Trill performance components vary with age, season, and motivation in the banded wren

Acoustic displays with difficult-to-execute sounds are often subject to strong sexual selection because performance levels are related to the sender’s condition or genetic quality. Performance may also vary with age, breeding stage, and motivation related to social context. We focused on within-male variation in four components of trill performance in banded wren (Thryophilus pleurostictus) songs: note consistency, frequency bandwidth, note rate, and vocal deviation. The latter is a composite measure reflecting deviation from the performance limit on simultaneously maximizing both frequency bandwidth and note rate. We compared the changes in these song parameters at three time scales: over the course of years, across the breeding season, and at different times of the day with contrasting agonistic contexts. Vocal deviation decreased and note consistency increased between years, suggesting that experience may improve individual proficiency at singing trills. Consistency also increased across the season, confirming that practice is important for this parameter. Although there was no significant seasonal change in vocal deviation, one of its components, note rate, increased during the season. Neither vocal deviation nor consistency varied with agonistic context. However, note rate increased during playback experiments simulating territorial intrusions compared to dawn chorus singing. The magnitude of a male’s increase in note rate was positively correlated with his aggressive behavior during the playback experiment. Thus consistency, bandwidth, and vocal deviation indicate age, whereas trill rate flexibly indicates the singer’s aggressive motivation. We also found evidence of a within-male trade-off between vocal deviation and consistency.     

A high-resolution historical sediment record of nutrients,trace elements and organochlorines (DDT and PCB) deposition in a drinking water reservoir (Lake Brêt,Switzerland) points at local and regional pollutant sources

The ¹³⁷Cs and ²¹⁰Pb dating of a 61-cm long sediment core retrieved from a drinking water reservoir (Lake Brêt) located in Switzerland revealed a linear and relatively high sedimentation rate (～1 cm year^?1) over the last decades. The continuous centimeter scale measurement of physical (porewater and granulometry), organic (C_org, P, N, HI and OI indexes) and mineral (C_min and lithogenic trace elements) parameters therefore enables reconstructing the environmental history of the lake and anthropogenic pollutant input (trace metals, DDT and PCBs) at high resolution. A major change in the physical properties of the lowermost sediments occurred following the artificial rise of the dam in 1922. After ca. 1940, there was a long-term up-core increase in organic matter deposition attributed to enhance primary production and anoxic bottom water conditions due to excessive nutrient input from a watershed predominantly used for agriculture that also received domestic effluents of two wastewater-treatment plants. This pattern contrasts with the terrigenous element input (Eu, Sc, Mg, Ti, Al, and Fe) which doubled after the rising of the dam but continuously decreased during the last 60 years. By comparison, the trace metals (Cu, Pb and Hg) presented a slight enrichment factor (EF) only during the second part of the 20th century. Although maximum EF Pb (>2) occurred synchronously with the use of leaded gasoline in Switzerland (between ca. 1947 and 1985) the Hg and Cu profiles exhibited a relatively similar trend than Pb during the 20th century, therefore excluding the alkyl-lead added to petrol as the dominant (atmospheric) source of lead input to Lake Brêt. Conversely, the Cu profile that did not follow the decrease registered in Pb and Hg during the last 10 years, suggests an additional source of Cu probably linked to the impact of agricultural activities in the area. In absence of heavy industries in the catchment, the atmospheric deposition of DDT and PCBs via surface runoff followed the historical emissions of POPs in Switzerland. Such result highlights the regional contamination of freshwater resources by the large-scale emission of toxic industrial chemicals in the 1960s and 1970s as well as the efficiency of the regulatory measures subsequently taken.     

Significance of salinity and silicon levels for growth of a formerly estuarine eelgrass (Zostera marina) population (Lake Grevelingen, The Netherlands)

Since the early 1980s, the eelgrass, Zostera marina L., population in the saline Lake Gevelingen, The Netherlands, is rapidly declining. An earlier study, in which long-term data on eelgrass coverage in this former estuary were correlated with several environmental variables, showed only one significant correlation: coverage was positively related to water column silicon levels. In addition, a negative correlation with salinity was observed, but this was not significant. In the present study, the effect of silicon and the effect of salinity on the development of Z. marina were investigated experimentally. Enhancement of dissolved silicon concentrations in the water did not stimulate Z. marina above-ground production or an increase in final above- and below-ground biomass. The highly significant correlation between eelgrass coverage and water column silicon levels, thus, remains to be explained. The results of the growth experiments did, however, demonstrate a clear effect of salinity on Z. marina growth. Plants cultured at 22 psu showed a higher production of shoots and leaves, resulting in more above-ground biomass, than plants grown at 32 psu. In addition, below-ground biomass was also higher at 22 psu. Measurements of chlorophyll a fluorescence, performed with a PAM-fluorometer, indicated a reduction of photosynthesis in the high-salinity treatments. Thus, low salinity stimulates development of Z. marina from Lake Grevelingen. Eelgrass from such a historically estuarine area may be more sensitive to high salinities than other, more marine populations. Recovery of the autochthonous eelgrass population is expected to be favoured when the estuarine conditions of the seagrass area are re-established, or when restoration programmes are carried out with allochthonous ecotypes that are less sensitive to high salinities. Received: 23 June 1998 / Accepted: 19 November 1998     

森林碳获取的生态和经济潜力:南美案例

复林项目的成本决定了它们与其它减轻大气中日益增加的CO2浓度的方法的竞争力.我们量化了南美两国--厄瓜多尔和阿根廷--人工林和次生林地上生物量和土壤中的碳获取量,并计算了短期碳获取成本.每短期认证减排单位成本为0.1～2.7美元/Mg CO2,主要取决于机会成本、立地适宜性、贴现率和认证成本.在厄瓜多尔,次生林是一种可行并合算的方法;在阿根延,在适宜性高的土地上进行复林相对便宜一些.我们的研究结果可用于设计有成本效益的CO2汇项目和为土地所有者协商公平的碳价格.     

A framework for integrated resource planning in the electric power sector

A framework is presented showing the process of integrated resource planning in the electric power sector. This takes into account the traditional utility planning process, and shows how the use of advanced decision analysis tools would facilitate the integration of demand-side management (DSM) and environmental factors. The concept of influence diagram is introduced in the utility planning arena. Using the interdependent data analysis (IDA) technique, a way is shown to provide the probability estimates necessary for the influence diagram. The IDA technique allows the use of expert opinions and intuitive judgements to develop the necessary probability estimates. A sample case study is presented where the issue of environmental impact from stack emissions is incorporated. A base case coal option is compared against a gas turbine combined cycle (GTCC) alternative. Energy costs from these two options are compared by taking into account the capital, licensing, fuel, operation and maintenance, and emissions related costs.     

Aerosol composition as a function of haze and humidity levels in the Southwestern U.S.

The observed composition of visibility-reducing aerosols in the Grand Canyon region is summarized in climatological terms. Observations are from SCENES, a measurement program extending from 1984 to 1989. Results are presented as average mass balances stratified by various factors.Aerosols were found to exhibit substantial seasonal variation, but little systematic diurnal variation. Crustal material was a dynamic component, and peaked during springtime. Aerosol composition, but not total concentration, depended strongly on ambient relative humidity, with crustal material augmented at low humidities and sulfates augmented at high humidities. Total fine-particle concentrations correlated strongly with light scattering, as expected; however, little association between chemical composition and light scattering was observed.     

Trisomy 2 due to a 3:1 segregation in an abortion studied by QF-PCR and CGH

Balanced reciprocal translocation is one of the known causes of recurrent spontaneous abortions. Cytogenetic studies of unbalanced miscarriages are difficult due to the growth failure of early loss and usually macerated abortions. We present a molecular study of an abortion in which the father carries a balanced reciprocal translocation t(2;17)(q32.1;q24.3) using QF-PCR and CGH techniques. DNA analysis showed the presence of a trisomy 2 due to a 3:1 interchange segregation. Recombinant events could also be investigated by comparing DNA samples from the family. We propose QF-PCR in addition to CGH as an efficient diagnostic method to improve our knowledge of unbalanced offspring in balanced translocation carriers. Copyright © 2005 John Wiley & Sons, Ltd.