Effects of a complex archipelago on genetic subdivision of the intertidal limpet Siphonaria kurracheensis

Allozyme variation in the intertidal limpet Siphonaria kurracheensis was examined in 11 populations from the Houtman Abrolhos Islands, Western Australia, and four from the adjacent mainland, to test if the effects of these islands on genetic subdivision should include species with high dispersal. Consistent with extensive planktonic dispersal, genetic subdivision was low, with an average standardized variance in allelic frequencies (F_ST) of 0.010 over 400 km along the mainland, and 0.009 over 70 km in the Abrolhos Islands. Nevertheless, subdivision was statistically significant at the smallest scale examined (about 10 km), showing a pattern of local heterogeneity and large-scale homogeneity, which is common in planktonic dispersers. Among the island populations, heterozygosity was positively correlated with a multivariate index of exposure. The level of heterozygosity at the most exposed island sites is equivalent to that at the (also exposed) mainland sites, whereas it is lower in the most sheltered island sites. Although this indicates that some island populations are less well connected to the major pool of larvae, the overall effect of the archipelago on genetic subdivision is no greater than occurs on the mainland coast. This is contrary to findings in previously studied species with less potential for dispersal, suggesting that the local impediments to dispersal are selective in their effects, and are unlikely to be broadly important for genetic divergence in widely dispersing species.     

The effects of triclopyr on 2,4‐D mineralization in two soils

Abstract

The effects of the herbicide triclopyr (3,5,6‐trichloro‐2‐pyridinyloxyacetic acid) on the mineralization of 2,4‐D (2,4‐dichlorophenoyxacetic acid) in two soils which differed in their histories of prior exposure to the two herbicides were investigated. The relative effects of triclopyr on 2,4‐D mineralization and most probable numbers of 2,4‐D degraders were dependent upon the soil. Triclopyr was shown to increase 2,4‐D mineralization rates in a soil which had been exposed to both 2,4‐D and triclopyr, but decreased the mineralization rate of 2,4‐D and inhibited the increase of most probable numbers of 2,4‐D degraders in a soil that had not been directly exposed to either herbicide.     

Management of traditional hunting of dugongs [Dugong dugon (Müller, 1776)] in the northern Great Barrier Reef,Australia

Some of the largest concentrations of dugongs (Dugong dugon) occur in the coastal waters of eastern Cape York Peninsula, Queensland, Designation of the Great Barrier Reef Marine Park has prompted the development of a program for management of dugong hunting by the aboriginal communities of the region. Assessment of the population by aerial surveys combined with monitoring of the aboriginal hunters' harvest suggest that the take is well below the sustainable yield. However, the reproductive rate of dugongs is so low that it will be a decade before the status of the population can be established. Therefore, a conservative management policy for dugongs is recommended while acknowledging the rights of traditional hunters. Greater participation of the aboriginal communities in the management program is sought to overcome initial misunderstandings and hostility.     

Toward an applied phenomenology: The case of abandoned pier use in Hoboken,New Jersey,USA

This research demonstrates the contribution of phenomenological inquiry within the realm of geographic and environmental planning. The contention is that a focus on the wide range of individual meanings and values ascribed to landscapes, a marginalized element in many planning assessments, can bring out data to more substantively inform decision making, A case study of user meanings imparted to residual waterfront land in Hoboken, New Jersey, USA, suggests that such property provides an array of amenities to residents. Most importantly, it expands the range of recreational activities, creates visual relief from the monotonous urban milieu, and provides scenic vistas to promote an awareness of the quality of life still possible in cities. The study concludes that planners can use phenomenology to generate data for more judicious decision making.     

World diamond industry: 1970–2000

The diamond cartel has remained effective in controlling diamond supplies and prices for a longer period than any other major minerals cartel in the twentieth century. This paper examines the diamond pipeline from mine to the jewellery market. Particular attention is given to the characteristics of diamonds and of the industry structure that make the long-term stability of the cartel possible. The strategies of De Beers Consolidated Diamond Mines in controlling rough gem supplies and prices are examined, and projections are made to 2000. The paper shows that in spite of a projected decrease in the share of total diamond production sold through the De Beers' cartel in the 1990s, the cartel is expected to continue effectively to control supplies and prices.     

Screening method for locating groundwater monitoring wells

The traditional approach to characterizing the extent of groundwater contamination is often phased over a period of several years. A screening method has been developed that allows the investigation process to be reduced to a single phase. Existing data are used to develop a preliminary estimate of the extent of contamination, which is refined by the screening method using groundwater data collected and analyzed in the field. The screening method is applicable at sites with volatile organic compound contamination. Groundwater samples are collected using direct push or drill rig assisted methods, and the groundwater headspace gas is analyzed for the contaminant of interest. The refined estimate is used to locate all of the groundwater monitoring wells necessary to finalize the estimate of the extent of contamination. Therefore, only one investigation phase is required, and time and cost savings are realized with respect to the traditional multiphase approach. The screening method was successfully applied at a CERCLA site in Nebraska with two distinct plumes of TCE-contaminated groundwater. The Nebraska remedial investigation was completed approximately 18 months earlier than the estimated completion of a comparable phased investigation, with a corresponding cost reduction estimated at approximately 10 percent. If data from the screening method were used instead of data from monitoring wells, the estimated cost savings would be over 50 percent. Additional applications and evaluations may lead to industry and regulatory acceptance of the method as a primary characterization tool.     

Drainage Investment and Wetlands Loss: an Analysis of the National Resources Inventory Data

The United States Soil Conservation Service (SCS) conducts a survey for the purpose of establishing an agricultural land use database. This survey is called the National Resources Inventory (NRI) database. The complex NRI land classification system, in conjunction with the quantitative information gathered by the survey, has numerous applications. The current paper uses the wetland area data gathered by the NRI in 1982 and 1987 to examine empirically the factors that generate wetland loss in the United States. The cross-section regression models listed here use the quantity of wetlands, the stock of drainage capital, the realty value of farmland and drainage costs to explain most of the cross-state variation in wetland loss rates. Wetlands preservation efforts by federal agencies assume that pecuniary economic factors play a decisive role in wetland drainage. The empirical models tested in the present paper validate this assumption.     

The use of critical loads maps to assess the effects of sulphur pollution control policies on nature conservation sites in England

Maps showing the critical loads for soil acidification and their exceedence produced by the UK Department of the Environment were examined for the potential impacts on nature conservation in England. Consideration was given to modelled depositions in 2005, after full implementation of the EC Large Combustion Plant Directive (i.e. a 60% reduction in UK sulphur emissions from 1980 levels). A second scenario was also examined, in which the remaining deposition was further reduced by 50% (i.e. an 80% reduction from 1980 levels). No examination was made of the impacts of present day deposition. Critical load exceedence maps for soil acidification were studied at the 1 km square scale for all of England. All SSSIs in England within squares where the critical load will remain exceeded were identified; geological SSSIs were excluded. In these squares 736 biological SSSIs were found to occur. The special interest for 136 of these was not considered to be susceptible to soil acidification damage. The remaining 600 sites are, therefore, considered to be at risk from continued acidification. The 600 sites represent 16.3% of the total number of SSSIs in England. The actual ‘exceeded’ area on these sites was found to represent 26.2% of the total SSSI area of Britain. If emissions are further reduced by 50% the proportions drop to 6.8% and 15.6% respectively. The sites are located throughout England, especially in upland areas of the north and west. However, a large number of sites also occur on exceeded areas on the dry acidic soils of southern and eastern parts of the country. These sites exhibit a wide range of habitat types. Most common are woodlands, peatlands and heathlands. A significant proportion of the nature conservation resource of England will remain at risk from acidification even after full implementation of existing UK government policy commitments. Even a major reduction beyond that commitment is not sufficient to prevent exceedence of critical loads on 250 of these SSSIs. Protection of Britain's natural environment would, therefore, require a very significant reduction in acid emissions beyond that which is currently agreed.