Bioaccumulation of Total Mercury and Monomethylmercury in the Earthworm Eisenia Fetida

Bioaccumulation factors (BAFs) for inorganic mercury in earthworms are usually < 1; however, factors up to ～10 have been reported. Little information is available concerning the bioaccumulation of organic mercury in earthworms from actual contaminated soils and thus there has been uncertainty in the risk characterization phase of ecological risk assessments of mercury-contaminated sites. This study was initiated to determine the rate of uptake and bioaccumulation of total mercury (T-Hg) and monomethylmercury (MMHg) in Eisenia fetida from soils which have been contaminated with mercury for approximately 30 years. The study consisted of a 28-day uptake phase in three mercury-contaminated soils and one soil with background concentrations of mercury followed by a 14-day depuration phase in background soil only. Total mercury concentrations in the study soils ranged from 85 to 11,542 μg kg^?1 dry weight soil; MMHg concentrations ranged from 1.12 to 7.35 μg kg^?1 dry weight soil. Time to 90% steady states for T-Hg ranged from 36 to 42 days. A steady state did not occur for any of the MMHg exposures during the 42-day study; estimated time to 90% steady state varied from 97 to 192 days. BAFs for T-Hg ranged from 0.6 to 3.3. BAFs for MMHg ranged from 175 to 249. The BAFs for T-Hg and MMHg were larger in earthworms exposed to the lower contaminated soils and smaller in the higher mercury-contaminated soils. The absolute concentrations of T-Hg and MMHg bioaccumulated in E. fetida, however, were higher in the earthworms exposed to the higher mercury soils and lower in the less mercury-contaminated soils.     

Calf health from birth to weaning. III. housing and management of calf pneumonia

Background

The objective of this study was to describe aspects of case study herds investigated by the Department of Agriculture, Fisheries and Food (DAFF) in which animal welfare incidents occurred and to identify key performance indicators (KPIs) that can be monitored to enhance the Early Warning System (EWS). Despite an EWS being in place for a number of years, animal welfare incidents continue to occur. Questionnaires regarding welfare incidents were sent to Superintending Veterinary Inspectors (SVIs), resulting in 18 herds being chosen as case study herds, 12 of which had a clearly defined welfare incident date. For each study herd, data on six potential KPIs were extracted from DAFF databases. The KPIs for those herds with a clearly defined welfare incident date were studied for a consecutive four year window, with the fourth year being the 'incident year', when the welfare incident was disclosed. For study herds without a clearly defined welfare incident date, the KPIs were determined on a yearly basis between 2001 and 2009.

Results

We found that the late registration of calves, the use of on-farm burial as a method of carcase disposal, an increasing number of moves to knackeries over time and records of animals moved to 'herd unknown' were notable on the case farms.

Conclusion

Four KPIs were prominent on the case study farms and warrant further investigation in control herds to determine their potential to provide a framework for refining current systems of early warning and prevention.     

Enterococcus faecalis senses target cells and in response expresses cytolysin

Many virulent strains of Enterococcus faecalis produce a two-subunit toxin, termed cytolysin. Cytolysin expression is regulated by one of the subunits (CylL(S)') through a quorum-sensing autoinduction mechanism. We found that when target cells are absent, the other subunit (CylL(L)') forms a complex with CylL(S)', blocking it from autoinducing the operon. When target cells are present, however, CylL(L)' binds preferentially to the target, allowing free CylL(S)' to accumulate above the induction threshold. Thus, enterococci use CylL(L)' to actively probe the environment for target cells, and when target cells are detected, allows the organism to express high levels of cytolysin in response.     

Adapting agricultural land management to climate change: a regional multi-objective optimization approach

In several regions of the world, climate change is expected to have severe impacts on agricultural systems. Changes in land management are one way to adapt to future climatic conditions, including land-use changes and local adjustments of agricultural practices. In previous studies, options for adaptation have mostly been explored by testing alternative scenarios. Systematic explorations of land management possibilities using optimization approaches were so far mainly restricted to studies of land and resource management under constant climatic conditions. In this study, we bridge this gap and exploit the benefits of multi-objective regional optimization for identifying optimum land management adaptations to climate change. We design a multi-objective optimization routine that integrates a generic crop model and considers two climate scenarios for 2050 in a meso-scale catchment on the Swiss Central Plateau with already limited water resources. The results indicate that adaptation will be necessary in the study area to cope with a decrease in productivity by 0–10 %, an increase in soil loss by 25–35 %, and an increase in N-leaching by 30–45 %. Adaptation options identified here exhibit conflicts between productivity and environmental goals, but compromises are possible. Necessary management changes include (i) adjustments of crop shares, i.e. increasing the proportion of early harvested winter cereals at the expense of irrigated spring crops, (ii) widespread use of reduced tillage, (iii) allocation of irrigated areas to soils with low water-retention capacity at lower elevations, and (iv) conversion of some pre-alpine grasslands to croplands.     

Identification of low productivity sites for European larch (Larix decidua Miller) in Maine,USA

As silvicultural capital becomes limited, allocation of funds to high quality sites becomes critical and sites with low productivity potential should be avoided. Data collected from 31 plots located in 12 plantations established between 1930 and 1982 throughout central Maine were used to develop a soil-based rule to identify sites having a low productivity potential for European larch in Maine, thereby removing them from consideration for plantation establishment. Stepwise regression and discriminant analyses identified several variables that were associated with site index at an index age of 20 years breast height (SI₂₀): solum thickness, B horizon clay content, and B horizon exchangeable K. Using these variables, a classification rule was developed to classify sites into 2 categories (poor, average SI₂₀=14.7 m; and good, average SI₂₀=17.7 m). Cross-validation demonstrated that the classification functions correctly identified 88% of the poor sites and 81% of the good sites.     

The effect of grazing versus cutting on dry matter production of multispecies and perennial ryegrass‐only swards

Dry matter (DM) production of multispecies swards compared to perennial ryegrass (Lolium perenne; PRG) swards under intensive grazing warrants investigation as it is relatively unknown. A 5 × 2 factorial experiment, with five sward types and two defoliation methods, was used to investigate the effect of grazing versus cutting on dry matter (DM) production of multispecies and PRG‐only swards. Five sward types were established namely: a PRG‐only sward, receiving 250 kg N ha^?1 year^?1 (PRG250), and a PRG‐only sward (PRG90), a two‐species sward with PRG and white clover (Trifolium repens; PRGWC), a six‐species sward (6S) and a nine‐species sward (9S), each receiving 90 kg N ha^?1 year^?1. Cutting plots measured 1.95 × 10 m and grazing plots measured 10 × 10 m. All plots were harvested concurrently every 21–30 days from April‐November for two years (2015 and 2016). A strip from the grazing plots was cut for DM yield determination prior to turning in cattle for grazing. There was an interaction between sward type and defoliation method (p < .01), whereby there was no effect of defoliation method on the PRG‐only swards, however, the annual DM production of PRGWC, 6S and 9S swards reduced under grazing compared to cutting (p < .001; on average 1,929 kg DM/ha lower). Multispecies swards had lower DM production under grazing compared to cutting, while the DM yield of PRG‐only swards was unaffected by defoliation method.