BEHAVIORAL RESPONSES TO TWO ESTUARINE FISH SPECIES SUBJECTED TO BIS (tri-n-butyltin) OXIDE1

ABSTRACT: The objective of this investigation was to evaluate the avoidance responses of juvenile striped bass, Morone saxatilis and Atlantic menhaden, Brevoortia tyrannus to bis (tri-n-butyltin) oxide. An avoidance responses was exhibited by striped bass at a total organic tin concentration of 24.9 μg/L. Atlantic menhaden exhibited avoidance to total organic tin concentrations of 5.5 μg/L and greater. Atlantic menhaden are generally more sensitive to toxicants than striped bass; therefore, avoidance responses reported in this study are not surprising. It is highly likely that the concentrations of total organic tin that were avoided by the test species in this study were much higher than expected environmental concentrations. Ecologically significant hazards may occur due to potential effects that unperceived or non-avoided organotin concentrations may have on behavioral responses mediated by chemosensory systems.     

Socially cooperative choices: An approach to achieving resource sustainability in the coastal zone

Achieving resource sustainability, particularly in the coastal zone, is complicated by a variety of interdependencies and trade-offs between economic, social, and ecological variables. Although trade-offs between each of these variables are important, this paper emphasizes the social components of resource management. In this regard a distinction is made between individual and cooperative choices. Individual choices frequently are made from a shortterm, self-interested perspective, whereas cooperative choices are made from a long-term, community and resource-sustainability perspective. Typically, when presented with a spectrum of resource management decisions, individuals have a tendency to act in a self-interested manner. Thus, cooperative benefits, such as reduced conflict and improved resource certainty, are not realized. An overview of selected aspects of social dilemma theory suggests that socially cooperative choice outcomes are attainable in coastal zone management by integrating structural and behavioral solutions in resource use decision making. Three barriers to successful integration of structural and behavioral solutions are identified as self-interest, mistrust, and variable perceptions of resource amenities. Examples from coastal zone management indicate that these barriers may be overcome using approaches such as scopereduction, co-management, community education, and local participation. The paper also provides comment on the potential benefits of integrating structural and behavioral solutions in international coastal zone management efforts.     

REGION OF INFLUENCE REGRESSION FOR ESTIMATING THE 50-YEAR FLOOD AT UNGAGED SITES1

ABSTRACT: Five methods of developing regional regression models to estimate flood characteristics at ungaged sites in Arkansas are examined. The methods differ in the manner in which the State is divided into subregions. Each successive method (A to E) is computationally more complex than the previous method. Method A makes no subdivision. Methods B and C define two and four geographic subregions, respectively. Method D uses cluster/discriminant analysis to define subregions on the basis of similarities in watershed characteristics. Method E, the new region of influence method, defines a unique subregion for each ungaged site. Split-sample results indicate that, in terms of root-mean-square error, method E (38 percent error) is best. Methods C and D (42 and 41 percent error) were in a virtual tie for second, and methods B (44 percent error) and A (49 percent error) were fourth and fifth best.     

EVALUATION OF URBAN STREAM CORRIDOR RESTORATION DESIGN ALTERNATIVES USING HEC-21

ABSTRACT: The rehabilitation of urban stream channels and riparian areas involves a potentially large number of design alternatives. When substantial modifications are planned, water surface profile models (e.g., HEC-2) provide a means for a thorough and efficient evaluation of many design variations. The rehabilitation of a reach of Paradise Creek, Idaho, utilized the REC-2 model to verify the appropriateness of a new channel geometry and explore the consequences of variable floodplain geometries and excavation depths. The desirability of habitat diversity, coupled with the constraints of minimized earthwork costs and adequate flow capacity, framed the floodplain design question. The final design geometry was iteratively approached using the HEC-2 model to mimic the existing channel capacity. This modeling framework produces as output computed water surface elevations for the design channel and floodplain under any discharge. Hence, the method provides the means for demonstrating that rehabilitation designs will (or will not) cause increases in flood elevations, an assessment that is generally required for project approval.     

Cost comparison of syngas production from natural gas conversion and underground coal gasification

Underground coal gasification (UCG) is a promising technology to reduce the cost of producing syngas from coal. Coal is gasified in place, which may make it safer, cleaner and less expensive than using a surface gasifier. UCG provides an efficient approach to mitigate the tension between supplying energy and ensuring sustainable development. However, the coal gasification industry presently is facing competition from the low price of natural gas. The technology needs to be reviewed to assess its competiveness. In this paper, the production cost of syngas from an imaginary commercial-scale UCG plant was broken down and calculated. The produced syngas was assumed to be used as feedstock in liquid fuel production through the Fischer-Tropsch process or methanol synthesis. The syngas had a hydrogen (H₂) to carbon monoxide (CO) ratio of 2. On this basis, its cost was compared with the cost of syngas produced from natural gas. The results indicated that the production cost of syngas from natural gas is mainly determined by the price of natural gas, and varied from $24.46 per thousand cubic meters (TCM) to $90.09/TCM, depending on the assumed price range of natural gas. The cost of producing UCG syngas is affected by the coal seam depth and thickness. Using the Harmon lignite bed in North Dakota, USA, as an example, the cost of producing syngas through UCG was between $37.27/TCM and $39.80/TCM. Therefore, the cost of UCG syngas was within the cost range of syngas produced by natural gas conversion. A sensitivity analysis was conducted to investigate how the cost varies with coal depth and thickness. It was found that by utilizing thicker coal seams, syngas production per cavity can be increased, and the number of new wells drilled per year can be reduced, therefore improving the economics of UCG. Results of this study indicate the competitiveness of UCG regarding to natural gas conversion technologies, and can be used to guide UCG site selection and to optimize the operation strategy.     

Hydrological,Physical, and Chemical Functions and Connectivity of Non‐Floodplain Wetlands to Downstream Waters: A Review

We reviewed the scientific literature on non‐floodplain wetlands (NFWs), freshwater wetlands typically located distal to riparian and floodplain systems, to determine hydrological, physical, and chemical functioning and stream and river network connectivity. We assayed the literature for source, sink, lag, and transformation functions, as well as factors affecting connectivity. We determined NFWs are important landscape components, hydrologically, physically, and chemically affecting downstream aquatic systems. NFWs are hydrologic and chemical sources for other waters, hydrologically connecting across long distances and contributing compounds such as methylated mercury and dissolved organic matter. NFWs reduced flood peaks and maintained baseflows in stream and river networks through hydrologic lag and sink functions, and sequestered or assimilated substantial nutrient inputs through chemical sink and transformative functions. Landscape‐scale connectivity of NFWs affects water and material fluxes to downstream river networks, substantially modifying the characteristics and function of downstream waters. Many factors determine the effects of NFW hydrological, physical, and chemical functions on downstream systems, and additional research quantifying these factors and impacts is warranted. We conclude NFWs are hydrologically, chemically, and physically interconnected with stream and river networks though this connectivity varies in frequency, duration, magnitude, and timing.     

Modes of governing Canadian waste management: a case study of Metro Vancouver’s energy-from-waste controversy

Managing municipal solid waste is a pressing environmental and political concern for Canadian municipalities who bear the primary responsibility for waste management (WM). In 2015, Metro Vancouver’s (MV’s) plans to expand their capacity to expand their WM capacity with energy-from-waste technology was abandoned, despite shrinking landfill space and persistent public opposition to new landfills. Using Bulkeley et al.’s [(2005). Governing municipal waste: towards a new analytical framework. Journal of Environmental Policy and Planning, 7(1), 1–23. doi:10.1080/15239080500251700] ‘modes of governing framework’, we analyse MV’s failed attempt to expand their energy-from-waste capacity to better understand the challenges associated with governing WM in Canada. We argue that a history of downloading responsibility for WM to municipalities, regional districts, and industry has fragmented WM governance, posing a challenge for developing new waste infrastructure. We find that this localization of responsibility is incompatible with contemporary WM challenges. The scalar mismatch between waste’s material impacts and the scale at which waste is managed has resulted in co-dependence and conflict between putatively independent municipalities, regional districts, and private companies. This inhibits higher-level WM coordination while the autonomy of individual municipalities is simultaneously undermined.     

Developing alternative land-use scenarios to facilitate natural resource management across jurisdictional boundaries

Scenario planning is an effective approach for examining possible futures by exploring the implications and consequences of different policy responses to landscape stressors. We present here a case study that explores plausible futures of urban growth in Southern Nevada, USA that illustrates how scenario analysis can be used to inform region-wide resource management by spatially modeling drivers of change, resource impacts, and potential policy responses. Using a suite of energy, water and biodiversity impact models, we assess the outcomes of the various futures on priority resources, resulting in a clear basis of comparison between alternative policies and their potential outcomes. This case study demonstrates the utility of scenario modeling for natural resource management by exploring crucial policy decisions that might be made in the near-term that could have lasting and sometimes conflicting influences on regional resources over the long term.     

Do we have to incorporate ecological interactions in the sensitivity assessment of ecosystems? An examination of a theoretical assumption underlying species sensitivity distribution models

Species sensitivity distributions (SSDs) are statistical distributions which extrapolate single-species toxicity test results to ecosystem effects. This SSD approach assumes that ecological interactions between populations, such as grazing and competition, do not influence the sensitivity of ecosystems. The validity of this assumption in a simple freshwater pelagic ecosystem was tested using ecosystem modelling. For each of a 1000 hypothetical toxicants, a lognormal SSD was fitted to chronic single-species EC10s of the species present. As such, these distributions did not account for ecological interactions and were therefore termed 'conventional SSDs' (cSSDs). Next, sensitivity distributions that did take into account ecological interactions were constructed (eco-SSD) for the same 1000 toxicants, using an ecosystem model. For 254 of the 1000 hypothetical toxicants, mean and/or variance of the cSSD were significantly higher than mean and/or variance of the eco-SSD, as such rejecting the general validity of the tested assumption. A classification tree approach indicated that especially toxicants which directly affect phytoplankton (i.e. herbicides) may have a higher mean for cSSD than for eco-SSD. Conversely, means of eco-SSD and cSSD tend to be equal for toxicants directly affecting zooplankton and fish, e.g. insecticides. For the 254 hypothetical toxicants for which the tested assumption was false, a predicted no effect concentration (PNEC) calculated as the lowest single-species EC10 divided by an application factor of 10 was on average a factor 10 lower than the corresponding ecosystem-NOEC calculated by the ecosystem model.     

Climate change and coastal vulnerability assessment: scenarios for integrated assessment

Coastal vulnerability assessments still focus mainly on sea-level rise, with less attention paid to other dimensions of climate change. The influence of non-climatic environmental change or socio-economic change is even less considered, and is often completely ignored. Given that the profound coastal changes of the twentieth century are likely to continue through the twenty-first century, this is a major omission, which may overstate the importance of climate change, and may also miss significant interactions of climate change with other non-climate drivers. To better support climate and coastal management policy development, more integrated assessments of climatic change in coastal areas are required, including the significant non-climatic changes. This paper explores the development of relevant climate and non-climate drivers, with an emphasis on the non-climate drivers. While these issues are applicable within any scenario framework, our ideas are illustrated using the widely used SRES scenarios, with both impacts and adaptation being considered. Importantly, scenario development is a process, and the assumptions that are made about future conditions concerning the coast need to be explicit, transparent and open to scientific debate concerning their realism and likelihood. These issues are generic across other sectors.