EFSA BIOHAZ Panel (EFSA Panel on Biologicial Hazards), 2013. Scientific Opinion on the public health hazards to be covered by inspection of meat (solipeds)

A risk ranking process identified Trichinella spp. as the most relevant biological hazard in the context of meat inspection of domestic solipeds. Without a full and reliable soliped traceability system, it is considered that either testing all slaughtered solipeds for Trichinella spp., or inactivation meat treatments (heat or irradiation) should be used to maintain the current level of safety. With regard to general aspects of current meat inspection practices, the use of manual techniques during current post-mortem soliped meat inspection may increase microbial cross-contamination, and is considered to have a detrimental effect on the microbiological status of soliped carcass meat. Therefore, the use of visual-only inspection is suggested for “non-suspect” solipeds. For chemical hazards, phenylbutazone and cadmium were ranked as being of high potential concern. Monitoring programmes for chemical hazards should be more flexible and based on the risk of occurrence, taking into account Food Chain Information (FCI), covering the specific on-farm environmental conditions and individual animal treatments, and the ranking of chemical substances, which should be regularly updated and include new hazards. Sampling, testing and intervention protocols for chemical hazards should be better integrated and should focus particularly on cadmium, phenylbutazone and priority “essential substances” approved for treatment of equine animals. Implementation and enforcement of a more robust and reliable identification system throughout the European Union is needed to improve traceability of domestic solipeds. Meat inspection is recognised as a valuable tool for surveillance and monitoring of animal health and welfare conditions. If visual only post-mortem inspection is implemented for routine slaughter, a reduction in the detection of strangles and mild cases of rhodococcosis would occur. However, this was considered unlikely to affect the overall surveillance of both diseases. Improvement of FCI and traceability were considered as not having a negative effect on animal health and welfare surveillance

Histopathology of oedema in pearl oysters Pinctada maxima

In October 2006, severe mortalities (80 to 100%) were reported in pearl oyster Pinctada maxima production farms from Exmouth Gulf, Western Australia. Only P. maxima were affected; other bivalves including black pearl oysters P. margaratifera remained healthy. Initial investigations indicated that the mortality was due to an infectious process, although no disease agent has yet been identified. Gross appearance of affected oysters showed mild oedema, retraction of the mantle, weakness and death. Histology revealed no inflammatory response, but we did observe a subtle lesion involving tissue oedema and oedematous separation of epithelial tissues from underlying stroma. Oedema or a watery appearance is commonly reported in published descriptions of diseased molluscs, yet in many cases the terminology has been poorly characterised. The potential causes of oedema are reviewed; however, the question remains as to what might be the cause of oedema in molluscs that are normally iso-osmotic with seawater and have no power of anisosmotic extracellular osmotic regulation

Inland acid sulfate soils in the floodplain wetlands of the Murray- Darling Basin: regional occurrence using rapid methods and the impacts of reflooding on water quality

A full appreciation of the extent and significance of acid sulfate soils (ASS) in Australia's inland environments has only recently been realised, in contrast to ASS in Australia’s modern-day coastal zones, which have been well studied over the last four decades. Investigations into the inland ASS systems of the Murray-Darling Basin (MDB), Australia's largest river system, did not occur with any intensity prior to 2006. A number of key knowledge gaps exist concerning the occurrence, properties and behaviour of inland ASS systems in the MDB. These knowledge gaps, combined with the ecological and economic significance of the MDB, and the potential for environmental and infrastructure degradation through ASS acidification, provided the incentive for this research project. The main objective was to advance the understanding of inland ASS in the MDB. This was achieved by answering two key research questions: What is the prevalence and distribution of ASS with hypersulfidic and sulfuric materials in the floodplain wetlands of the MDB? What are the dominant geochemical pathways taken following freshwater reflooding of inland ASS containing sulfuric materials and the timescales of impact? The first research question was answered through a regional assessment of ASS in the MDB and represents the most extensive estimate of the basin-wide occurrence of inland ASS in the floodplain wetlands of the MDB thus far. As part of a government funded initiative, regional environmental officers collected approximately 7200 wetland soil samples, which were then submitted for soil incubation tests. The large number of samples requiring analysis, and the need for the rapid and robust classification of hypersulfidic materials led to the development of a simplified incubation method (see Chapter 2). This method was found to offer significant improvements over existing incubation methods. Firstly, the use of chip-trays as incubation vessels was found to offer many advantages in terms of transport, storage and analysis of soil samples compared with soil-slabs. Secondly, the conditional extension of the incubation period resulted in the accurate classification of slowly acidifying hypersulfidic materials whist maintaining a minimal test length. Following its development, the simplified incubation method was used to assess the acidification potential of ca. 2500 profiles in over 1000 wetlands located throughout the MDB (see Chapter 3). The results of pH measurements made before and following soil incubation were used to estimate the prevalence and distribution of sulfuric and hypersulfidic ASS materials across the MDB. A total of 238 floodplain wetlands, representing 23% of the total wetlands assessed, were found to contain soils that severely acidified (pH < 4) when oxidised. The number of these soils, the majority of which are likely to be hypersulfidic ASS materials, indicates that inland ASS are prevalent in the floodplain wetlands of the MDB. As a result, the potential existence of inland ASS should be a key consideration for wetland management plans in any floodplain wetland located in the MDB. The distribution of ASS materials in the MDB was investigated by dividing it into 13 geographical regions, whose boundaries roughly followed hydrological catchment boundaries. The distribution of acidification hazard was non-uniform throughout the MDB. The geographical regions with the greatest acidification hazard were in the southern MDB, downstream of the Murray-Darling confluence, and in catchments on the southern side of the Murray River channel in Victoria. The non-uniform distribution of ASS throughout the MDB has implications for the successful management of inland ASS in the MDB, whereby regions presenting the greatest acidification should receive much greater attention. Overall, the development of the simplified incubation method and the extensive broad-scale assessment of ASS in the MDB provided policy makers with a valuable screening tool, helping them to identify priority wetlands and regions that required more detailed IASS investigations. The second research question was answered through two focused field studies, which applied in situ sampling and monitoring techniques to investigate the geochemical behaviour of severely acidified inland ASS materials following reflooding by freshwater. The reflooding of severely acidified inland ASS by freshwater has been suggested as a viable remediation method. However, this hypothesis is based on observations made in coastal ASS systems following reflooding by sea water and had not yet been extensively documented in freshwater systems at the commencement of this research project. In the first study, equilibrium dialysis membrane samplers were used to investigate in situ changes to soil acidity and abundance of metals and metalloids following the first 24 months of restored subaqueous conditions (see Chapter 4) In the second study, mesocosms were installed in situ to simulate reflooding and the key geochemical pathways were documented through continuous in situ redox monitoring and the use of in situ soil solution samplers (see Chapter 5). In both studies, the strongly buffered low pH conditions of the oxidised sulfuric materials and the limited supply of external alkalinity in freshwater systems meant that soil acidity persisted for more than 24 months following reflooding. The persisting low pH conditions, along with insufficiently reducing redox conditions, and competitive exclusion by iron(III)-reducing bacteria were suspected to inhibit sulfate reduction. Following the eventual removal of the above limitations it is hypothesised that the lack of readily available soil organic carbon will further inhibit sulfate reduction. Under continued absence of net in situ alkalinity production, via the formation of reduced inorganic iron and sulfur species, observed trajectories indicate that neutralisation of soil acidity may take several years. Small increases in soil pH confined to within 10 cm of the soil-water interface were observed after 24 months of subaqueous conditions. Substantial decreases in the concentrations of some metals and metalloids were observed to coincide with the small increases in soil pH, most likely owing to lower solubility and sorption as a consequence of the increase in pH. In the acidic porewaters, aluminium activity was consistent with a control by a solid phase aluminium species with stoichiometry Al:OH:SO4 (e.g. jurbanite). In the same acidic porewaters, iron and sulfate activity were regulated by the dissolution of natrojarosite. Following the establishment of reducing conditions, the reductive dissolution of accumulated natrojarosite and schwertmannite phases was responsible for large increases in total dissolved iron. The differing physical properties and chemical characteristics, such as stored acidity and contaminant concentrations, of dominantly clayey soils and dominantly sandy soils, led to contrasting impacts on the transport of solutes following reflooding (diffusive versus advective flow, respectively) and timescales of recovery. A number of key geochemical processes influencing the porewater concentrations of acidity, iron, aluminium, and metals and metalloids following reflooding by freshwater were observed in these severely acidified inland ASS systems. These physical and geochemical processes were summarised in two conceptual hydrogeochemical process models, which were used to distil complex information and convey it in a format readily understandable to a non-ASS specialist audience.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Biological Sciences, 2015

Diseases of pearl oysters and other molluscs: A Western Australian perspective

Mollusc culture, particularly the cultivation of pearl oysters, is an important component of the aquaculture industry in Western Australia. As a result, there has been a long-term investment in surveys of commercial mollusc species for potential diseases of concern. A number of pathogens, particularly haplosporidans, identified within wild-stock shellfish have the potential to adversely affect mollusc populations. Others pose risks for translocations associated with aquaculture. The microsporidan Steinhausia mytilovum (Field), found in ova of the blue mussel Mytilus galloprovincialis (Lamarck), poses intriguing questions about the origin and dispersal of its host

Skeletal myopathy in juvenile barramundi, Lates calcarifer (Bloch), cultured in potassium-deficient saline groundwater

Saline groundwater is being pumped from a number of locations in rural Western Australia to prevent secondary salinity impacting farmland, rural infrastructure and areas with high conservation value. Aquaculture may offset the costs of groundwater pumping, and the suitability of groundwater for finfish aquaculture is being assessed through bioassays. There are marked spatial variations in the ionic composition of saline ground water in Western Australia and this paper describes two bioassays investigating a saline, potassium-deficient water source that resulted in mortalities in juvenile barramundi, Lates calcarifer (Bloch). Histopathological examination revealed severe degeneration and necrosis of skeletal muscles, marked hyperplasia of branchial chloride cells and renal tubular necrosis. Clinical chemistry findings included hypernatraemia and hyperchloridaemia of the blood plasma and lowered muscle potassium levels. It is concluded that the principal cause of death was skeletal myopathy induced by low water potassium levels

Porewater geochemistry of inland acid sulfate soils with sulfuric horizons following postdrought reflooding with freshwater

Following the break of a severe drought in the Murray-Darling Basin, rising water levels restored subaqueous conditions to dried inland acid sulfate soils with sulfuric horizons (pH <3.5). Equilibrium dialysis membrane samplers were used to investigate in situ changes to soil acidity and abundance of metals and metalloids following the first 24 mo of restored subaqueous conditions. The rewetted sulfuric horizons remained severely acidified (pH ∼4) or had retained acidity with jarosite visibly present after 5 mo of continuous subaqueous conditions. A further 19 mo of subaqueous conditions resulted in only small additional increases in pH (∼0.5-1 pH units), with the largest increases occurring within the uppermost 10 cm of the soil profile. Substantial decreases in concentrations of some metal(loid)s were observed with time most likely owing to lower solubility and sorption as a consequence of the increase in pH. In deeper parts of the profiles, porewater remained strongly buffered at low pH values (pH <4.5) and experienced little progression toward anoxic circumneutral pH conditions over the 24 mo of subaqueous conditions. It is proposed that low pH conditions inhibited the activity of SO₄²-reducing bacteria and, in turn, the in situ generation of alkalinity through pyrite production. The limited supply of alkalinity in freshwater systems and the initial highly buffered low pH conditions were also thought to be slowing recovery. The timescales involved for a sulfuric horizon rewetted by a freshwater body to recover from acidic conditions could therefore be in the order of several years.Nathan L. Creeper, Paul Shand, Warren Hicks, and Rob W. Fitzpatric

Behaviour of iron, aluminium and other selected metals following the rewetting of inland acid sulfate soils containing sulfuric material

Also published as: Geological Survey of Finland, 2012; Guide 56:26-28Creeper, N. L., Shand, P., Fitzpatrick, R. W. and Hutson, J.http://projects.gtk.fi/7iassc/conference/programme/presentation.htm

Geochemical processes following freshwater reflooding of acidified inland acid sulfate soils: an in situ mesocosm experiment

Abstract not available.Nathan L. Creeper, Warren S. Hicks, Paul Shand, Rob W. Fitzpatric