Effects of metals on condition and reproductive output of the smooth toadfish in Sydney estuaries, south-eastern Australia

This study determined the condition and reproductive output of a common estuarine toadfish, Tetractenos glaber, in two metal contaminated and two reference estuaries near Sydney, Australia. Female toadfish from metal contaminated estuaries were smaller and younger than in reference estuaries; however, it could not be resolved whether these differences were due to direct effects of metal contamination or differences in nutritional value of prey. Lipid content in liver and gonad tissues was inversely related with levels of As, Pb, Cd and Co in sediment. In contrast, protein content in liver, gonad and muscle tissues was positively related to sediment levels of Ni and Co. Increased levels of Pb in gonads were associated with decreased oocyte diameter and density. This suggests a reduction in egg size and fecundity, which ultimately may lead to a decline in female reproductive output. Changes in fish health and reproduction caused by chemical pollutants may alter fish population and community structure.     

Differences in stress tolerance and brood size between a non-indigenous and an indigenous gammarid in the northern Baltic Sea

Differences in stress tolerance and reproductive traits may drive the competitive hierarchy between non-indigenous and indigenous species and turn the former ones into successful invaders. In the northern Baltic Sea, the non-indigenous Gammarus tigrinus is a recent invader of littoral ecosystems and now occupies comparable ecological niches as the indigenous G. zaddachi. In laboratory experiments on specimens collected between June and August 2009 around Tvärminne in southern Finland (59°50′N/23°15′E), the tolerances towards heat stress and hypoxia were determined for the two species using lethal time, LT₅₀, as response variable. The brood size of the two species was also studied and some observations were made on maturation of juveniles. Gammarus tigrinus was more resistant to hypoxia and survived at higher temperatures than G. zaddachi. Brood size was also greater in G. tigrinus than in G. zaddachi and G. tigrinus matured at a smaller size and earlier than G. zaddachi. Hence, there are clear competitive advantages for the non-indigenous G. tigrinus compared to the indigenous G. zaddachi, and these may be further strengthened through ongoing environmental changes related to increased eutrophication and a warming climate in the Baltic Sea region.     

Persistence of testosterone and 17beta-estradiol in soils receiving swine manure or municipal biosolids

Natural and synthetic steroidal hormones can be carried to agricultural soil through fertilization with municipal biosolids, livestock manure, or poultry manure. The persistence and pathways of dissipation of [4-(14)C]-testosterone and of [4-(14)C]-17beta-estradiol in organic-amended soils were investigated using laboratory microcosms. Testosterone dissipation was investigated over a range of amendment concentrations, temperatures, and soil types. Under all conditions the parent compound and transformation products were dissipated within a few days. Addition of swine manure slurry to soil hastened the transformation of testosterone and 17beta-estradiol to the corresponding less hormonally active ketones, 4-androstene-3,17-dione and estrone. Two other testosterone transformation products, 5alpha-androstan-3,17-dione and 1,4-androstadiene-3,17-dione, were also detected. Experiments with sterilized soil and sterilized swine manure slurry suggested that the transformation of (14)C-labeled hormonal parent compounds was mainly caused by microorganisms in manure slurry, while mineralization of the hormones to (14)CO(2) required viable soil microorganisms. Organic amendments transiently inhibited the mineralization of [4-(14)C]-testosterone, perhaps by inhibiting soil microorganisms, or by enhancing sorption and reducing the bioavailability of testosterone or transformation products. Overall, organic amendments influenced the pathways and kinetics of testosterone and estradiol dissipation, but did not increase their persistence.     

PATTERN OF GROUND-WATER LEVEL DECLINE IN THE HIGH PLAINS AQUIFER NEBRASKA1

ABSTRACT: Ground-water level decline patterns in parts of Nebraska conform to the circular island concept of Bredehoeft et al. (1982), which indicates how water is derived by wells developed in a circular island. If elongated, the center of the island corresponds to a regional ground-water divide while the shoreline corresponds to a regional river. In both versions, ground-water table elevation is a function of recharge and transmissivity. A dynamic equilibrium exists such that the gradient of the water table will convey all recharge to discharge areas. Withdrawals of ground water result initially in mining, with a new equilibrium attained when pumping equals capture. During early development, capture is an important source of water in discharge areas, while mining is more significant in recharge areas. The pattern observed in many areas shows the greatest ground-water level decline in the vicinity of ground-water divides and the steepest gradient near regional rivers. A similar pattern has been observed adjacent to the Arkansas River in south-central Kansas. Similar decline patterns can be modeled for a hypothetical ground-water basin. This is of major importance to water-resource managers because it dictates that management programs be applied to the entire hydrologic system.     

Predicting the multiple pathways of plant succession

Classical concepts view succession as a deterministic, mechanistic regeneration of the disturbed community, and thus have limited applicability to fire-prone ecosystems, A recently developed multiple pathway succession model appears to have more realism and applicability in frequently disturbed ecosystems. It includes a set of species-specific attributes that are vital to reproduction and survival, and permits variable succession pathways depending on the stand's age (and thus species composition) when disturbed. Examples from Australia and the northern Rocky Mountains (USA) are presented, as are approaches to refining and improving the model.     

Structuring cooperative behavior under the National Environmental Policy Act of the United States

A trend is presently under way to streamline the compliance requirements of the National Environmental Policy Act of the United States through cooperative assessment procedures. Since the law was enacted in 1970, however, participants in the assessment process have tended to settle disagreements by adversarial rather than cooperative means. This study focuses on a highly acclaimed environmental assessment procedure undertaken by the U.S. Steel Corporation for its proposed $4.0 billion Lakefront Steel Plant. Survey research data were gathered to measure the underlying management philosophy perceived by interorganizational representatives, who attended a series of Technical Team meetings designed to coordinate the assessment effort and to open communication channels. A social psychological scale of behavioral dimensions was adapted from Likert to define the composition and the extent of cooperation at these meetings. A newly constructed scale was used to measure the quantity and quality of representation by each of the major organizations involved. Informal interviews were conducted with project participants to obtain further insight into member interaction. Results indicate that democratic problem solving was in evidence but also suggest a preference by respondents for improved procedures. The paper outlines areas of concern voiced by respondents and offers the means for improving the operating procedures of similar interorganizational environmental assessments.     

Quantifying natural resource injuries and ecological service reductions: challenges and opportunities

The natural resource damage assessment (NRDA) provisions of the Comprehensive Environmental Response, Compensation, and Liability Act (CERCLA) and the Oil Pollution Act (OPA) are complex and have been difficult to implement. The complexity and difficulty in implementation arise both from the assessment procedures specified in agency NRDA guidance and from the limited ability of ecologists to quantify impacts of hazardous substances on natural resources. This paper explores the scientific aspects of NRDA implementation, and discusses conceptual and methodological relationships between NRDA and the much broader field of ecological risk assessment (ERA). We discuss three critical components of the NRDA assessment approach: measuring natural resource injuries and reductions in resource services; evaluating causality; and establishing baseline conditions. We identify (1) specific approaches drawn from ERA practice that could improve each of these components, and (2) research needs and institutional changes that may improve the ability of the NRDA process to achieve its stated objectives. We recommend the acceleration of the ongoing dialogue among NRDA practitioners from the Trustee and PRP communities as a first step toward resolving the procedural and technical deficiencies of the NRDA process.     

Garrett hardin: Dilemmas and taboos

Summary Garrett Hardin has written extensively about the biological, ecological and social impacts of various approaches to allocating natural resources. His work has been based largely upon the theory of the tragedy of the commons, population genetics and the application of biological principles to analogous social processes. He points out that policies that are morally appealing, because of their short-term benefits, may lead to disaster in the years ahead. His recommendations have stimulated considerable controversy and have been the object of moral criticism. They should not, however, be dismissed without careful consideration. Ralph H. Lutts is director of a natural history museum and an environmental education center. He is also adjunct assistant professor of environmental studies in the School of Natural Science of Hampshire College, Amherst, Massachusetts. His research interests are in environmental ethics and history.     

Managing bioremediation of a creosote‐contaminated superfund site by optimizing moisture and temperature in a biopile

Soil moisture content and temperature in a contaminated soil biopile equipped with immobilized microbe bioreactors (IMBRs) were optimized during ex situ bioremediation at a creosote‐contaminated Superfund site. Efficiency of remediation during warm summer months without soil‐temperature and moisture optimization was compared with that of cold winter months when corrective measures were applied. Significant reduction (35 percent) in total polycyclic aromatic hydrocarbons (PAHs) was observed, compared to 3.97 percent without corrective measures (p < 0.05). Kinetic rates (KRs) for total PAH removal were significantly enhanced from 3.93 to 50.95 mg/kg/day. KRs for removal of high molecular mass four‐to‐six‐ring PAHs were also significantly enhanced from 70.29 mg/kg/day to 97.45 mg/kg/day ( p < 0.05). Bioremediation of two‐ and three‐ring PAHs increased significantly from 15 percent to 40 percent. Benzo[a]pyrene toxicity equivalent mass (BaP_equiv) was significantly reduced by 48 percent with KR of 0.47 mg/kg/day as compared to 22 percent with KR of 0.14 mg/kg/day (p < 0.05). Soil moisture content was enhanced from 15.7 percent to 41.4 percent. © 2007 Wiley Periodicals, Inc.