Combining Aboriginal and Non-Aboriginal Knowledge to Assess and Manage Feral Water Buffalo Impacts on Perennial Freshwater Springs of the Aboriginal-Owned Arnhem Plateau, Australia

Aboriginal land managers have observed that feral Asian water buffalo (Bubalis bubalis Lydekker) are threatening the ecological and cultural integrity of perennial freshwater sources in Arnhem Land, Australia. Here we present collaborative research between the Aboriginal Rangers from Warddeken Land Management Limited and Western scientists which quantified the ground-level impacts of buffalo on seven perennial freshwater springs of the Arnhem Plateau. A secondary aim was to build the capacity of Aboriginal Rangers to self-monitor and evaluate the ecological outcomes of their land management activities. Sites with high buffalo abundance had significantly different ground, ground cover, and water quality attributes compared to sites with low buffalo abundance. The low buffalo abundance sites were characterized by tall herbaceous vegetation and flat ground, whereas wallows, bare ground, and short ungrazed grasses were indicators of sites with high buffalo abundance. Water turbidity was greater when buffalo abundance was high. The newly acquired monitoring skills and derived indicators of buffalo damage will be used by Aboriginal Rangers to assess the ecological outcomes of their future buffalo control efforts on the Arnhem Plateau.     

Effects of incremental increases in silt load on the cardiovascular performance of riverine and lacustrine rock bass, Ambloplites rupestris

Rock bass (Ambloplites rupestris) are a widespread centrarchid species with both riverine and lacustrine populations. After precipitation events, rivers often carry elevated silt loads, where as lakes generally remain free from suspended silt and sediment. To examine the physiological effects of silt on rock bass, we conducted a series of experiments using fish from Lake Opinicon and the Grand River in Ontario. Ultrasonic Doppler flow probes were surgically affixed around the ventral aorta to monitor cardiovascular performance. After recovery from surgery replicated treatment groups were exposed to incremental increases in silt load (made from bentonite slurry), while cardiac output and its two components, heart rate and stroke volume, were measured simultaneously. Although both groups of rock bass responded significantly to low concentrations of silt (10 NTU), the response by riverine rock bass was rapidly extinguished by acclimation or physiological adjustment. Compensatory mechanisms to minimize cardiac (and respiratory) disruption attributable to increases in suspended silt appear to be inherent in rock bass of riverine origin. These fish appear to fully compensate for interference in gas exchange at the gill surfaces 60 min after initial exposure. In contrast, individual lacustrine rock bass were highly variable in their response to elevated silt concentrations. Changes in stroke volume and cardiac output suggested no clear compensatory mechanism or strategy to cope with increased silt levels.     

Effects of urbanization on the population structure of freshwater turtles across the United States

Landscape‐scale alterations that accompany urbanization may negatively affect the population structure of wildlife species such as freshwater turtles. Changes to nesting sites and higher mortality rates due to vehicular collisions and increased predator populations may particularly affect immature turtles and mature female turtles. We hypothesized that the proportions of adult female and immature turtles in a population will negatively correlate with landscape urbanization. As a collaborative effort of the Ecological Research as Education Network (EREN), we sampled freshwater turtle populations in 11 states across the central and eastern United States. Contrary to expectations, we found a significant positive relationship between proportions of mature female painted turtles (Chrysemys picta) and urbanization. We did not detect a relationship between urbanization and proportions of immature turtles. Urbanization may alter the thermal environment of nesting sites such that more females are produced as urbanization increases. Our approach of creating a collaborative network of scientists and students at undergraduate institutions proved valuable in terms of testing our hypothesis over a large spatial scale while also allowing students to gain hands‐on experience in conservation science.     

Value of information for climate observing systems

The Interagency Working Group Memo on the social cost of carbon is used to compute the value of information (VOI) of climate observing systems. A generic decision context is posited in which society switches from a business as usual (BAU) emissions path to a reduced emissions path upon achieving sufficient confidence that a trigger variable exceeds a stipulated critical value. Using assessments of natural variability and uncertainty of measuring instruments, it is possible to compute the time at which the required confidence would be reached under the current and under a new observing system, if indeed the critical value is reached. Economic damages (worldwide) from carbon emissions are computed with an integrated assessment model. The more accurate observing system acquires the required confidence earlier and switches sooner to the reduced emissions path, thereby avoiding more damages which would otherwise be incurred by BAU emissions. The difference in expected net present value of averted damages under the two observing systems is the VOI of the new observing system relative to the existing system. As illustration, the VOI for the proposed space-borne CLARREO system relative to current space-borne systems is computed. Depending on details of the decision context, the VOI ranges from 2 to 30 trillion US dollars.     

A multi-criteria decision analysis assessment of waste paper management options

The use of Multi-criteria Decision Analysis (MCDA) was investigated in an exercise using a panel of local residents and stakeholders to assess the options for managing waste paper on the Isle of Wight. Seven recycling, recovery and disposal options were considered by the panel who evaluated each option against seven environmental, financial and social criteria. The panel preferred options where the waste was managed on the island with gasification and recycling achieving the highest scores. Exporting the waste to the English mainland for incineration or landfill proved to be the least preferred options. This research has demonstrated that MCDA is an effective way of involving community groups in waste management decision making.     

Stream transport of herbicides and metabolites in a tile-drained, agricultural watershed

The occurrence of metabolites of many commonly used herbicides in streams has not been studied extensively in tile-drained watersheds. We collected water samples throughout the Upper Embarras River watershed [92% corn, Zea mays L., and soybean, Glycine max (L.) Merr.] in east-central Illinois from March 1999 through September 2000 to study the occurrence of atrazine (2-chloro-4-ethylamino-6-isopropylamino-s-triazine), metolachlor 12-chloro-N-(2-ethyl-6-methylphenyl)-N-(methoxy-1-methylethyl) acetamide], alachlor [2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl) acetamide], acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl) acetamide], and their metabolites. River water samples were collected from three subwatersheds of varying tile density (2.8-5.3 km tile km(-2)) and from the outlet (United States Geological Survey [USGS] gage site). Near-record-low totals for stream flow occurred during the study, and nearly all flow was from tiles. Concentrations of atrazine at the USGS gage site peaked at 15 and 17 microg L(-1) in 1999 and 2000, respectively, and metolachlor at 2.7 and 3.2 microg L(-1); this was during the first significant flow event following herbicide applications. Metabolites of the chloroacetanilide herbicides were detected more often than the parent compounds (evaluated during May to July each year, when tiles were flowing), with metolachlor ethanesulfonic acid [2-[(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxoethanesulfonic acid] detected most often (> 90% from all sites), and metolachlor oxanilic acid [2-[(2-ethyl-6-methylphenyl)(2-methoxy-1-methylethyl)amino]-2-oxoacetic acid] second (40-100% of samples at the four sites). When summed, the median concentration of the three chloroacetanilide parent compounds (acetochlor, alachlor, and metolachlor) at the USGS gage site was 3.4 microg L(-1), whereas it was 4.3 microg L(-1) for the six metabolites. These data confirm the importance of studying chloroacetanilide metabolites, along with parent compounds, in tile-drained watersheds.     

Distribution of trace element pollutants in a contaminated ecosystem established on metalliferous fluorspar tailings. 3: fluoride

High total soil fluoride (10 000 microg g(-1)) in the metalliferous fluorspar tailings was reflected by elevated concentrations in standing live vegetation (300-1000 microg g(-1)); plant roots (c. 6000 microg g(-1)); plant litter (c. 4000 microg g(-1)); total body concentrations of invertebrates (400-4000 microg g(-1)) and the small mammals Microtus agrestis (120-360 microg g(-1)) and Sorex araneus (140-250 microg g(-1)). Seasonal changes in the standing live vegetation and the availability of soil fluoride to plants are discussed. Seasonal changes in total body concentrations of the small mammals were related to the age structure of the populations as well as dietary levels. In the small mammals, the concentration ratios were < 0.5 at the tailings dam and > 1.1 at the control site, indicating that both species were able to regulate fluoride accumulation at the higher levels of intake. Soft tissue concentrations were, as expected, very low compared to the hard tissues but, still, were generally significantly higher at the tailings dam compared to the control site. Evidence of dental fluorosis was found in Microtus agrestis, but not Sorex araneus.     

SALINITY ISSUES AND WATER DEVELOPMENT IN THE GREEN RIVER BASIN,WYOMING1

Water development in the Green River Basin of Wyoming is projected to increase salinity downstream in the Green River and Colorado River, and thereby increase salinity costs to users of water from these two rivers. Despite these water quality and economic impacts to downstream water users, Wyoming will probably be able to develop its currently unused but allocated water supplies of the Green River Basin. The Colorado River Compact and Upper Colorado River Basin Compact are binding, and protect Wyoming's share of the Colorado River System waters for future use. The argument that water may be used to greater profit downstream is not sufficient to reduce Wyoming's allocation. In addition, the no-injury rule under the appropriation doctrine of law does not appear to protect prior downstream appropriations from increasing salinity in this case.     

Distribution of antimony in contaminated grassland: 2--Small mammals and invertebrates

Concentrations of antimony in invertebrates and small mammals from grasslands in the vicinity of an antimony smelter were significantly elevated compared to a control site. Higher concentrations of antimony were recorded in liver, lung and kidney tissue of herbivorous and insectivorous mammals from the contaminated sites. However, there is little evidence of bioaccumulation of antimony in food chains represented by the soil-vegetation-invertebrate-insectivore pathway of the grasslands, and little indication of significant accumulation by herbivorous mammals despite marked contamination of their diet.     

Pre-Colombian Mercury Pollution Associated with the Smelting of Argentiferous Ores in the Bolivian Andes

The development of the mercury (Hg) amalgamation process in the mid-sixteenth century triggered the onset of large-scale Hg mining in both the Old and New Worlds. However, ancient Hg emissions associated with amalgamation and earlier mining efforts remain poorly constrained. Using a geochemical time-series generated from lake sediments near Cerro Rico de Potosí, once the world’s largest silver deposit, we demonstrate that pre-Colonial smelting of Andean silver ores generated substantial Hg emissions as early as the twelfth century. Peak sediment Hg concentrations and fluxes are associated with smelting and exceed background values by approximately 20-fold and 22-fold, respectively. The sediment inventory of this early Hg pollution more than doubles that associated with extensive amalgamation following Spanish control of the mine (1574–1900 AD). Global measurements of [Hg] from economic ores sampled world-wide indicate that the phenomenon of Hg enrichment in non-ferrous ores is widespread. The results presented here imply that indigenous smelting constitutes a previously unrecognized source of early Hg pollution, given naturally elevated [Hg] in economic silver deposits.