Seasonal speedup along the western flank of the Greenland Ice Sheet

It has been widely hypothesized that a warmer climate in Greenland would increase the volume of lubricating surface meltwater reaching the ice-bedrock interface, accelerating ice flow and increasing mass loss. We have assembled a data set that provides a synoptic-scale view, spanning ice-sheet to outlet-glacier flow, with which to evaluate this hypothesis. On the ice sheet, these data reveal summer speedups (50 to 100%) consistent with, but somewhat larger than, earlier observations. The relative speedup of outlet glaciers, however, is far smaller (<15%). Furthermore, the dominant seasonal influence on Jakobshavn Isbrae's flow is the calving front's annual advance and retreat. With other effects producing outlet-glacier speedups an order of magnitude larger, seasonal melt's influence on ice flow is likely confined to those regions dominated by ice-sheet flow.     

Changes in soil chemistry associated with the establishment of forest gardens on eroded,acidified grassland soils in Sri Lanka

Topsoil properties were determined in forest gardens established about 20 years ago on eroded grassland soils (abandoned tea lands) in the wet zone of the Sri Lankan highlands. They were compared with adjacent, eroded grasslands (abandoned tea lands) on strongly weathered soils vs soils at earlier stages of pedogenic development in a two-way analysis of variance. Soil pH in forest gardens was, on average, 6.1, nearly one unit higher than in the adjacent grasslands. In the garden soils, the cation exchange capacity (CEC measured at pH 4.8) was nearly double, exchangeable calcium concentrations five times and exchangeable magnesium three times as high as in the grasslands soils. Total soil N content was found to be nearly 40% higher in the gardens. Topsoil gravel contents in the gardens were less than half as high as in the grasslands. The increases in exchangeable bases and N in gardens, relative to grasslands, were attributed to increased nutrient retention and acquisition. Higher retention was partly due to the higher CEC_pH4.8, and probably to reduced erosion and increased, continuous fine root density in the garden topsoils. Higher field CEC in gardens was likely to result from generally higher C contents and from the reversal of acidification, presumably caused by base accumulation and decomposition processes. Our results suggest that forest garden establishment on degraded grasslands can lead to accumulation of mobile nutrients in the topsoil, probably due to increased nutrient retention, subsoil uptake and litter input exceeding nutrient uptake by the standing biomass.     

A bulk tank milk survey of Ostertagia ostertagi antibodies in dairy herds in Prince Edward Island and their relationship with herd management factors and milk yield

The objective of this study was to quantify the relationship of the levels of antibodies to Ostertagia ostertagi in bulk-tank milk samples from Prince Edward Island (PEI) dairy farms to milk production and to herd-management practices potentially related to gastrointestinal nematode infections. The milk samples were obtained from 289 to 322 dairy farms during 2000; production and management data were available from 197 and 200 farms, respectively. Cow exposure to pasture and whole-herd anthelmintic treatment were the only herd management variables significantly associated with antibody levels in the fall of 2000. An increase in antibody levels from the observed 25th percentile to the 75th percentile (interquartile range) was associated with a drop in milk production of 1.2 kg/cow/day. The results of this study indicate that the enzyme-linked immunosorbent assay for O. ostertagi antibody is a potentially useful technique to measure parasite exposure in adult dairy cows and that parasite burdens in lactating cattle in PEI have an important impact on milk production.     

Effects of changing temperature on benthic marine life in Britain and Ireland

• 1. The coastal waters surrounding Britain and Ireland became warmer during the 20th century and, according to the UK Climate Impact Programme 2002 scenarios of change and other sources, average annual seawater temperatures may rise a further 2°C or more by the 2050s. This warming is part of a global rise in sea‐ and air‐surface temperatures that will cause changes in the distribution and abundance of species.
• 2. Initially, there will not be a wholesale movement northwards of southern species or retreat northwards of northern species, because many additional factors will influence the responses of the different organisms. Such factors include the hydrodynamic characteristics of water masses, the presence of hydrographical and geographical barriers to spread and the life history characteristics (reproductive mode, dispersal capability and longevity) of species. Survey data over the past century show how organisms react to changes of the order of 0.5°C, and in the last two decades, when sea temperatures have risen by as much as 1°C, there have been significant local changes in the distribution of intertidal organisms. These past changes provide a clue to more extensive changes expected in the future if global warming develops as predicted.
• 3. Where species affected by climate change are dominant or key structural or functional species in biotopes, there may be a change in the extent and distribution of those biotopes. Some, dominated by predominantly northern species such as the horse mussel Modiolus modiolus, may decline and reduce their value as rich habitats for marine life. Others, characterized by southern species, for example the sea fan Eunicella verrucosa and the alcyonacean Alcyonium glomeratum, may increase in extent.
• 4. Using information on the life history characteristics of species, their present distribution and other factors, a key supported by a decision tree has been constructed to identify ‘types’ of organism according to their likely response to temperature rise. Conspicuous and easily identified rocky substratum species are good candidates to track change. Using the key, many species are shown as likely to increase their range northwards significantly. In contrast, fewer will decline in abundance and extent in the north. If, as anticipated, global warming continues, then species with distributions already accurately mapped, or being mapped at present, will provide baseline data to test forecasts.

Copyright © 2004 John Wiley & Sons, Ltd.     

Incidence and effects of West Nile virus infection in vaccinated and unvaccinated horses in California

A prospective cohort study was used to estimate the incidence of West Nile virus (WNV) infection in a group of unvaccinated horses (n = 37) in California and compare the effects of natural WNV infection in these unvaccinated horses to a group of co-mingled vaccinated horses (n = 155). Horses initially were vaccinated with either inactivated whole virus (n = 87) or canarypox recombinant (n = 68) WNV vaccines during 2003 or 2004, prior to emergence of WNV in the region. Unvaccinated horses were serologically tested for antibodies to WNV by microsphere immunoassay incorporating recombinant WNV E protein (rE MIA) in December 2003, December 2004, and every two months thereafter until November 2005. Clinical neurologic disease attributable to WNV infection (West Nile disease (WND)) developed in 2 (5.4%) of 37 unvaccinated horses and in 0 of 155 vaccinated horses. One affected horse died. Twenty one (67.7%) of 31 unvaccinated horses that were seronegative to WNV in December, 2004 seroconverted to WNV before the end of the study in November, 2005. Findings from the study indicate that currently-available commercial vaccines are effective in preventing WND and their use is financially justified because clinical disease only occurred in unvaccinated horses and the mean cost of each clinical case of WND was approximately 45 times the cost of a 2-dose WNV vaccination program.     

Sperm production and quality in European eel (Anguilla anguilla) in relation to hormonal treatment

Aquaculture production relies on controlled management of gametogenesis, especially in species where assisted reproduction is needed for obtaining gametes in captivity. The present study used human chorionic gonadotropin (hCG) treatments to induce and sustain spermatogenesis in European eel (Anguilla anguilla). The aim was to evaluate effects of strip-spawning timing (12 vs. 24 hr) after weekly administration of hCG and the necessity of a primer dose (in addition to weekly hormonal treatment) prior to strip spawning (primer vs. no-primer) on sperm quality parameters. Sperm parameters included milt production (weight), density and sperm kinematics at Week 9, 11 and 13 after onset of treatment. Spermiation commenced in 11.5% of males in Week 5 and by Week 9, and all males produced milt. Male weight, milt production, sperm density and spermatocrit did not differ among hormonal treatments during the experimental period. Overall, male weight decreased from 106.3 to 93.0 g, milt weight increased from 3.5 to 5.4 g, sperm density counts decreased from 11.7 × 10⁹ to 10.5 × 10⁹ cells/ml, and spermatocrit decreased from 46.5% to 40.5%. Furthermore, spermatocrit was positively related to haemocytometer counts (R² = .86, p < .001), providing a reliable indicator of sperm density. Differences in sperm kinematics were observed depending on strip-spawning timing after hormonal injection (12 vs. 24 hr) but with no consistent pattern. These sperm quality parameters also did not consistently differ between the no-primer and primer treatments. Considering that each male may be stripped 4–5 times over the 2–3 months spawning season, omitting the primer would reduce animal handling, material costs and labour intensity, while sustaining high-quality sperm production.     

Asset Management of Irrigation Infrastructure – The Approach of Goulburn-Murray Water, Australia

This paper presents a case study of Goulburn-Murray Water's approach to the development and implementation of its asset management program for irrigation infrastructure. The success and effectiveness of asset management is not a matter of technical aspects only, rather it depends on an integrated package of institutional, organisational, technical and financial aspects.     

A systematic survey of loss-of-function variants in human protein-coding genes

Genome-sequencing studies indicate that all humans carry many genetic variants predicted to cause loss of function (LoF) of protein-coding genes, suggesting unexpected redundancy in the human genome. Here we apply stringent filters to 2951 putative LoF variants obtained from 185 human genomes to determine their true prevalence and properties. We estimate that human genomes typically contain ~100 genuine LoF variants with ~20 genes completely inactivated. We identify rare and likely deleterious LoF alleles, including 26 known and 21 predicted severe disease-causing variants, as well as common LoF variants in nonessential genes. We describe functional and evolutionary differences between LoF-tolerant and recessive disease genes and a method for using these differences to prioritize candidate genes found in clinical sequencing studies.