Peter Speldewinde

A relationship between environmental degradation and mental health in rural Western Australia.

Australia is currently experiencing a process of escalating ecosystem degradation. This landscape degradation is associated with many outcomes that may directly or indirectly impact on human health. This study used a Bayesian spatial method to examine the effects of environmental degradation (measured as dryland salinity) on the mental health of the resident rural population. An association was detected between dryland salinity and depression, indicating that environmental processes may be driving the degree of psychological ill-health in these populations.

Dryland Salinity and Ecosystem Distress Syndrome: Human Health Implications

Clearing of native vegetation for agriculture has left 1.047 million hectares of southwest Western Australia affected by dryland salinity, and this area may expand up to a further 1.7–3.4 million hectares if trends continue. Ecosystems in saline-affected regions display many of the classic characteristics of Ecosystem Distress Syndrome, one outcome of which has not yet been investigated in relation to dryland salinity: adverse human health implications. This article seeks to review existing information and identify potential adverse human health effects. Three key potential impacts on human health resulting from dryland salinity are identified: wind-borne dust and respiratory health; altered ecology of the mosquito-borne disease Ross River virus; and mental health consequences of salinity-induced environmental degradation. Given the predicted increase in extent and severity of dryland salinity over coming decades, adverse outcomes of salinity are likely to be further exacerbated, including those related to human health. There is a clear need to investigate the issues discussed in this review and also to identify other potential adverse health effects of dryland salinity. Investigations must be multidisciplinary to sufficiently examine the broad scope of these issues. The relationship between human health and salinity may also be relevant beyond Australia in other countries where secondary soil salinization is occurring.

Is There an Association between Dryland Salinity and Ross River Virus Disease in Southwestern Australia

Land use change has the potential to cause severe ecosystem degradation and drive changes in disease transmission and emergence. Broadscale clearing of native vegetation for agriculture in southwestern Australia has resulted in severe ecosystem degradation, which has been compounded by the subsequent development of large areas of dryland salinity. The mosquito-borne disease, Ross River virus (RRV), has been noted as a potential adverse human health outcome in these salinity affected regions. The association between dryland salinity and RRV disease was therefore tested by undertaking a spatial analysis of disease notification records using standard and Bayesian techniques. To overcome inherent limitations with notification data, serological RRV antibody prevalence was also investigated. Neither method revealed a significant association with dryland salinity, however, the spatial scale imposed limited the sensitivity of both studies. Thus, further multidisciplinary studies are required to overcome these limitations and advance understanding of this ecosystem health issue, particularly using variables that can be investigated on a finer scale.

The Hidden Health Burden of Environmental Degradation: Disease Comorbidities and Dryland Salinity

Previous studies have linked poor mental human health with environmental degradation, but none have assessed additional diseases that may co-exist with these mental disorders. In previous work, depression was found to be associated with a major form of environmental degradation; dryland salinity. However, little is known about diseases co-morbid with depression in this environmental setting. In rural Australia, dryland salinity is a major form of environmental degradation contributing widely to deterioration and non-viability of farmland. Using georeferenced health record data, Bayesian spatial methods were used to determine the relationship between dryland salinity and a range of human health outcomes. Initial modelling found an increased relative risk for asthma, suicide and ischaemic heart disease in relation to dryland salinity (adjusted for Indigenous and socio-economic status). However, in this follow-up study, a further evaluation of the role of co-morbidities in this population revealed that: (i) the presence of depression was consistently linked to residence in areas with high salinity and (ii) the association of asthma, suicide and heart disease with salinity was most likely attributable to the co-morbidity of the conditions with depression. Given the predicted increase in dryland salinity and the elevated relative risk of depression in impacted areas, the relative risk of the co-morbid conditions can be expected to increase in rural areas in the future, further adding to the burden of disease associated with environmental degradation.

Is restoring an ecosystem good for your health

Abstract It is well known that the degradation of ecosystems can have serious impacts on human health. There is currently a knowledge gap on what impact restoring ecosystems has on human health. In restoring ecosystems there is a drive to restore the functionality of ecosystems rather than restoring ecosystems to ‘pristine’ condition. Even so, the complete restoration of all ecosystem functions is not necessarily possible. Given the uncertain trajectory of the ecosystem during the ecosystem restoration process the impact of the restoration on human health is also uncertain. Even with this uncertainty, the restoration of ecosystems for human health is still a necessity.

Public Health Perspectives on Water Systems and Ecology

Human health is directly linked to ecosystem functioning, including the dynamics within wetlands. Wetlands can act to initiate or mitigate biological and chemical contamination. In order to assess the potential health risk, investigations focus on potential exposure pathways and evidence that exposure events are actually linked to adverse health effects. This chapter provides a brief introduction to the principals of health risk assessment in relation to wetlands.

Customary and recreational fishing pressure: large-bodied fish assemblages in a tropical, intermittent Australian river

Permanent waterholes in intermittent rivers of northern Australia support a diverse piscifauna and are popular areas for customary and recreational fishing. The present preliminary study explored the perception that fishing reduces the abundance of targeted, large-bodied species that become restricted to disconnected waterholes during the distinct dry season. River sites in the Fitzroy River catchment, Western Australia, could be clearly classified as experiencing either high or low fishing pressure by using metrics of human ‘accessibility’. The abundance of Hephaestus jenkinsi and Lates calcarifer, targeted by both recreational and customary fishers was highly correlated with accessibility and showed a negative relationship with fishing pressure. Non-target species showed no discernible trend. We estimated that 38% of river length remains subject to relatively low fishing pressure. These preliminary relationships suggest that fish harvest can potentially alter the structure of fish assemblages in disconnected habitats. The potential impact of fishing on the sustainability of fish populations is, most likely, greatest for non-diadromous species and will become more apparent with increasing distance from recolonisation sources. Combining management techniques that maintain recolonisation and recruitment potential with traditional fisheries management strategies (e.g. bag and size limits) presents a suitable approach to mitigate the effects of fish harvesting from tropical intermittent rivers.

Predicting arboviral disease emergence using Bayesian networks: A case study of dengue virus in Western Australia

A Bayesian Belief Network (BBN) for assessing the potential risk of dengue virus emergence and distribution in Western Australia (WA) is presented and used to identify possible hotspots of dengue outbreaks in summer and winter. The model assesses the probabilities of two kinds of events which must take place before an outbreak can occur: (1) introduction of the virus and mosquito vectors to places where human population densities are high; and (2) vector population growth rates as influenced by climatic factors. The results showed that if either Aedes aegypti or Ae. albopictus were to become established in WA, three centres in the northern part of the State (Kununurra, Fitzroy Crossing, Broome) would be at particular risk of experiencing an outbreak. The model can also be readily extended to predict the risk of introduction of other viruses carried by Aedes mosquitoes, such as yellow fever, chikungunya and Zika viruses.

Low level off-road vehicle (ORV) traffic negatively impacts macroinvertebrate assemblages at sandy beaches in south-Western Australia

Off-road vehicle use is arguably one of the most environmentally damaging human activities undertaken on sandy beaches worldwide. Existing studies focused on areas of high traffic volumes have demonstrated significantly lower abundance, diversity and species richness of fauna in zones where traffic is concentrated. The impact of lower traffic volumes is unknown. This study aimed to investigate the impacts of relatively low-level vehicle traffic on sandy beach fauna by sampling invertebrate communities at eight beaches located in south-western Australia. We found that even low-level vehicle traffic negatively impacts the physical beach environment, and consequently, the ability of many species to survive in this habitat in the face of this disturbance. Compaction, rutting and displacement of the sand matrix were observed over a large area, resulting in significant decreases in species diversity and density, and measurable shifts in community structure on beaches that experienced off-road vehicle traffic. Communities at impact sites did not display seasonal recovery as traffic was not significantly different between seasons. Given a choice between either reducing traffic volumes, or excluding ORV traffic from beaches, our results suggest that the latter would be more appropriate when the retention of ecological integrity is the objective.

Environmental Correlates of Mental Health Measures for Women in Western Australia

A recent study in Western Australia identified area level associations between soil salinisation and hospital admissions for depression. Our study assessed the quantitative relationship between mental health measures at the individual level and location specific environmental measurements on salinity, as well as two other indicators of environmental degradation and change: land surface temperature and normalised difference vegetation index, a proxy for rainfall. Location-specific environmental measurements were linked to individual mental health scores of women in three age cohorts from the Australian Longitudinal Study on Women’s Health using a geographic information system. Bayesian geostatistical linear regression models were developed to assess associations between environmental exposures and mental health scores of women. In contrast to previous studies using area level measures, our study found no associations between individual level measurements of mental health scores for women in south-west Western Australia and salinity, LST or NDVI.