Recent Changes in Soil Total Phosphorus in the Everglades: Water Conservation Area 3

We assessed recent changes in the distribution of soil total phosphorus (TP) in Water Conservation Area 3 (WCA-3) of the Everglades. Soil cores were collected in 1992 and 2003 at 176 sites. To reflect hydrologic boundaries within the system, WCA-3 was divided into three zones (3AN, 3AS, and 3B). Total P was mapped on both a mass (TPm) and a volumetric basis (TPv) to determine if spatial distributions varied depending on the choice of units. Interpolated maps for both years showed that the highest levels of TPm were located in 3AN and in boundary areas of all zones that received surface water inputs of P from canals. Increases in TPm were greatest in central 3AN in an area adjacent to the Miami Canal that received inputs from a water control structure. Interpolated maps for TPv illustrated that a hotspot present in 1992 had disappeared by 2003. The highest levels of TPv in 2003 were located in northwestern 3AN, a region of WCA-3 that has been chronically overdrained and burned in 1999. From 1992 to 2003, increases in TPm were observed for 53% of the area of WCA-3, while only 16% of WCA-3 exhibited increases in TPv. In 1992, approximately 21% of WCA-3 had TPm concentrations in the 0–10 cm layer >500 mg kg⁻¹, indicating P enrichment beyond historic levels. Eleven years later, 30% of the area of WCA-3 had TPm >500 mg kg⁻¹. This indicated that during this period, the area of WCA-3 with enriched TPm concentrations increased about one % year⁻¹.     

Effects of Habitat Size and Patch Isolation on Reproductive Success of the Serpentine Morning Glory

Abstract: We examined the effects of habitat area and patch isolation on reproductive success in serpentine morning glory ( Calystegia collina [Convolvulaceae]), a primarily self-incompatible clonal plant endemic to serpentine outcrops in northern California's coast ranges. Within a 4000-km ² region, we compared the reproductive success of C. collina on 16 small (<5 ha) and 7 large ( >300 ha) outcrops. Flower and fruit production were significantly higher on large serpentine outcrops than on small outcrops. Fruit production also was positively correlated with the soil's ratio of calcium to magnesium. Successful pollination was positively affected by flower density and the number of other flowering patches within 100 m of a C. collina patch. The number of nearby flowering patches was considerably higher on large than on small outcrops. Flowers on large outcrops did not receive significantly more bee visitors than flowers on small outcrops, suggesting that pollination success is related to the quality rather than the quantity of pollen deposited. Fruit production by plants on both small and large outcrops was enhanced by the experimental addition of pollen from other patches, but not by the addition of pollen from the same patch. These findings demonstrate that the size of habitat may have strong effects on the reproductive success of locally endemic plants by enhancing opportunities for successful sexual reproduction. They also warn against the presumption that naturally patchy plant species are invulnerable to the effects of habitat fragmentation.     

Patterns of Genetic Diversity in Remaining Giant Panda Populations

Abstract: The giant panda ( Ailuropoda melanoleuca ) is among the more familiar symbols of species conservation. The protection of giant panda populations has been aided recently by the establishment of more and better-managed reserves in existing panda habitat located in six mountain ranges in western China. These remaining populations are becoming increasingly isolated from one another, however, leading to the concern that historic patterns of gene flow will be disrupted and that reduced population sizes will lead to diminished genetic variability. We analyzed four categories of molecular genetic markers (mtDNA restriction-fragment-length polymorphisms [RFLP], mtDNA control region sequences, nuclear multilocus DNA fingerprints, and microsatellite size variation) in giant pandas from three mountain populations (Qionglai, Minshan, and Qinling) to assess current levels of genetic diversity and to detect evidence of historic population subdivisions. The three populations had moderate levels of genetic diversity compared with similarly studied carnivores for all four gene measures, with a slight but consistent reduction in variability apparent in the smaller Qinling population. That population also showed significant differentiation consistent with its isolation since historic times. From a strictly genetic perspective, the giant panda species and the three populations look promising insofar as they have retained a large amount of genetic diversity in each population, although evidence of recent population reduction—likely from habitat loss—is apparent. Ecological management to increase habitat, population expansion, and gene flow would seem an effective strategy to stabilize the decline of this endangered species.     

Humanitarian War: A New Consensus?

The NATO bombing operation Allied Force against Yugoslavia in March-June 1999 represents the final disappearance of the narrowing divide between humanitarianism and politics: a war initiated and justified on humanitarian grounds. Although unlikely to be repeated any time soon, the Kosovo case appears to have cemented an ideological shift on the international right and even necessity of sing military force to protect civilians within sovereign states. Rather than humanitarians acknowledging the political context and consequences of their work, however, the case suggests the embrace of humanitarian principles of universality and neutrality by military organisations. This article discusses some consequences of the new consensus: neglect of the political context (both local and foreign) of such operations, interaction between the operational dynamics of relief operations and the logic of war and the political consequences of using the humanitarian legitimation and mission in such cases.     

Trophic dynamics of U, Ni, Hg and other contaminants of potential concern on the Department of Energy’s Savannah River Site

The Department of Energy’s Savannah River Site is a former nuclear weapon material production and current research facility located in South Carolina, USA. Wastewater discharges from a fuel and nuclear reactor target manufacturing facility released depleted and natural U, as well as other metals into the Tims Branch-Steed Pond water system. We investigated the current dynamics of this system for the purposes of environmental monitoring and assessment by examining metal concentrations, bioavailability, and trophic transfer of contaminants in seven ponds. Biofilm, detritus, and Anuran and Anisopteran larvae were collected and analyzed for stable isotopes (δ ¹⁵N, δ ¹³C) and contaminants of potential concern (COPC) with a focus on Ni, U, and Hg, to examine metal mobility. Highest levels of Ni and U were found in biofilms U (147 and 332 mg kg^?1 DW, respectively), while highest Hg levels were found in tadpoles (1.1 mg kg^?1 DW). We found intraspecific biomagnification of COPCs as expressed through stable isotope analysis. Biofilms were the best indicators for contamination and Anuran larvae with the digestive tract removed were the best indicators of the specific bioavailability of the focal metals. Monitoring data showed that baseline δ ¹⁵N values differed between ponds, but within a pond, values were stable throughout tadpole Gosner stage, strengthening the case to use this species for monitoring purposes. It is likely that there still is risk to ecosystem integrity as COPC metals are being assimilated into lower trophic organisms and even low levels of this mixture has shown to produce deleterious effects to some wildlife species.     

Food crop accumulation and bioavailability assessment for antimony (Sb) compared with arsenic (As) in contaminated soils

Field samples and a 9-week glasshouse growth trial were used to investigate the accumulation of mining derived arsenic (As) and antimony (Sb) in vegetable crops growing on the Macleay River Floodplain in Northern New South Wales, Australia. The soils were also extracted using EDTA to assess the potential for this extractant to be used as a predictor of As and Sb uptake in vegetables, and a simplified bioaccessibility extraction test (SBET) to understand potential for uptake in the human gut with soil ingestion. Metalloids were not detected in any field vegetables sampled. Antimony was not detected in the growth trial vegetable crops over the 9-week greenhouse trial. Arsenic accumulation in edible vegetable parts was <10 % total soil-borne As with concentrations less than the current Australian maximum residue concentration for cereals. The results indicate that risk of exposure through short-term vegetable crops is low. The data also demonstrate that uptake pathways for Sb and As in the vegetables were different with uptake strongly impacted by soil properties. A fraction of soil-borne metalloid was soluble in the different soils resulting in Sb soil solution concentration (10.75?±?0.52 μg L^–1) that could present concern for contamination of water resources. EDTA proved a poor predictor of As and Sb phytoavailability. Oral bioaccessibility, as measured by SBET, was <7 % for total As and <3 % total Sb which is important to consider when estimating the real risk from soil borne As and Sb in the floodplain environment.     

Using Expert and Non-expert Models of Climate Change to Enhance Communication

Climate change is a significant global risk that is predicted to be particularly devastating to coastal communities. Climate change adaptation and mitigation have been hindered by many factors, including psychological barriers, ineffective outreach and communication, and knowledge gaps. This qualitative study compares an expert model of climate change risks to county administrators' “mental” models of climate change and related coastal environmental hazards in Crystal River, Florida, USA. There were 24 common nodes in the expert and the combined non-expert models, mainly related to hurricanes, property damage, and economic concerns. Seven nodes mentioned by non-experts fit within, but were not a part of, the expert model, primarily related to ecological concerns about water quality. The findings suggest that effective climate outreach and communication could focus on compatible parts of the models and incorporate local concerns to find less controversial ways to discuss climate-related hazards.     

Ecological commonalities among pelagic fishes: comparison of freshwater ciscoes and marine herring and sprat

Systematic comparisons of the ecology between functionally similar fish species from freshwater and marine aquatic systems are surprisingly rare. Here, we discuss commonalities and differences in evolutionary history, population genetics, reproduction and life history, ecological interactions, behavioural ecology and physiological ecology of temperate and Arctic freshwater coregonids (vendace and ciscoes, Coregonus spp.) and marine clupeids (herring, Clupea harengus, and sprat, Sprattus sprattus). We further elucidate potential effects of climate warming on these groups of fish based on the ecological features of coregonids and clupeids documented in the previous parts of the review. These freshwater and marine fishes share a surprisingly high number of similarities. Both groups are relatively short-lived, pelagic planktivorous fishes. The genetic differentiation of local populations is weak and seems to be in part correlated to an astonishing variability of spawning times. The discrete thermal window of each species influences habitat use, diel vertical migrations and supposedly also life history variations. Complex life cycles and preference for cool or cold water make all species vulnerable to the effects of global warming. It is suggested that future research on the functional interdependence between spawning time, life history characteristics, thermal windows and genetic differentiation may profit from a systematic comparison of the patterns found in either coregonids or clupeids.     

The impact of technology characteristics and job control on worker mental health

Recent research suggests that the occurrence of operational problems in advanced manufacturing technology (AMT) places stressful demands on operators. Applying Karasek's demand–control model, we predict that two properties of operational problems, namely technological uncertainty and abstractness, interact with timing and method control to predict operator strain. The results failed to confirm ordinal effects for timing or method control, but showed a dis-ordinal (crossover) interaction for timing control. While these findings provide little support for the demand–control model, they suggest that two new processes, namely ‘traction–distraction’ and ‘passivity–challenge’, are critical to understanding the nature of the relationship between operational problems and operator strain in AMT systems. We describe these processes and examine the implications for future research. © 1997 John Wiley & Sons, Ltd.