Seagrasses of the north west of Western Australia: biogeography and considerations for dredging-related research: Report of Theme 5 - Project 5.1.2 prepared for the Dredging Science Node

This review was undertaken to identify which seagrass primary producers (species or different functional groups) that collectively cover the bio-geographic range of key primary producers in the north west of Western Australia (NWWA) are most appropriate for the focus of subsequent research into thresholds and indicators of response to dredging-related pressures (i.e. Theme 5). An assessment framework was developed based on six criteria: biogeographic range; ecological relevance (life-history strategy, habitats, natural dynamics and ecological services); current knowledge on thresholds and bioindicators; likelihood that species are sensitive and resilient to dredging related stressors; extent of improvement in applied knowledge; and likelihood of being able to grow seagrass species successfully in mesocosms. For each criterion, one or more assessment metric was developed. These were then used in a hierarchical decision-making process to identify the species most appropriate for the focus of subsequent research. The first step identified those species with the broadest biogeographic range, which were found in the most regions and habitats and which had the greatest ecological significance and prioritised the species for further investigation (Priority 1, 2 and 3). The second step identified species that encompassed a range of sensitivities and resilience to dredging and which, collectively, offered the greatest opportunity to improve our knowledge and understanding of primary producer responses to dredging-related pressures..

Analyzing ion distributions around DNA: sequence-dependence of potassium ion distributions from microsecond molecular dynamics

Microsecond molecular dynamics simulations of B-DNA oligomers carried out in an aqueous environment with a physiological salt concentration enable us to perform a detailed analysis of how potassium ions interact with the double helix. The oligomers studied contain all 136 distinct tetranucleotides and we are thus able to make a comprehensive analysis of base sequence effects. Using a recently developed curvilinear helicoidal coordinate method we are able to analyze the details of ion populations and densities within the major and minor grooves and in the space surrounding DNA. The results show higher ion populations than have typically been observed in earlier studies and sequence effects that go beyond the nature of individual base pairs or base pair steps. We also show that, in some special cases, ion distributions converge very slowly and, on a microsecond timescale, do not reflect the symmetry of the corresponding base sequenc

An Exploratory Study of Police Officers: Low Compassion Satisfaction and Compassion Fatigue

Background: Compassion fatigue, or the physical, mental, and emotional state experienced by professionals that assist others in distress, has been well documented in several caring professions such as nurses, firefighters, and emergency medical technicians. Until the current study, it has only rarely been examined in police samples despite their high rates of stress and suicide which is a likely result of a depletion of compassion satisfaction, or the pleasure an officer gets from relating to and helping others. Aim: This study documents findings from an ongoing study of compassion fatigue amongst a sample of US urban police officers which suggests the possibility of a future risk for high burnout. Conclusion: Very low levels of compassion fatigue were found in the sampled police officers in comparison to what would be expected from the general population. Where compassion fatigue was found in the sampled police, it was significantly correlated to the level of compassion satisfaction. A potential cause for concern is that the incidence of levels of reported compassion satisfaction were also low in the sample (in the bottom quartile compared to the general population). This suggests a possibility of higher numbers of burnout in the future given the role of compassion satisfaction as a buffer against compassion fatigue in policing

Analyzing ion distributions around DNA

We present a new method for analyzing ion, or molecule, distributions around helical nucleic acids and illustrate the approach by analyzing data derived from molecular dynamics simulations. The analysis is based on the use of curvilinear helicoidal coordinates and leads to highly localized ion densities compared to those obtained by simply superposing molecular dynamics snapshots in Cartesian space. The results identify highly populated and sequence-dependent regions where ions strongly interact with the nucleic and are coupled to its conformational fluctuations. The data from this approach is presented as ion populations or ion densities (in units of molarity) and can be analyzed in radial, angular and longitudinal coordinates using 1D or 2D graphics. It is also possible to regenerate 3D densities in Cartesian space. This approach makes it easy to understand and compare ion distributions and also allows the calculation of average ion populations in any desired zone surrounding a nucleic acid without requiring references to its constituent atoms. The method is illustrated using microsecond molecular dynamics simulations for two different DNA oligomers in the presence of 0.15 M potassium chloride. We discuss the results in terms of convergence, sequence-specific ion binding and coupling with DNA conformatio

Sediment burial stress response, bio-indicators and thresholds for a tropical multi-species seagrass assemblage: Report of Theme 5 - Project 5.5.2 prepared for the Dredging Science Node

Changes to the amount of light and burial by the deposition of suspended sediments are presumed to be major mechanisms by which dredging can impact seagrasses. This report presents findings from a controlled burial experiment that aimed to determine the effects of burial by sediments on the growth of two seagrass species found in the northwest of Western Australia (NW WA). The report provides guidance and protocols for the application of the research outputs (e.g. seagrass burial stress:response relationships, sub-lethal and lethal bio-indicators and thresholds) to the prediction, assessment, monitoring and management of dredging programs in NW WA..

Response and recovery of a mixed tropical seagrass assemblage to variation in the frequency and magnitude of light deprivation. Report of Theme 5 - Project 5.5.3 prepared for the Dredging Science Node

The capacity of seagrasses to cope with episodes of light deprivation from overlying turbid waters may not only depend on the absolute quantity of light they receive during that episode, but also on how the light deprivation varies through time. For example, turbidity and therefore light reduction may be relatively constant over the episode or it may fluctuate depending on the frequency of pulsed turbidity events. This report presents findings from a controlled mesocosm experiment that aimed to determine the responses of seagrasses to, and recovery from, differences in the pattern of the delivery of light. The study focussed on two seagrass species found in the northwest of Western Australia (NW WA). The report provides guidance and protocols for the application of the research outputs (e.g. light stress frequency and response relationships, recovery potential, sub-lethal and lethal bio-indicators and thresholds) to impact prediction, monitoring and/or management of dredging programs in NW WA..

Current state of knowledge regarding the effects of dredging-related ‘pressure’ on seagrasses: Report of Theme 5 - Project 5.1.1 prepared for the Dredging Science Node

This review summarises our understanding, from a north west of Western Australia (NWWA) and global perspective, the pressures seagrasses are exposed to from dredging, their tolerance thresholds and responses to dredging related stressors, and the bioindicators of dredging related stressors. From this information, we also identified gaps in our knowledge and areas where environmental management and monitoring approaches could be improved. For this review we used information compiled by the WAMSI Dredging Science Node, which included unpublished data from industry, as well as published reports, articles and books..