Gizzard shad put a freeze on winter mortality of age-0 yellow perch but not white perch.

Four decades of observations on the limnology and fishes of Oneida Lake, New York, USA, provided an opportunity to investigate causes of mortality during winter, a period of resource scarcity for most juvenile fishes, in age-0 yellow perch (Perca flavescens) and age-0 white perch (Morone americana). This time series contains several environmental (e.g., winter severity) and biological (e.g., predator abundance) signals that can be used to disentangle multiple effects on overwinter mortality of these fishes. A multiple regression analysis indicated that age-0 yellow perch winter mortality was inversely related to fish length in autumn and to the abundance of alternative prey (gizzard shad [Dorosoma cepedianum] and white perch). However, no length-selective predation of yellow perch by one of the main predators, adult walleye (Sander vitreus), was detected. In contrast, white perch mortality was directly associated with total predator biomass and abundance of white perch in autumn, and inversely related to yellow perch abundance as a potential buffer species, but not to the abundance of gizzard shad. Winter severity was not a significant predictor of mortality for either perch species. Predicted winter starvation mortality, from a model described in the literature, was much lower than observed mortality for yellow perch. Similar models for white perch were correlated with observed mortality. These results collectively suggest that predation is the main mechanism shaping winter mortality of yellow perch, while both predation and starvation may be important for white perch. This analysis also revealed that gizzard shad buffer winter mortality of yellow perch. Although winter duration determines the northern limit of fish distributions, in mid-latitude Oneida Lake and for these species, predator-prey interactions seem to exert a greater influence on winter mortality than starvation.     

Legal Aspects of Vendor Design

This article traces and specifies various recent developments in the legal field which compel cooperation between industrial source operators and equipment vendors. Moreover, suggestions are made as to modes of avoiding costly litigation including the utilization of administrative review procedures for appealing adverse compliance determinations. Finally, an attempt is made to prepare the pollution control equipment vendor for litigation by detailing specific defenses on which the vendor can rely.     

ESP Performance with Atmospheric Fluidized-Bed Combustion

Electric utilities considering atmospheric fluidized-bed combustion (AFBC) as an economic way to reduce SO₂ and NO_x emissions at coal-fired power plants must evaluate the impact AFBC will have on existing or planned plant systems and components. Because fly ash in AFBC units can have characteristics significantly different from that generated in pulverized-coal-fired boilers, a particular concern in this regard is the performance of the plant's particulate control equipment.     

Urban ecological systems: scientific foundations and a decade of progress

Urban ecological studies, including focus on cities, suburbs, and exurbs, while having deep roots in the early to mid 20th century, have burgeoned in the last several decades. We use the state factor approach to highlight the role of important aspects of climate, substrate, organisms, relief, and time in differentiating urban from non-urban areas, and for determining heterogeneity within spatially extensive metropolitan areas. In addition to reviewing key findings relevant to each state factor, we note the emergence of tentative "urban syndromes" concerning soils, streams, wildlife and plants, and homogenization of certain ecosystem functions, such as soil organic carbon dynamics. We note the utility of the ecosystem approach, the human ecosystem framework, and watersheds as integrative tools to tie information about multiple state factors together. The organismal component of urban complexes includes the social organization of the human population, and we review key modes by which human populations within urban areas are differentiated, and how such differentiation affects environmentally relevant actions. Emerging syntheses in land change science and ecological urban design are also summarized. The multifaceted frameworks and the growing urban knowledge base do however identify some pressing research needs.     

Effects of development of wind energy and associated changes in land use on bird densities in upland areas

Wind energy development is the most recent of many pressures on upland bird communities and their habitats. Studies of birds in relation to wind energy development have focused on effects of direct mortality, but the importance of indirect effects (e.g., displacement, habitat loss) on avian community diversity and stability is increasingly being recognized. We used a control-impact study in combination with a gradient design to assess the effects of wind farms on upland bird densities and on bird species grouped by habitat association (forest and open-habitat species). We conducted 506 point count surveys at 12 wind-farm and 12 control sites in Ireland during 2 breeding seasons (2012 and 2013). Total bird densities were lower at wind farms than at control sites, and the greatest differences occurred close to turbines. Densities of forest species were significantly lower within 100 m of turbines than at greater distances, and this difference was mediated by habitat modifications associated with wind-farm development. In particular, reductions in forest cover adjacent to turbines was linked to the observed decrease in densities of forest species. Open-habitat species’ densities were lower at wind farms but were not related to distance from turbines and were negatively related to size of the wind farm. This suggests that, for these species, wind-farm effects may occur at a landscape scale. Our findings indicate that the scale and intensity of the displacement effects of wind farms on upland birds depends on bird species’ habitat associations and that the observed effects are mediated by changes in land use associated with wind-farm construction. This highlights the importance of construction effects and siting of turbines, tracks, and other infrastructure in understanding the impacts of wind farms on biodiversity.     

Cation transport by bone marrow cells from vitamin-E-deficient mice

This work was supported financially by the ministry of the Interior at Bonn. The authors wish to acknowledge the valuable and skillful technical assistance of W. Steffens and E. Bardon.     

Who's on the greenway: Socioeconomic,demographic, and locational characteristics of greenway users

In response to continued public concern sparked by the loss of open space and greenbelts around American cities, greenways have gained nationwide popularity as a land conservation strategy. This study examines the socioeconomic, demographic, and locational characteristics of greenway users. Three hundred twenty users on four trails of the Capital Area Greenway System in Raleigh, North Carolina, were surveyed. The Raleigh system is extensive, providing 43.7 km (27 mi) of trails, thus allowing examination of greenway use in a variety of settings. The survey findings indicated that most patrons were drawn from within an 8.05-km (5-mi) radius of the greenway. The typical Capital Area Greenway user is a white female between the age of 16 and 34 with no children. Socioeconomically, greenway users are employed, well-educated, and have above average incomes. A disproportionate share of greenway visitors belong to an environmental group.     

Hypoxic life of intertidal acorn barnacles

Oxygen levels were monitored within the mantle cavities of three barnacle species ( Chthamalus stellatus, Semibalanus balanoides, Elminius modestus), using optode microsensors. Conditions were always hypoxic, even when barnacles were actively using the prosoma and cirri to pump aerated seawater into the mantle cavity. Mantle fluid oxygen concentrations were extremely variable; behaviour and oxygen concentrations were not closely coupled. Ventilation of the mantle cavity depended partially on external water flow, with higher and more stable mantle fluid oxygen concentrations being sustained when the water around barnacles was agitated. During emersion, barnacles initially pumped seawater between the mantle cavity and the cone above the opercular plates to achieve ventilation. As water was lost it was replaced by air bubbles, eventually resulting in an air-filled mantle cavity. In S. balanoides and E. modestus, once the mantle cavity was filled with air, the barnacle usually used up the oxygen within the bubble within 2–3 h and did not regain oxic conditions until the barnacle was reimmersed in seawater. In C. stellatus, the air bubble was repeatedly refreshed for many hours by pneumostome formation. In response to low environmental salinity, all three species closed the opercular plates firmly and rapidly used up oxygen within the mantle fluid.