Masekoameng K.E.,South African Council for Scientific and Industrial Research |
Leaner J.,Private Bag |
Dabrowski J.,South African Council for Scientific and Industrial Research
Atmospheric Environment | Year: 2010
Recent studies suggest an increase in mercury (Hg) emissions to the global environment, particularly as a result of anthropogenic activities. This has prompted many countries to complete Hg emission inventories, based on country-specific Hg sources. In this study, information on annual coal consumption and Hg-containing commodities produced in South Africa, was used to estimate Hg emissions during 2000-2006. Based on the information, the UNEP toolkit was used to estimate the amount of Hg released to air and general waste from each activity; using South Africa specific and toolkit based emission factors. In both atmospheric and solid waste releases, coal-fired power plants were estimated to be the largest contributors of Hg emissions, viz. 27.1 to 38.9 tonnes y-1 in air, and 5.8 to 7.4 tonnes y-1 in waste. Cement production was estimated to be the second largest atmospheric Hg emission contributor (2.2-3.9 tonnes y-1), while coal gasification was estimated to be the second largest Hg contributor in terms of general waste releases (2.9-4.2 tonnes y-1). Overall, there was an increase in total atmospheric Hg emissions from all activities, estimated at ca. 34 tonnes in 2000, to 50 tonnes in 2006, with some fluctuations between the years. Similarly, the total Hg emissions released to general waste was estimated to be 9 tonnes in 2000, with an increase to 12 tonnes in 2006. © 2010 Elsevier Ltd.
Podgorski J.E.,ETH Zurich |
Green A.G.,ETH Zurich |
Kgotlhang L.,ETH Zurich |
Kinzelbach W.K.H.,ETH Zurich |
And 3 more authors.
Geology | Year: 2013
The near juxtaposition of the Makgadikgadi Basin (Botswana), the world's largest saltpan complex, with the Okavango Delta, one of the planet's largest inland deltas (technically an alluvial megafan), has intrigued explorers and scientists since the middle of the 19th century. It was clear from early observations that the Makgadikgadi Basin once contained a huge lake, paleo-Lake Makgadikgadi. Several authors have since speculated that this lake also covered wide regions to the north and west of the Makgadikgadi Basin. Our interpretation of unusually high-quality helicopter time-domain electromagnetic (HTEM) data indicates that paleo-Lake Makgadikgadi extended northwestward at least into the region presently occupied by the Okavango Delta. The total area of paleo-Lake Makgadikgadi exceeded 90,000 km2, larger than Earth's most extensive freshwater body today, Lake Superior (North America). Our HTEM data, constrained by ground-based geophysical and borehole information, also provide evidence for a paleo-megafan underlying paleo-Lake Makgadikgadi sediments. © 2013 Geological Society of America.
Mosalagae D.,Private Bag |
Pfukenyi D.M.,University of Zimbabwe |
Matope G.,University of Zimbabwe
Tropical Animal Health and Production | Year: 2011
A cross-sectional questionnaire-based study was conducted to assess milk producers' awareness of milk-borne zoonoses in selected smallholder and commercial dairy farms of Zimbabwe. The questionnaire was designed to obtain information on dairy breeds, milk production, dairy farmers' knowledge and awareness of zoonoses with particular emphasis on milk-borne zoonoses and farmers' behavioural practices that may lead to increased risk of milk-borne zoonoses transmission. A total of 119 dairy farmers were interviewed, and 41.5% were aware of milk-borne zoonoses with a significantly (P < 0.01) higher percentage of commercial dairy farmers (65.0%) being aware compared to smallholder dairy farmers (36.7%). The behavioural practices of dairy farmers observed to increase the risk of milk-borne zoonoses transmission were; consumption of raw milk (68.1%), sale of raw milk to the local public (25.2%), lack of cooling facilities by smallholder farmers (98%), and no routine testing (84.9%) and medical check-ups (89.1%) for milk-borne zoonoses. General hygienic and disease control practices need to be integrated in the milk production process particularly at the smallholder level. Awareness, teaching and training programmes for smallholder dairy farmers can improve disease control in animals and reduce the public health risk of milk-borne zoonoses. © 2010 Springer Science+Business Media B.V.
Fouquet A.,Charles University |
Fouquet A.,University of Sao Paulo |
Ficetola G.F.,University of Milan Bicocca |
Haigh A.,Private Bag |
Gemmell N.,University of Otago
Biological Conservation | Year: 2010
Leiopelma hochstetteri is an endangered New Zealand frog now confined to isolated populations scattered across the North Island. A better understanding of its past, current and predicted future environmental suitability will contribute to its conservation which is in jeopardy due to human activities, feral predators, disease and climate change. Here we use ecological niche modelling with all known occurrence data (N= 1708) and six determinant environmental variables to elucidate current, pre-human and future environmental suitability of this species. Comparison among independent runs, subfossil records and a clamping method allow validation of models. Many areas identified as currently suitable do not host any known populations. This apparent discrepancy could be explained by several non exclusive hypotheses: the areas have not been adequately surveyed and undiscovered populations still remain, the model is over simplistic; the species' sensitivity to fragmentation and small population size; biotic interactions; historical events. An additional outcome is that apparently suitable, but frog-less areas could be targeted for future translocations. Surprisingly, pre-human conditions do not differ markedly highlighting the possibility that the range of the species was broadly fragmented before human arrival. Nevertheless, some populations, particularly on the west of the North Island may have disappeared as a result of human mediated habitat modification. Future conditions are marked with higher temperatures, which are predicted to be favourable to the species. However, such virtual gain in suitable range will probably not benefit the species given the highly fragmented nature of existing habitat and the low dispersal ability of this species. © 2010 Elsevier Ltd.
Tanentzap A.J.,Landcare Research |
Walker S.,Landcare Research |
Theo Stephens R.T.,Private Bag |
Lee W.G.,Landcare Research |
Lee W.G.,University of Auckland
Conservation Letters | Year: 2012
Conservation policy requires reliable estimates of extinction rates that consider the interactions between population size (N) and habitat area. Current approaches to estimating extinction from the endemics-area relationship (EAR) estimate only the minimum number of species that can become extinct because of habitat loss (instantaneous extinction). EARs will therefore underestimate extinction if small populations and/or habitat area (SPHA) commit species to future extinction. We demonstrate this mathematically, by assuming species require a minimum population size of two individuals, and by randomly sampling habitat loss within stem-mapped forest plots. We then develop a general framework for incorporating SPHA effects into EARs that builds upon recent advances introducing N into estimates of extinction. By accounting for effects that modify N, our framework explains extinction debt and reduces the uncertainty associated with future estimates of extinction through carefully qualifying the spatial and temporal context of predictions. © 2012 Wiley Periodicals, Inc.
Elliott G.P.,Private Bag |
Wilson P.R.,Landcare Research |
Taylor R.H.,Landcare Research |
Beggs J.R.,University of Auckland
Biological Conservation | Year: 2010
Common, widespread species are important for ecosystem structure and function. Although such species have declined in some parts of the world, for most ecosystems there is a lack of information about changes in the population status of common species. We studied the abundance of common, widespread forest birds in Nelson Lakes National Park, New Zealand using standardised 5-min bird counts, carried out over a 30-year time span. There was a significant change in the bird community structure during this period. Five native species (bellbird, rifleman, grey warbler, New Zealand tomtit and tui) declined in abundance during the 30 years. All of these declined in abundance at low but not high altitudes, and the decline was substantial for all but New Zealand tomtit and tui. Three other native species increased in abundance (silvereye, yellow-crowned parakeet and New Zealand robin). There was no change in the abundance of introduced blackbirds. We suggest that invasive alien species are the most likely cause of the ongoing declines in common native species. A peak in brushtail possum abundance and the arrival of a new species of Vespula wasp were two large changes in Nelson Lakes forests that occurred during this study. Both are likely to have added to the ongoing impacts of predation by introduced rats and stoats. We suggest that it is necessary to actively manage introduced species in order to maintain populations of widespread, common native bird species in New Zealand. © 2010.
Jolly G.E.,Institute of Geological & Nuclear Sciences |
Keys H.J.R.,Private Bag |
Procter J.N.,Massey University |
Deligne N.I.,Institute of Geological & Nuclear Sciences
Journal of Volcanology and Geothermal Research | Year: 2014
Tongariro volcano, New Zealand, lies wholly within the Tongariro National Park (TNP), one of New Zealand's major tourist destinations. Two small eruptions of the Te Maari vents on the northern flanks of Tongariro on 6 August 2012 and 21 November 2012 each produced a small ash cloud to <. 8. km height accompanied by pyroclastic density currents and ballistic projectiles. The most popular day hike in New Zealand, the Tongariro Alpine Crossing (TAC), runs within 2. km of the Te Maari vents. The larger of the two eruptions (6 August 2012) severely impacted the TAC and resulted in its closure, impacting the local economic and potentially influencing national tourism. In this paper, we document the science and risk management response to the eruption, and detail how quantitative risk assessments were applied in a rapidly evolving situation to inform robust decision-making for when the TAC would be re-opened. The volcanologist and risk manager partnership highlights the value of open communication between scientists and stakeholders during a response to, and subsequent recovery from, a volcanic eruption. © 2014 Elsevier B.V.
Broekema I.,Private Bag |
Overdyck O.,Private Bag
New Zealand Journal of Ecology | Year: 2012
The suitability of line-transect-based distance sampling to robustly estimate population densities of bellbird (Anthornis melanura), kererū (Hemiphaga novaeseelandiae), North island tomtit (Petroica macrocephala toitoi) and tūī (Prosthemadera novaeseelandiae) during concurrent multi-species surveys was investigated. Densities were estimated annually from 2006 to 2009 at three sites within Coromandel Forest Park, New Zealand. The line-transect distance sampling method appeared to be suitable for estimating population densities of kererū, tomtit and tūī for little additional cost than a single-species survey. Potential violation of the three most important distance sampling assumptions was expected to have been minimised for these species; however, distance estimation errors were most likely to bias density estimates. In this study, the line-transect distance sampling method was not found to be suitable for estimating bellbird densities. © New Zealand Ecological Society.
Michaux B.,Private Bag
Biological Journal of the Linnean Society | Year: 2010
The concepts of biogeographical regions and areas of endemism are briefly reviewed prior to a discussion of what constitutes a natural biogeographical unit. It is concluded that a natural biogeographical unit comprises a group of endemic species that share a geological history. These natural biogeographical units are termed Wallacean biogeographical units in honour of the biogeographer A.R. Wallace. Models of the geological development of Indonesia and the Philippines are outlined. Areas of endemism within Wallacea are identified by distributional data, and their relationship to each other and to the adjacent continental regions are evaluated using molecular phylogenies from the literature. The boundaries of these areas of endemism are in broad agreement with earlier works, but it is argued that the Tanimbar Islands are biologically part of south Maluku, rather than the Lesser Sundas, and that Timor (plus Savu, Roti, Wetar, Damar, and Babar) and the western Lesser Sundas form areas of endemism in their own right. Wallacean biogeographical units within Wallacea are identified by congruence between areas of endemism and geological history. It is concluded that although Wallacea as a whole is not a natural biogeographical region, neither is it completely artificial as it is formed from a complex of predominantly Australasian exotic fragments linked by geological processes within a complex collision zone. The Philippines are argued to be an integral part of Wallacea, as originally intended. © 2010 The Linnean Society of London.
Moreki J.C.,Private Bag
Livestock Research for Rural Development | Year: 2010
A study was conducted to assess the performance of village production in Chobe district. A total of 95 village chicken rearers were studied in Serowe, Palapye and Maunatlala. Data collection was by formal and informal interviews, group interviews and direct observation. Secondary sources of data were also reviewed. School children revealed more information on village systems than adults. The national village poultry population was estimated to be about 3.5 million. Village poultry were kept by most rural households in Serowe-Palapye sub-district. Rural families kept village chickens to supplement diet, as source of income and for greeting visitors. Sixty-six percent of the rearers owned 1-20 birds and mean flock size across the villages was 18 birds. Village hens produce three clutches (15.45±4.53 eggs per clutch) in a year and hatchability was estimated to be 81.90%. Low input husbandry methods contributed to high mortality in village chickens. However, the main constraint to village chicken rearing was Newcastle disease (ND), which frequently causes serious mortalities. Losses from other factors, especially predation, accounted for 35%. Traditional disease control remedies predominated. The productivity of village chickens is likely to be improved by allowing chickens to breed during low disease and predation risk periods (e.g., winter and autumn) and by confining birds during high risk periods (e.g., spring and summer months). There is need for new extension strategies that encourage farmers and scientists to work together to promote village chicken rearing.