Effects of El Niño on distribution and reproductive performance of Black Brant

Climate in low-latitude wintering areas may influence temperate and high-latitude breeding populations of birds, but demonstrations of such relationships have been rare because of difficulties in linking wintering with breeding populations. We used long-term aerial surveys in Mexican wintering areas and breeding areas in Alaska, USA, to assess numbers of Black Brant (Branta bernicla nigricans; hereafter brant) on their principal wintering and breeding area in El Ni?o and non-El Ni?o years. We used Pollock's robust design to directly estimate probability of breeding and apparent annual survival of individually marked brant at the Tutakoke River (TR) colony, Alaska, in each year between 1988 and 2001. Fewer brant wintered in Mexico during every El Ni?o event since 1965. Fewer brant were observed on the principal breeding area following each El Ni?o since surveys began in 1985. Probability of breeding was negatively related to January sea surface temperature along the subtropical coast of North America during the preceding winter. Between 23% (five-year-olds or older) and 30% (three-year-olds) fewer brant nested in 1998 following the strong El Ni?o event in the winter of 1997-1998 than in non-El Ni?o years. This finding is consistent with life history theory, which predicts that longer-lived species preserve adult survival at the expense of reproduction. Oceanographic conditions off Baja California, apparently by their effect on Zostera marina (eelgrass), strongly influence winter distribution of brant geese and their reproduction (but not survival), which in turn affects ecosystem dynamics in Alaska.     

Understanding Fish Behavior,Distribution, and Survival in Thermal Effluents Using Fixed Telemetry Arrays: A Case Study of Smallmouth Bass in a Discharge Canal During Winter

Advances in telemetry have facilitated the continuous monitoring of fish position and movement. At present, there are few examples where this approach has been applied to environmental monitoring or assessment. Here we 1) present a case study that used a fixed antenna array and continuously scanning coded receiving system to monitor the movement of radio-tagged smallmouth bass (Micropterus dolomieu) in a thermal discharge canal on Lake Erie during the winter of 1998/1999, and 2) evaluate the use of fixed telemetry arrays for environmental monitoring. Although the number of radiotagged bass in the canal decreased gradually over time, fish spent the majority of the winter in the canal. When in the canal, bass selected areas upstream of the tempering pumps where water was the warmest. This region was also high in habitat complexity, had adequate velocity refuges, and abundant forage. Despite residing in the thermal effluent throughout the winter, none of the fish monitored were observed to participate in reproductive activities in the canal in the Spring. Interestingly, during a biofouling chlorination pulse in May, 50% of radiotagged fish still residing in the canal left and did not return during the monitoring period. Utility infrastructure accessible to fish, including thermal effluents, should be considered as fish habitat and managed accordingly to minimize mortality and sublethal effects on resident and transient fish. Fixed telemetry arrays that permit the continuous monitoring of fish behavior as described in this paper are widely applicable to many issues in environmental management, monitoring, and conservation.     

Water quality changes in a polluted stream over a twenty-five-year period

The Deckers Creek watershed in northern West Virginia (USA), containing a land area of 166 km2 (63 mi2), has a long history of industrial development and attendant environmental abuses from both land and water pollution practices. The water in Deckers Creek was sampled in 1974 at 29 locations along the main stem and resampled in 1999-2000 to determine water quality changes over this 25-year period. Water samples were analyzed for pH, acidity, alkalinity, iron, and calcium at both times, while aluminum, manganese, zinc, and fecal coliform (FC) bacteria densities were added in 1999-2000. Water at almost all sampling points showed lower acidity and metal contents in 1999-2000 compared with 1974. Water pH increased at the mouth from 5.4 in 1974 to 6.0 in 1999-2000. Acidity and iron concentrations were decreased an average of 70% in the upper stretches of the creek. However, one major untreated point source of water from an abandoned underground mining complex continues to degrade the quality of the creek in its lower stretches. In the upper section, the water quality in Deckers Creek has improved due to decreased surface and underground coal mining activities, reclamation of abandoned and recently permitted surface mined lands, and natural healing of past land use scars from timbering and mining over time. The decrease in mineral extraction activities and the reclamation of disturbed lands has occurred due to the passage and enforcement of water quality and land reclamation laws and regulations. More time and additional reclamation projects will continue to enhance the water quality in the creek. Improved water chemistry in the majority of the creek, however, shows the previously unnoticeable biological contamination from sewage inputs.     

Book reviews

Our Stolen Future. How man-made chemicals are threatening our fertility, intelligence and survival. T. Colborn, J. P. Myers & D. Dumanoski, 1996, Boston, Little, Brown, 306 pp. ISBN 0 316 87546, £18.99

Environmental Sociology: a social constructionist perspective. John Hannigan, 1995, London, Routledge, ISBN 0 415 112 559, £12.99

Citizen Science: a study of people, expertise and sustainable development. Alan Irwin, 1995, London, Routledge, ISBN 0 415 130 107, £13.99

The True Costs of Road Transport. David Maddison, David Pearce, Olof Johansson, Edward Calthrop, Todd Litman & Eric Verhoef, 1996, London, Earthscan, 242 pp. ISBN 185 383 2685, £10.95

Car Dependence: a report for the RAC Foundation for Motoring and the Environment. RAC Foundation for Motoring and the Environment, 1995, London, 154 pp. ISBN 086211355 5

Local Sustainability: turning sustainable development into practical action in our communities. Roger Few (Ed.), Leicester Environment City Trust, 1996, Leicester, Environ Trust, 100 pp., £28.00, [Available from: Environ Parkfield, Western Park, Leicester, LE3 6HX, UK]

Successful Environment Management in a Week. Mark Yoxon, 1996, London, Hodder & Stoughton, 96 pp. ISBN 0 340 66374 X, £6.99

Principles of Environmental and Resource Economics. H. Folmer, H. Landis Gabel & H. Opschoor (Eds), 1995, Aldershot, Edward Elgar, 512 pp. ISBN 1 85898 224 3, £85.00

The Contingent Valuation of Environmental Resources: methodological issues and research needs. David Bjornstad & James R. Khan (Eds), 1996, Cheltenham, UK and Brookfield USA, Edward Elgar, ISBN 1 858983215

Towards Sustainability. Peter Martin & Colin Hutchinson, 1996, London, Office for Public Management, £5.45

Conservation and the Consumer: understanding environmental concern. Paul Hackett, 1995, London, Routledge, 229 pp. ISBN 0 415 08096 7, £45.00     

Monitoring and management of streambank erosion and natural revegetation on the lower Gordon River,Tasmanian Wilderness World Heritage Area,Australia

The wash from high-speed tourist cruise launches causes erosion of the formerly stable banks of the lower Gordon River within the Tasmanian Wilderness World Heritage Area. Speed and access restrictions on the operation of commercial cruise vessels have considerably slowed, but not halted erosion, which continues on the now destabilized banks. To assess the effectiveness of restrictions, bank erosion and natural revegetation are monitored at 48 sites using erosion pins, survey transects, and vegetation quadrats. The subjectively chosen sites are grouped on the basis of geomorphology and bank materials. The mean measured rate of erosion of estuarine banks slowed from 210 to 19 mm/year with the introduction of a 9 knot speed limit. In areas where cruise vessels continue to operate, alluvial banks were eroded at a mean rate of 11 mm/yr during the three-year period of the current management regime. Very similar alluvial banks no longer subject to commercial cruise boat traffic eroded at the slower mean rate of 3 mm/yr. Sandy levee banks have retreated an estimated maximum 10 m during the last 10–15 years. The mean rate of bank retreat slowed from 112 to 13 mm/yr with the exclusion of cruise vessels from the leveed section of the river. Revegetation of the eroded banks is proceeding slowly; however, since the major bank colonizers are very slow growing tree species, it is likely to be decades until revegetation can contribute substantially to bank stability.     

Hedgerows and hedgerow networks in landscape ecology

Hedgerows originated and coexist with agriculture. Their internal structure and species diversity vary widely with origin (planted, spontaneous, or remnant), farming practices in adjacent fields, and the refined art of hedgerow management. Most hedgerow species are forest-edge species, and apparently none is limited to hedgerows. Wide hedgerows composed of trees and shrubs appear to function as corridors for movement of many plants and animals across a landscape. The reduction of crop loss, by dampening pest population fluctuations with hedgerow predators, remains a hypothesis for study.Field microclimate downwind of a hedgerow is modified about 16 times the hedgerow height (h) for evaporation, and approximately 28 h for wind speed. A turbulent wind pattern with harsher microclimate is present at 6–8 h if a second hedgerow is nearby downwind. Zones of higher crop productivity at 3- to 6-h downwind, and 2- to 6-h upwind of a second hedgerow may be expected. Overall, we expect little short-term difference in farm-field production with or without hedgerows.Evidence suggests that hedgerow networks, and especially their mesh size (of fields), exert a major control on many major landscape fluxes. Such fluxes include animal populations, wind speed, evapotranspiration and soil desiccation, soil erosion and nutrient runoff, species movement along network lines, and movement of field species across the network. In a relatively short period, the hedgerow ecosystem, with no unique species, has attained a metastable equilibrium, which is regulated by enormous human inputs.More than 20 economic roles of hedgerows are pinpointed. The roles, providing resources and protection of resources, are poorly known quantitatively. We conclude that hedgerows perform diverse functions for society and the farmer that are both economically and ecologically significant.     

Metal capital sustaining a North American city: Iron and copper in New Haven, CT

A detailed inventory shows that an average resident of the City of New Haven depends on a per capita capital stock of 9200 kg/c of iron and 144 kg/c of copper in the city infrastructure, buildings, transportation systems, and equipment. Of the iron stock 28% is in items such as rail cars and ships in ocean trade not permanently within the city, and 22% is devoted to receiving and delivering oil fuel to the city and its surrounding communities. Copper is principally used in the distribution of electric power and in water piping within buildings. The city's 9200 kg/c of iron stock-in-use is less than the 13,000 kg/c national average due to New Haven's lack of heavy industry and relatively small number of large buildings. The 144 kg/c of copper stock-in-use is only 58% of the overall value for the United States, but is comparable to that in cities such as Stockholm, Sweden. Attainment of a level of iron and copper services with contemporary technology in less developed countries to the level enjoyed in New Haven would require consumption of the presently identified world copper resources.     

Estimating Evapotranspiration and Seepage for a Sinkhole Wetland From Diurnal Surface‐Water Cycles1

Abstract: This study used measured diurnal surface‐water cycles to estimate daily evapotranspiration (ET) and seepage for a seasonally flooded sinkhole wetland. Diurnal surface‐water cycles were classified into five categories based on the relationship between the surface‐water body and the surrounding ground‐water system (i.e., recharge/discharge). Only one class of diurnal cycles was found to be suitable for application of this method. This subset of diurnal cycles was used to estimate ET and seepage and the relative importance of each transfer process to the overall water budget. The method has limited utility for wetlands with erratic hydrologic regimes (e.g., wetlands in urban environments). This is due to violation of the critical assumption that the inflow/outflow rate remains constant throughout the day. For application to surface‐water systems, the method is typically applied with an assumed specific yield of 1.0. This assumption was found to be invalid for application to surface‐water systems with a noncylindrical pond geometry. An overestimation of ET by as much as 60% was found to occur under conditions of low pond stage and high water loss. The results demonstrate the high ET rates that can occur in isolated wetlands due to contrasting roughness and moisture conditions (oasis and clothesline effects). Estimated ET rates ranged from 4.1 to 18.7 mm/day during the growing season. Despite these large ET rates, seepage (recharge) was found to be the dominant water loss mechanism for the wetland.     

The Park Made of Oil: Towards a Historical Political Ecology of the Kenneth Hahn State Recreation Area

Within the park-deprived inner-city landscapes of Los Angeles, an unprecedented change is underway. Long considered to be the epitome of anti-nature, Los Angeles is witnessing a boom in park development and ecological restoration. Derelict, blighted and contaminated inner-city brownfield sites are being converted to greenspaces, nature parks and wildlife refuges. Indeed, Los Angeles has been the recent recipient of hitherto unimaginable political and fiscal support to ameliorate the dearth of parks in its neglected urban core. This paper situates the current round of park development within its historical context, by focusing on a very particular local site—the Kenneth Hahn State Recreation Area. Applying the theoretical lens of political ecology, the authors trace some of the political, economic, ecological and institutional factors from the late 1920s onwards, which engendered the creation of a park atop an oilfield. In so doing, the authors deepen the understanding of how local greenspace allocation, poverty, race and political power are oftentimes complexly entangled. Precursor to a much larger project currently in the planning and development stages, the creation of the Kenneth Hahn State Recreation Area reveals some of the ways that the Southern California oil industry has shaped nature spaces in Los Angeles.