migrants (e.g., salmon), and exploitation rates can vary systematically over the fishing season. We examined daily records of sockeye salmon (Oncorhynchus nerka) in the Egegik and Ugashik management districts in Bristol Bay, Alaska (USA), for evidence of such temporally selective fishing. In recent years, the early migrants have experienced lower fishing rates than later migrants, especially in the Egegik district, and the median migration date of the fish escaping the fisheries has been getting progressively earlier in both districts. Moreover, the overall runs (catch and escapement) in the Egegik district and, to a lesser extent the Ugashik district, have been getting earlier, as predicted in response to the selection on timing. The trends in timing were not correlated with sea surface temperature in the region of the North Pacific Ocean where the salmon tend to concentrate, but the trends in the two districts were correlated with each other, indicating that there may be some common environmental influence in addition to the effect of selection. Despite the selection, both groups of salmon have remained productive. We hypothesize that this resilience may result from representation of all component populations among the early and late migrants, so that the fisheries have not eliminated entire populations, and from density-dependent processes that may have helped maintain the productivity of these salmon populations.