Current trends in the study of molluscan diseases

The study of molluscan diseases has a long history. The first publication on the redial stages of a trematode appeared in the 18th century; early papers on molluscan phagocytosis appeared in the last half of the 19th century and yet much work published before about 1975 does not appear in electronic abstract databases and is effectively “lost”. By contrast, a recent search of a leading abstract database for the terms “mollusc” and “disease” shows that the number of publications has exploded in the last eight years and the exponential trend looks set to continue. Much of the increase has been driven by the introduction of molecular technologies, the rediscovery that the immunology of invertebrates generally is a rich hunting ground for new biochemical defence systems and thus potential medical breakthroughs and the desire to publish multiple papers from the same project. As this publication trend continues, it will become increasingly difficult to be knowledgeable on all aspects of molluscan diseases and considerable specialisation is inevitable. It is not only our knowledge about known mollusc diseases that has grown, since new diseases continue to be reported as: aquaculture becomes more intensive; the Asia/Pacific regional skills base develops; and international reporting becomes more accurate. Transfer of disease between jurisdictions is also becoming more rapid as products are sent live around the world both as broodstock and for human consumption. Thus, the work of the Network of Aquaculture Centres in the Asia and the Pacific and the Food and Agriculture Organization of the United Nations in awareness raising and skills development will continue to make an impact. It is inevitable that, as the initial work on mollusc diseases developed around shellfish growing areas in Europe and America, the next generation of molluscan disease experts will be based in the Asia and the Pacific region

A checklist of the parasites of New Zealand fishes including previously unpublished records

An earlier checklist of parasites of New Zealand fishes (Hewitt & Hine 1972) listed 356 parasite species from 143 fish species, most (78%) of which were reported in the 25 years up to 1972. Many of these parasites were reported by parasitologists working specific groups, such as blood parasites (Laird 1951, 1952, 1953), myxosporeans (Meglitsch 1960), digeneans (Manter 1954), monogeneans (Dillon & Hargis 1965a & b, 1968), cestodes (Alexander 1963) and nematodes (Brunsdon 1956). The checklist of Hewitt & Hine (1972) is here updated to 1999. The species reported in the earlier checklist are listed here, but, for the sake of brevity, the references to those species are not included. The fish species listed here each have a code that indicates whether they are freshwater (F), shallow water (SW), inshore shelf (I), central to outer shelf (C), or outer shelf/oceanic (0), whether they are agnathans (lampreys and hagfishes) (A), elasmobranchs (sharks and rays) (E), holocephalans (ghost sharks) (H), or teleosts (T), and whether they are pelagic (P) or demersal (D). Each fish species then has its own number. This system has also been applied to the listed fishes from Hewitt & Hine (1972), and the taxonomy of fishes listed in Hewitt & Hine (1972) has been updated. This paper firstly lists the hosts and their parasites. Hosts are in most cases listed alphabetically by genera within each host group (elasmobranchs, teleosts, etc) and within pelagic and demersal groups. Where the name is followed by "(see Hewitt & Hine 1972)", this indicates that all the records occur in the earlier checklist. Where "(see also Hewitt & Hine 1972)" is used, this means that some of the records occur in the earlier checklist, and some are new. A list of the parasites and the hosts in which they occur is then given

Assessment of the risks associated with the release of abalone sourced from Abalone hatcheries for enhancement or marine grow out in the open ocean areas of WA

The virus that causes Abalone Viral Ganglioneuritis (AVG) is considered to be exotic to Western Australia (WA). The known distribution includes Victoria, Tasmania and Taiwan. There are a number of known strains of the virus; Tasmanian strains do not (to date) cause mortalities in wild abalone (but do so in farms and processing facilities). Victorian and Taiwanese strains cause high mortalities in wild abalone. Despite active surveillance, the virus has not been found in NSW, South Australia or Western Australia but there is a low likelihood that WA specific strains may exist undetected. The risk posed by AVG virus occurring in juveniles sourced from hatcheries in WA and translocated to the open ocean in southern Western Australia either for stock enhancement (reseeding) or for marine grow-out (sea-ranching) purposes has been assessed using standard risk assessment methodology with the outputs having been independently reviewed. While the likelihoods of the AVG virus occurring in the hatchery range from “negligible to “low” should no additional management measures be applied, the consequences of detection (including biological, economic and environmental) are generally “High” and in two cases the resultant risks were “unacceptable” with just the current legal management requirements. Given that the initial risks associated with oceanic deployment of abalone were assessed as Moderate to High, additional formal management intervention is required to reduce these to acceptable levels. The primary concern is that the virus could become established in a hatchery facility and then be more likely to infect wild stock through the release of hatchery released juveniles into the oceanic waters. The likelihood of this outcome occurring has been assessed as very low if the suggested hatchery management measures that could be applied to mitigate the risk to an acceptable level are adopted. Protocols are in place to ensure that any emergence of AVG in a hatchery would be detected. If the virus was ever detected in the hatchery the water supply should be immediately shut down. This can be done using existing legislation (FRMA r177(2) so there is no legislative impediment to limiting effects of a disease outbreak in a hatchery). The placement of grow out structures and juvenile releases could also be planned in a manner to both minimise the likelihood of transmission to wild stocks and limit the spread of any infection

Pilchard Herpesvirus in Australia 1995-1999

Two epizootics have occurred in populations of the Australasian pilchard Sardinops sagax neopilchardus in waters of southern Australia. The first occurred between March and September 1995. It is thought to be the largest fish kill ever recorded and is also unique in the geographic extent of the mortalities. The economic loss attributed to the 1995 mortality event was in excess of A$12 million. The second occurred in 1998-1999 when approximately 60$ 15 million in Western Australia alone (Gaut, 2001). In 1995 mortalities occurred along more than 5000 km of the Australian coastline (Fig. 1) and also affected pilchards in New Zealand. The disease front spread from its origin in South Australia at about 30 km/day, often against prevailing currents and was not impeded by storm events. Thus it was not caused by planktonic toxins/pathogens. Likewise, there was no consistent association of the mortalities with environmental parameters such as temperature or salinity

Ornamental fish testing project

Biosecurity Australia commissioned a program of testing of goldfish, cichlids, gouramis and livebearers in quarantine. These species were identified as high risk in the 1999 Import Risk Analysis on Live Ornamental Finfish. In the program reported on here, these species were targeted for diagnostic testing when more than 25% of fish in a quarantine tank died during the quarantine period. Diagnostic testing usually involved post mortem, histology and bacteriology with provision for further confirmatory diagnosis as required. Participating diagnostic laboratories in Queensland, New South Wales, South Australia and Victoria were provided with details of basic disease testing procedures and requirements to ensure a consistent approach across all states. Procedures were agreed with AQIS and established nationally to supply targeted fish to the testing laboratories. One hundred cases were investigated from the five states. Victoria ha d the most submissions (43), followed by Queensland with 29 and Western Australia with 15. A bacterial cause was diagnosed in 26 cases and in 13 of these cases the bacterium was Aeromonas hydrophila or Aeromonas sp. 41 diagnoses of protistan and metazoan parasites were made and of these the greatest number were Monogenea (14 cases). There were eight reports of fungal involvement including seven cases of epizootic ulcerative syndrome (EUS). Viral aetiologies were listed in seven submissions. These included four cases of iridovirus in cichlids and one of haematopoietic necrosis virus in goldfish (GFHNV). Stress was reported as a contributing factor in at least 11 submissions. The large number of diagnoses of EUS, all in gouramis, and the four cases of iridovirus in cichlids is of concern. Surprisingly iridovirus was not diagnosed in gouramis during the survey despite most previous diagnoses of this virus in ornamental fish in Australia being in gourami

The Wisdom of Samuel Johnson

Aside from his famous Dictionary, Samuel Johnson (1709-1784) is well-known for" London: APoem,"" The Rambler,"" The Idler,\u27 and"Rasselas." This essay will deal mainly with his popularwritings in"The Rambler,"" The Adventurer,"" The Idler" and" The Sermons." It will also presentselections from these writings in an attempt to show that Johnson\u27s wisdom is still applicable toproblems that humans have always faced and still confront today. Though his behavior and beliefshave often been described as odd by some witnesses, he was in essence a highly moral man whodescribed the world with a clear vision, seldom matched by other writers in the English language,except perhaps Shakespeare. So in many of his writings, such as" The Rambler," his stated purposewas to" clear it (The English language) from (sic) colloquial barbarisms, licentious idioms, andirregular combinations" (Rambler 208). This was possibly Johnson\u27s language experiment and a boldone to undertake---much like his Dictionary

Melville\u27s "The Confidence-Man"

This paper will explore one of Melville\u27s least-known novels:"The Confidence-Man: His Masquerade."Of course Melville\u27s greatest, best-known and largely unread masterpiece is"Moby-Dick,"the novel that everyone intends to read, but never really gets to or finishes; it is widely considered a`difficult\u27book. If this can be said of"Moby-Dick"then"The Confidence-Man"is an almost impossible book. It was Melville\u27s last novel and the great merit of this work is its characterization of the American people in the 1850s. Admittedly, Melville was an embittered writer by this time; but he was too much of a philosopher not to be truthful about Americans and their behaviors and attitudes. His people in this novel accurately portray some of the strengths and weaknesses of Americans, at that time and this; these traits are still relevant to an understanding of America and Americans; this is perhaps truer today than in 1857

Virus-like particles associated with marine mussel mortalities in New Zealand

Green-lip mussel Pema canaliculus spat (15 to 30 mm length) in the outer Marlborough Sounds, New Zealand, suffered 50 to 100% mortality during January to April 1994 (summer/autumn) following thinning and reseeding of the mussel lines by farmers. Adult mussel mortalities of 2 to 5 % continued from February to early May 1994. Histological examination showed extensive haemocytosis and multifocal liquefaction necrosis of interstitial cells, basal cells and digestive tubule epithelial cells. Sloughed pyknotic or karyolytic digestive tubule epithelial cells formed characteristic rounded granular bodies 10 to 15 μm diameter both in digestive tubules and free in lesions . No viral inclusion bodies were observed. Ultrastructural examination showed highly modified rough endoplasmic reticulum associated with small, 25 to 45 nm diameter, electron- dense uncoated virus-like particles Identical cell damage and virus-like particles were subsequently found in monbund adult (75 to 110 mm length) P canaliculus and stunted (25 to 4 7 mm length) subt1dal Mvtilus galloprovincialis from the same area. Following purfication of extracts of the moribund spat by isopycnic centrifugation in CsCJ, large numbers of 25 nm diameter, unenveloped, virus particles were seen by electron microscopy. These particles had a density of 1.364 g cm- 3 A broad band at a density expected for enveloped particles (1.21to1.24 g cm 1 ) was also observed but contained few virus-like particles. Cell damage and mussel mortalities are thus likely due to a small unenveloped virus

A Review of Hybrid Manufacturing

In recent years the combination of laser-based Additive Manufacturing and Computer Numerical Controlled (CNC) machining has become increasingly popular, with several machine tool manufacturers exhibiting products based on different machine tool configurations. This technology, widely known as Hybrid Manufacturing, generally exploits Directed Energy Deposition processes using powder feedstock that is fed into a melt pool created by a laser. Although Directed Energy Deposition processes predate powder bed fusion Additive Manufacturing (at least in terms of coating and repair applications), commercialization of Hybrid Manufacturing systems is still very much in its infancy. However, they do offer clear advantages, combining a high deposition rate together with the accuracy and surface finish associated with machining. This paper presents the history of the development of Hybrid Manufacturing Systems (HMS), dating back from work undertaken in the mid 1990s through to the present day. The relative merits of different material deposition approaches are compared and some of the key technical challenges which remain are highlighted and discussed.Mechanical Engineerin