Mapping Grazing-Induced Degradation in a Semi-Arid Environment: A Rapid and Cost Effective Approach for Assessment and Monitoring

Improved techniques for measuring and monitoring the state of biodiversity are required for reporting on national obligations to international and regional conservation institutions. Measuring the extent of grazing-related degradation in semi-arid ecosystems has proved difficult. Here we present an accurate and cost-effective method for doing this, and apply it in a South African semi-arid region that forms part of a globally significant biodiversity hotspot. We grouped structurally and functionally similar vegetation units, which were expert-mapped at the 1:50,000 scale, into four habitat types, and developed habitat-specific degradation models. We quantified degradation into three categories, using differences between dry and wet season values of the Normalized Difference Vegetation Index (NDVI) for the three succulent karoo habitats, and the difference between maximum and mean NDVI values for the subtropical thicket habitat. Field evaluation revealed an accuracy of 86%. Overall, degradation was high: 24% of the study area was modeled as severely degraded, and only 9% as intact. Levels of degradation were highest for bottomland habitats that were most exposed to grazing impacts. In sharp contrast to our methods, a widely used, broad-scale and snapshot assessment of land cover in South Africa was only 33% accurate, and it considerably underestimated the extent of severely degraded habitat in the study area. While our approach requires a multidisciplinary team, and in particular expert knowledge on the characteristics and spatial delimitation of vegetation types, it is repeatable, rapid, and relatively inexpensive. Consequently, it holds great promise for monitoring and evaluation programs in semi-arid ecosystems, in Africa, and beyond.     

AQUATIC IMPACTS OF DEICING SALTS IN THE CENTRAL SIERRA NEVADA MOUNTAINS,CALIFORNIA1

ABSTRACT: The fate and effect of sodium chloride applied to Californian highways in the Lake Tahoe, Truckee River, and Yuba River watersheds were studied over a period of 14 months in 1974–75. Chloride levels in streams below major freeways were found to be elevated during the winter. The high chloride levels occurred after the application of salt to roads, decreasing as the time from application increases. Small lakes receiving runoff from major highways were also enriched with chloride. Several of these lakes displayed a temporary chemocline, which was sufficiently strong to stabilize a temperature inversion in one lake.     

Arsenic uptake and loss in the American oyster,Crassostrea virginica

In addition to a control Crassostrea virginica was treated with 3 and 5 g As kg^p-1 for 16 wks at ambient seawater salinity and temperature to determine the potential of C. virginica as an indicator of arsenic pollution. Prior to spawning, as much as 10.3±1.5, 12.7±2.7, and 14.1±3.7 g As g^p-1 dry weight were accumulated in the total soft parts of oysters after treatment with ambient (control), 3 and 5 g As kg^-1, respectively. Immediately after spawning, an increase in tissue arsenic concentration was observed in all treatments up to week 12, after which a decrease in tissue arsenic concentrations occurred despite continuous addition of arsenic to the seawater. During the uptake period, a significant inverse relationship existed between dry weight and tissue arsenic concentration, whereas a significant direct relationship was apparent between dry weight and tissue content. Arsenic concentration in the total soft parts is not significantly related to seawater arsenic concentration over the range of concentrations used in this study. In all three treatments, arsenic uptake as concentration (g g^p-1) is not a significant linear function of time. Weight loss was significant but gradual during the first 16 wks of treatment and did not change significantly during the depuration period (wks 17–25). Tissue arsenic concentrations increased significantly in oysters from all three treatments during the depuration period. Generally, arsenic body burdens increased with increases in phytoplankton concentration and it appears that food contributes more to arsenic uptake than seawater arsenic concentrations. Since a relationship between tissue arsenic concentration and seawater arsenic concentration does not appear to exist, C. virginica would not be a good biological indicator of arsenic concentration in its environment.     

Application of in-situ bioremediation to a gasoline spill in fractured bedrock

After achieving remediation goals during only thirty-two months of operation, the first full-scale in-situ bioremediation (ISB) system in the state of Missouri was shut down in 1990. In addition to ISB, the system included a combination of soil venting and air stripping to remediate subsurface gasoline contamination at a large manufacturing facility. More than 84,000 pounds of gasoline were degraded or removed from the fractured limestone bedrock aquifer and overburden materials. The successful application of ISB in this complex geologic environment and the fact that this was the first such system to complete remediation in Missouri make this system unique.     

A COLORIMETRIC METHOD FOR THE DETERMINATION OF TRACE COPPER CONCENTRATIONS IN WATER1

Trace quantities of copper (II) ion can be found in natural water as waste products from industrial, mining, and agricultural operations. Because low concentrations of copper can be toxic to plant life, many workers have devised methods of analysis for this metal in water. These methods require expensive equipment and skilled technicians. The described study illustrates a simple method in which copper (II) ion is concentrated by a batch ion exchange technique and estimated colorimetrically after formation of the blue triethylenetetramine complex. Using the visible absorption peak of the complex at 600 nm it was possible to obtain accurate estimations of original copper concentrations in the range 0.5-3 ppm. Using the complex absorption peak at 260 nm in the ultra-violet region of the spectrum increased the sensitivity by a factor of twenty. Because of the dependence of the complex formation reaction on solution acidity it is possible to optimize conditions for the detection of copper (II) in the presence of other metal ions. This type of method, which could be extended to the analysis of other metal ions, could be performed by a relatively unskilled technician under field conditions.     

Altered c-Fos expression demonstrates neuronal stress in mummichog, <Emphasis Type="Italic">Fundulus heteroclitus</Emphasis>, exposed to <Emphasis Type="Italic">Pfiesteria shumwayae</Emphasis> and <Emphasis Type="Italic">Chaetoceros concavicornis</Emphasis>

To better understand sublethal effects of harmful algal blooms (HABs) on fish, mummichog, Fundulus heteroclitus (L.), were exposed in the laboratory to varying, environmentally relevant densities of Pfiesteria shumwayae (Glasgow et Burkholder, CCMP 2089, dinoflagellate) and Chaetoceros concavicornis (Mangin, CCMP 169, diatom). Two experiments were conducted during the spring of 2003 and 2004 to quantitatively examine the effects of acute (2 h) P. shumwayae and C. concavicornis algal exposure on mummichog brain activity using c-Fos expression as a marker of altered neuronal activity. Brains from HAB-exposed fish were removed, sectioned, and stained using immunocytochemistry prior to quantifying neuronal c-Fos expression. Fish exposed to P. shumwayae and C. concavicornis showed increased c-Fos expression compared to unexposed control fish. A significant dose-response relationship was observed, with increased labeling in brains of fish exposed to higher cell densities for both HAB species tested (P ≤ 0.01). Increased labeling was found in the telencephalon, optic lobes, midbrain, and portions of the medulla. The greatest increases in expression were observed in the telencephalon of P. shumwayae-exposed fish, and in the telencephalon and optic lobes of C. concavicornis-exposed fish (P ≤ 0.01). These increases in c-Fos expression are consistent with other physical and chemical stress exposures observed in fish. Neuronal stress, evidenced by c-Fos expression, demonstrates a sublethal effect of exposure and changes in brain activity in fish exposed to HAB species.