Exploratory Analysis of the Winter Chemistry of Five Lakes on the North Slope of Alaska1

Abstract: Lakes are important water resources on the North Slope of Alaska. Freshwater is required for oilfield production as well as exploration, which occurs largely on ice roads and pads. Since most North Slope lakes are shallow, the quantity and quality of the water under ice at the end of winter are important environmental management issues. Currently, water‐use permits are a function of the presence of overwintering fish populations, and their sensitivity to low oxygen concentrations. Sampling of five North Slope lakes during the winter of 2004‐2005 shed some light on the winter chemistry of four lakes that were used as water supplies and one undisturbed lake. Field analysis was conducted for oxygen, conductivity, pH, and temperature throughout the lake depth, as well as ice thickness and water depth. Water samples were retrieved from the lakes and analyzed for Na, Ca, K, Mg, Fe, dissolved‐organic carbon, and alkalinity in the laboratory. Lake properties, rather than pumping, were the best predictors of oxygen depletion, with the highest dissolved‐oxygen levels maintained in the lake with the lowest concentration of constituents. Volume weighted mean dissolved‐oxygen concentrations ranged from 4 to 94% of saturation in March. Dissolved oxygen and specific conductance data suggested that the lakes began to refresh in May.     

Solid waste characterization and recycling potential for a university campus

Integrated waste management systems are one of the greatest challenges for sustainable development. For these systems to be successful, the first step is to carry out waste characterization studies. In this paper are reported the results of a waste characterization study performed in the Campus Mexicali I of the Autonomous University of Baja California (UABC). The aim of this study was to set the basis for implementation of a recovery, reduction and recycling waste management program at the campus. It was found that the campus Mexicali I produces 1ton of solid wastes per day; more than 65% of these wastes are recyclable or potentially recyclable. These results showed that a program for segregation and recycling is feasible on a University Campus. The study also showed that the local market for recyclable waste, under present conditions - number of recycling companies and amounts of recyclables accepted - can absorb all of these wastes. Some alternatives for the potentially recyclables wastes are discussed. Finally some strategies that could be used to reduce waste at the source are discussed as well.     

Is the integration of hormesis and essentiality into ecotoxicology now opening Pandora's Box?

Hormesis and essentiality are likely real and common effects at the level of the individual. However, the widespread incorporation of stimulatory effects into applications of ecotoxicology requires the acceptance of assumptions, value judgements and possibly lowering of water/sediment quality standards. There is also currently little data appropriate for considering hormetic effects in the ecotoxicological context. Except perhaps in the case of fitting concentration-response curves, it is not clear that incorporation of hormetic and essentiality type responses into ecotoxicology is necessary. Furthermore, its incorporation presents considerable intellectual and practical changes for ecotoxicology and could have unanticipated consequences.     

Utility of North Atlantic Right Whale Museum Specimens for Assessing Changes in Genetic Diversity

Abstract: We examined six historical specimens of the endangered North Atlantic right whale ( Eubalaena glacialis ) using DNA isolated from documented baleen plates from the late nineteenth and early twentieth centuries. Sequences from the mitochondrial DNA (mtDNA) control region from these samples were compared with those from a near-exhaustive survey (269 of approximately 320 individuals) of the remaining right whales in the western North Atlantic Ocean. Our results suggest that there has been only relatively modest change in maternal lineage diversity over the past century in the North Atlantic right whale population. Any significant reduction in genetic variation in the species most likely occurred prior to the late nineteenth century. One historical specimen was from the last documented female capable of propagating one of the maternal lineages in the population today; no females in the existing population have been found to carry this mtDNA haplotype. Analysis of the only specimens from the eastern North Atlantic right whale population ever to be examined revealed that eastern and western North Atlantic right whales may not have been genetically differentiated populations. Loss of gene diversity experienced by North Atlantic right whales over the last century has been modest, and the six decades of protection have been successful in maintaining much of the maternal lineage diversity that was present in the late nineteenth century.     

Specialisations of swimming muscles in the pelagic antarctic fish Pleuragramma antarcticum

The distribution and ultrastructure of muscle-fibre types has been investigated in adult and juvenile specimens of the pelagic high-antarctic silverfish Pleuragramma antarcticum Boulenger, 1902 collected from the South Shetland Islands during the winter of 1984/1985. Two main fibre-types were identified in araldite-embedded material. The axial musculature was mainly composed of poorly vascularised, largediameter muscle fibres which were densely packed with myofibrils (volume density 81 and 72% for adults and juveniles, respectively). These ultrastructural characteristics are typical of fast-twitch fibres. The number of capillaries ner unit cross-sectional area and the volume density of mito     

The encrusting spongeHalisarca laxus: population genetics and association with the ascidianPyura spinifera

The encrusting spongeHalisarca laxus forms a seemingly obligate association with the stalked solitary ascidianPyura spinifera. In 1991 we examined spatial variation and short-term temporal variation in this association at three neighbouring sites in southeastern Australia. This sponge dominated the surface of almost all the 500 individual ascidians examined, with mean cover usually exceeding 90%. This pattern was consistent among sites and throughout the year of the study. The domination of a small isolated patch of habitable substratum by a sponge is most unusual, given that they are regarded as relatively poor recruiters. To understand how this association might be maintained, we determined the underlying genotypic diversity of the sponge population using starch-gel electrophoresis.P. spinifera is a clump-forming ascidian and usually occurs in clumps of up to 22 individuals. Electrophoretic surveys, based on six variable allozyme loci, revealed that at a total of five plots within three neighbouring New South Wales populations, single sponge genotypes may cover entire ascidian clumps; although a clump sometimes played host to more than one sponge clone. Allele frequencies (averaged across four loci that appear to conform to Mendelian inheritance) showed little variation among populations (standardised genetic variance,F _ST=0.013). Nevertheless, sponge populations were genotypically diverse, with samples from 63 of 172 individual clumps displaying unique clonal genotypes. Moreover, multi-locus genotypic diversity within all sites approached the level expected for sexual reproduction with random mating. Taken together, these data imply thatH. laxus produces sexually-derived larvae that are at least moderately widelly dispersed. Given the relatively small size of the patches that this sponge inhabits, we also conclude that these larvae are good colonists and good spatial competitors on their ascidian hosts.     

萨尔瓦多红树林管理问题中的补贴办法

本文概述了引起萨尔瓦多红树林退化的各种因素,并分析了拟议中的红树林产权变化对贫困的海岸带社区红树林的意义.目前萨尔瓦多红树林生态系统的采伐和转化模式可通过补贴权利的透镜来观察,这种补助就是为特定用途向一些参与者授予财产权(而不授权给别人).遗憾的是,对红树林资源的使用进行管理的现有法律法规体系是相互矛盾和含混不清的.一些现行的法律对生态系统的使用和转变问题做出了完全相反的规定.如果不对各项补贴权利重新定义,就不能确保对红树林进行合理、持续的管理.但这种权利的重新定义应考虑其生活与生态系统的健康状况密切相关的那些群体的需要.     

Cross-hybridization of the chromosome 13/21 alpha satellite DNA probe to chromosome 22 in the prenatal screening of common chromosomal aneuploidies by fish

In a routine application of commercially available centromeric DNA probes for the prenatal screening of common trisomies involving the autosomes 13, 18, and 21, and sex chromosomes, four cases of discrepancy between fluorescence in situ hybridization (FISH) results and follow-up cytogenetic analysis were observed from a total of 516 cases of amniocentesis. In three of these cases, the results were false negative, and in one false positive. In this case, amniocentesis was performed because of a positive triple test in a 34-year-old woman with previous infertility treatment. The alpha satellite DNA probe for chromosomes 13/21 revealed five signals in 50 per cent of uncultured amniocytes, while standard cytogenetic analysis showed a normal karyotype. FISH analysis on metaphase chromosomes demonstrated the location of the additional signal in the centromeric region of chromosome 22. This additional signal was also present in the centromeric region of chromosome 22 of the mother, providing evidence for a possible inherited polymorphism in chromosome 22 responsible for unspecific hybridization with the alpha satellite probe for chromosomes 13/21 in this case. The observed polymorphism in centromeric regions may contribute to unreliability of the use of the 13/21 alpha satellite probe for prenatal screening by FISH.