Alternate Species Concepts as Bases for Determining Priority Conservation Areas

Abstract: Analysis of geographic concentrations of endemic taxa is often used to determine priorities for conservation action; nevertheless, assumptions inherent in the taxonomic authority list used as the basis for analysis are not always considered. We analyzed foci of avian endemism in Mexico under two alternate species concepts. Under the biological species concept, 101 bird species are endemic to Mexico and are concentrated in the mountains of the western and southern portions of the country. Under the phylogenetic species concept, however, total endemic species rises to 249, which are concentrated in the mountains and lowlands of western Mexico. Twenty-four narrow endemic biological species are concentrated on offshore islands, but 97 narrow endemic phylogenetic species show a concentration in the Transvolcanic Belt of the mainland and on several offshore islands. Our study demonstrates that conservation priorities based on concentrations of endemic taxa depend critically on the particular taxonomic authority employed and that biodiversity evaluations need to be developed in collaboration or consultation with practicing systematic specialists.     

Estuarine Vegetated Habitats as Corridors for Predator Movements

Abstract: The spatial proximity of one habitat to another can strongly influence population and community dynamics. We investigated whether the proximity of intertidal oyster reefs to vegetated estuarine habitats, salt marshes, and seagrass beds, affects the abundance and community structure of benthic macroinvertebrates on reefs and predator-prey interactions between mobile predators and bivalves living on reefs. Benthic macroinvertebrate abundance was highest on reefs spatially separated from salt marshes. Macroinvertebrate species richness was highest on reefs separated from both salt marshes and seagrass beds. Comparisons of predation on juvenile bivalves transplanted to reefs for 7–12 days indicated that survivorship of clams was greatest on reefs spatially separated from both salt marshes and seagrass beds, whereas reef proximity to vegetated habitats did not affect the survivorship of oysters. The foraging behavior of blue crabs may explain patterns of macroinvertebrate abundance and clam survivorship among reefs with different proximity to vegetated habitats. In experiments conducted in 30-m² field enclosures, blue crabs had higher predation rates on hard clams transplanted onto artificial reefs adjacent to salt marshes or seagrass beds than on reefs separated from both habitats by unvegetated sand bottom. Thus, vegetated habitats appeared to act as corridors by facilitating the access of blue crabs to oyster reefs and enhancing the intensity of blue crab predation. Such an understanding of the effects of landscape characteristics of estuarine habitats on their value as habitats for estuarine organisms can be used to predict the consequences of habitat fragmentation on ecosystem function and to improve strategies for habitat and species conservation and restoration.     

Chromium accumulation,transport and toxicity in plants∗

The predominant pathway for human exposure to chromium in non‐occupationally exposed individuals is via food with a daily intake of around 30–100 μgd^–1, with vegetables providing a major contribution. Unlike reports of chromium essentiality to man and animals, plants appear not to require chromium in spite of some early reports of a stimulatory growth effect.

Most reports on chromium in plants have been concerned with their growth on soils amended with sewage sludge, pF‐ash, tannery waste, or on ultra basic soils, which contain extreme concentrations of the element. Experimental studies with plants grown in hydroponic solution have often been undertaken at unrealistically high concentrations to examine the uptake of chromium in various forms, either as CrIII or CrVI at different pHs. In most cases, reports on chromium in plants deal with element concentrations and plant/soil relationships rather than detailed biochemical and physiological processes.

In general, chromium is largely retained in the roots of plants, although the oxidation state of chromium, pH, presence of humates and fulvates and plant species, affect plant uptake and transport. Leaves usually contain higher concentrations than grains. The uptake of CrIII is largely a passive process, whereas CrVI uptake is a metabolically mediated process via the sulphate pathway and is thus readily transported around the plant. The presence of a compound similar to trioxalate CrIII has been recorded while little chromium has been reported to be associated with cell organelles or soluble proteins.     

Behavioral consequences of exotic host plant adoption and the differing roles of male harassment on female movement in two checkerspot butterflies

Herbivorous insects may evolve convergent behaviors when independent adoption of a shared novel host plant places populations in environmental conditions that diverge from the ancestral state. We investigated the behavioral consequences of adopting Plantago lanceolata, an exotic species to North America, in populations of Euphydryas p. phaeton and Euphydryas editha taylori, on the east and west coasts of North America. Activity budgets and short-term movements suggested that innate species tendencies exert a greater impact on behavior than adoption of the same exotic host plant. However, female E. phaeton from a Plantago-dependent population spent more time inspecting host plants than females from a population dependent on the native host plant, Chelone glabra. Both checkerspot species had similar diffusion coefficients (D) regardless of host plant association. But, E. e. taylori step-lengths appeared bimodal and power law distributed while E. phaeton step-lengths were unimodal and best fit by an exponential distribution. We attribute this bimodal step-length distribution to the persistent harassment of courting males which induces a “long-distance” evasive flight in otherwise sedentary E. e. taylori females. In contrast, the longer distance step-lengths of E. phaeton were associated with the inspection of oviposition plants. These two checkerspot species appear to move greater distances across the reproductive landscape with contrasting motivational states that could lead to either intimate mapping (E. phaeton) or coarse mapping (E. e. taylori) of host resources.     

Capital structure and asset utilization: the case of resource intensive industries

This research studies the relationship between the capital structure of a firm and its asset utilization rate in resource intensive industries. We study this issue from both private and public policy perspectives. From a private perspective, it's conceivable that a positive relationship may exist because a company is trying to increase its use of debt to effect a more efficient utilization of its assets. However, from a public policy perspective, finding a positive relationship between asset utilization and debt levels in natural resource sensitive industries may signal a sub-optimal exploitation of natural resources when debt levels rise. This research examines measures of leverage and asset utilization in firms from the mining, oil, and timber industries to determine whether the behavior alleged in the PALCO/MAXXAM case (an increased cutting rate to pay off junk bond financing) has been observed more systematically. We observe a positive relationship between leverage and asset utilization in all three industries when leverage is calculated using book value measures. When market value measures are used, this positive relationship no longer holds in the mining industry. Possible explanations for these results are offered.     

Patterns of Spatial Autocorrelation in Stream Water Chemistry

Geostatistical models are typically based on symmetric straight-line distance, which fails to represent the spatial configuration, connectivity, directionality, and relative position of sites in a stream network. Freshwater ecologists have explored spatial patterns in stream networks using hydrologic distance measures and new geostatistical methodologies have recently been developed that enable directional hydrologic distance measures to be considered. The purpose of this study was to quantify patterns of spatial correlation in stream water chemistry using three distance measures: straight-line distance, symmetric hydrologic distance, and weighted asymmetric hydrologic distance. We used a dataset collected in Maryland, USA to develop both general linear models and geostatistical models (based on the three distance measures) for acid neutralizing capacity, conductivity, pH, nitrate, sulfate, temperature, dissolved oxygen, and dissolved organic carbon. The spatial AICC methodology allowed us to fit the autocorrelation and covariate parameters simultaneously and to select the model with the most support in the data. We used the universal kriging algorithm to generate geostatistical model predictions. We found that spatial correlation exists in stream chemistry data at a relatively coarse scale and that geostatistical models consistently improved the accuracy of model predictions. More than one distance measure performed well for most chemical response variables, but straight-line distance appears to be the most suitable distance measure for regional geostatistical modeling. It may be necessary to develop new survey designs that more fully capture spatial correlation at a variety of scales to improve the use of weighted asymmetric hydrologic distance measures in regional geostatistical models.     

Integrated approach to PCE‐impacted site characterization,site management,and enhanced bioremediation

Tetrachloroethene (PCE)‐ and trichloroethene (TCE)‐impacted sites pose significant challenges even when site characterization activities indicate that biodegradation has occurred naturally. Although site‐specific, regulatory, and economic factors play roles in the remedy‐selection process, the application of molecular biological tools to the bioremediation field has streamlined the assessment of remedial alternatives and allowed for detailed evaluation of the chosen remedial technology. The case study described here was performed at a PCE‐impacted site at which reductive dechlorination of PCE and TCE had led to accumulation of cis‐dichlorethene (cis‐DCE) with concentrations ranging from approximately 10 to 100 mg/L. Bio‐Trap® samplers and quantitative polymerase chain reaction (qPCR) enumeration of Dehalococcoides spp. were used to evaluate three remedial options: monitored natural attenuation, biostimulation with HRC®, and biostimulation with HRC‐S®. Dehalococcoides populations in HRC‐S‐amended Bio‐Traps deployed in impacted wells were on the order of 10³ to 10⁴ cells/bead but were below detection limits in most unamended and HRC‐amended Bio‐Traps. Thus the in situ Bio‐Trap study identified biostimulation with HRC‐S as the recommended approach, which was further evaluated with a pilot study. After the pilot HRC‐S injection, Dehalococcoides populations increased to 10⁶ to 10⁷ cells/bead, and concentrations of cis‐DCE and vinyl chloride decreased with concurrent ethene production. Based on these results, a full‐scale HRC‐S injection was designed and implemented at the site. As with the pilot study, full‐scale HRC‐S injection promoted growth of Dehalococcoides spp. and stimulated reductive dechlorination of the daughter products cis‐DCE and vinyl chloride. © 2008 Wiley Periodicals, Inc.     

Inorganic pigments made from the recycling of coal mine drainage treatment sludge

Continuous industrial development increases energy consumption and, consequently, the consumption of fossil fuels. Coal mineral has been used in Brazil as a solid fuel for thermoelectric generators for several years. However, coal exploitation affects the environment intensely, mainly because Brazilian coal contains excess ash and pyrite (iron disulfide). According to the local coal industry syndicate, the average annual coal run per mine is 6 million ton/year; 3.5 million ton/year are rejected and disposed of in landfills. Besides pyrite, Brazilian coal contains Mn, Fe, Cu, Pb, Zn, Ge, Se, and Co. Additionally, the water used for coal beneficiation causes pyrite oxidation, forming an acid mine drainage (AMD). This drainage solubilizes the metals, transporting them into the environment, making treatment a requirement. This work deals with the use of sedimented residue from treated coal mine drainage sludge to obtain inorganic pigments that could be used in the ceramic industry. The residue was dried, ground and calcined ( approximately 1250 degrees C). The calcined pigment was then micronized (D(50) approximately 2mum). Chemical (XRF), thermal (DTA/TG), particle size (laser), and mineralogical (XRD) analyses were carried out on the residue. After calcination and micronization, mineralogical analyses (XRD) were used to determine the pigment structure at 1250 degrees C. Finally, the pigments were mixed with transparent glaze and fired in a laboratory roller kiln (1130 degrees C, 5min). The results were promising, showing that brown colors can be obtained with pigments made by residues.     

Human Influences on Water Quality in Great Lakes Coastal Wetlands

A better understanding of relationships between human activities and water chemistry is needed to identify and manage sources of anthropogenic stress in Great Lakes coastal wetlands. The objective of the study described in this article was to characterize relationships between water chemistry and multiple classes of human activity (agriculture, population and development, point source pollution, and atmospheric deposition). We also evaluated the influence of geomorphology and biogeographic factors on stressor-water quality relationships. We collected water chemistry data from 98 coastal wetlands distributed along the United States shoreline of the Laurentian Great Lakes and GIS-based stressor data from the associated drainage basin to examine stressor-water quality relationships. The sampling captured broad ranges (1.5–2 orders of magnitude) in total phosphorus (TP), total nitrogen (TN), dissolved inorganic nitrogen (DIN), total suspended solids (TSS), chlorophyll a (Chl a), and chloride; concentrations were strongly correlated with stressor metrics. Hierarchical partitioning and all-subsets regression analyses were used to evaluate the independent influence of different stressor classes on water quality and to identify best predictive models. Results showed that all categories of stress influenced water quality and that the relative influence of different classes of disturbance varied among water quality parameters. Chloride exhibited the strongest relationships with stressors followed in order by TN, Chl a, TP, TSS, and DIN. In general, coarse scale classification of wetlands by morphology (three wetland classes: riverine, protected, open coastal) and biogeography (two ecoprovinces: Eastern Broadleaf Forest [EBF] and Laurentian Mixed Forest [LMF]) did not improve predictive models. This study provides strong evidence of the link between water chemistry and human stress in Great Lakes coastal wetlands and can be used to inform management efforts to improve water quality in Great Lakes coastal ecosystems.