Ecology of epifaunal caridean shrimps in the Hopkins River estuary, and the role of estuaries in the life history of the atyid "Paratya Australiensis" Kemp, 1917 in south-eastern Australia

This study examined the factors affecting the distribution and abundance of epifaunal caridean shrimps in seagrass meadows of the Hopkins River estuary in south-western Victoria, Australia, and investigated the life history patterns of the freshwater Parana australiensis, found for the first time in estuaries. Adult and sub-adult shrimps were surveyed in seagrass meadows along the estuary over two years, and their planktonic larvae were surveyed in adjacent waters. Three species were collected. The marine Palaemon serenus occurred only near the mouth, summer to autumn, in high salinities. The marine/estuarine Macrobrachium intermedium occurred throughout the estuary. Adults were most abundant in late autumn, and least abundant in summer (unlike trends reported in marine meadows). Densities were higher and less variable in downstream meadows. P. australiensis occurred in the upper estuary all year, most abundantly in spring, due to migration from the river after peak discharge. Ovigerous females dominated, while males, showing less migration into the estuary, dominated above estuarine influence. Adults disappeared from the estuary in summer as salinity rose. Breeding period for P. australiensis was briefer in the estuary (September-December) than upstream (July-April). M. intermedium began breeding later in the upper estuary (November/December-March) than in the lower estuary (October-March), probably reflecting a physiological response to lower salinity, rather than an interaction with P. australiensis. No ovigerous P. serenus were found in the estuary. Larvae of P. australiensis and M intermedium occurred abundantly throughout the estuary, but P. serenus larvae did not. P. australiensis was an early coloniser to the plankton after peak discharge (November-December). Larvae concentrated in the deep saline layer at the head of the intruding salt wedge, thus probably maintaining longitudinal position. Diurnal vertical migrations were evident within the salt wedge, and in a deep pool above tidal influence. M. intermedium larvae occurred October-May in the lower estuary and November-April in the upper estuary, peaking in abundance one to two months after P. australiensis. They were associated with low surface flows and surface salinities greater than 10, over an anoxic deeper layer. All three species exhibited extended development of euryhaline larvae in the laboratory. Tolerances and optimal salinities of larvae of the three species reflected their distributions. M. intermedium was the most euryhaline species. P. australiensis larvae were tolerant of higher salinities than juveniles of adults: capable of developing in salinity of at least 15. Most P. australiensis juveniles recruited to the estuary November-December, after which numbers declined dramatically. After settlement, most recruits probably migrated upstream out of the estuary. Two cohorts of M. intermedium recruited to the estuary from larvae in summer (December and February), but some juveniles also migrated from adjacent coastal waters. Post-larval migration was at least as important a determinant of abundance as direct recruitment from estuarine, planktonic larvae in all three species. Distributions among seagrass meadows along the estuary were determined primarily by physico-chemical patterns driven by hydrological changes. Seasonal variations in salinity and temperature were strongly associated with seasonal variations in shrimp abundance. Salinity tolerances of adults of the three species reflected their distribution patterns. Biotic interactions were more important in determining distributions within meadows. P. australiensis, when abundant, were associated with seagrass biomass. M. intermedium were also, but when seagrass was sparsest and least extensive. The two species apparently partitioned the seagrass meadow according to depth in early summer. Laboratory experiments suggested P. australiensis was displaced from deeper water by M. intermedium. Preference for vegetative complexity and competition for position within meadows suggest the underlying importance of predation in regulating shrimp populations. A survey of south-eastern Australian estuaries found P. australiensis larvae abundant in all stable, open, well-developed, salt-wedge estuaries where adults were abundant. Adults were most abundant in low salinities among submerged leafy macrophytes. Reproductive traits of P. australiensis were compared in estuarine and fresh reaches of three rivers. Early in the breeding season, egg size was smaller, and (size-specific) egg number larger in estuaries than upstream. A trade-off between egg size and egg number resulted in no difference in total (size-specific) reproductive investment between locations. Reproductive investment tended to decrease at some locations over the breeding season, and this decrease was a result of decreased egg size in most cases. The decrease in reproductive investment probably reflected reduced food availability for the adult, while the reduced egg size was probably a response to improved conditions for larval development. In the Hopkins River, larger egg size at upstream sites was reflected in larger early stage larvae. Later stage larvae were larger in the estuary, suggesting more favourable conditions for larval development. Allozyme electrophoresis showed the P. australiensis populations in each of the three rivers to be distinct. Allozyme frequencies were not different within the Hopkins River, but upstream and estuarine locations in the Curdies and Gellibrand were different. Although some variation in reproductive traits within catchments may have been due to genotypic differences, trade-offs between egg size and number, and decreases in egg size over summer were probably due to plastic responses to environmental cues. It is proposed P. australiensis inhabits and reproduces in both estuarine and freshwater environments by plastic response to environmental conditions. Recruitment to estuaries is dependent on the presence of suitable adult, littoral habitat, and a stable salt wedge for larval retention. Estuaries are important recruitment sites for P. australiensis, potentially allowing an extra brood each year before riverine recruitment. Estuarine broods could constitute a large part of the total fecundity of P. australiensis females. Euryhaline larvae and estuarine recruitment of P. australiensis suggest marine transport of larvae between estuaries as a possible dispersal mechanism for Paratya species.

The history of distance education in Australia

This article presents a history of distance education in Australia. Australia's large distances and widely distributed population has meant that distance education has been an important part of its history. From the earliest provision of schooling by mail through a series of correspondence schools, both state and federal governments have provided a sound infrastructure to support distance education. Innovative uses of technologies to provide communication and interaction and ease the isolation of distance have also been a feature of Australia's distance education history. The impact of this history is particularly relevant as the Internet and information and communication technologies are changing this field and making distance educators of all institutions and sectors.

Evidence-based mental health nursing in Australia: our history and our future

This paper will develop a discussion related to evidence-based knowledge for mental health nursing, arguing for a historical component to be included in the comprehensive degree programme that will offer significant insights into mental health nursing knowledge from historical information and constructing implications for contemporary practice. Our understanding of the present is clearer by this looking back and forth and by adding meaning (and what the meanings mean) to what historically preceded. It allows the history of psychiatry to be a much more productive, useful, and a continual source of wisdom for the here and now. This blending of past knowledge with contemporary inquiry can offer depth in mental health nursing practices by forming a context for practice for the beginning nurse practitioner.

Book reviews : David Palmer, Ross Shanahan, and Martin Shanahan, eds., Australian Labor history reconsidered

An objective of this collection is to bring the history of the Australian labor movement to international attention. The editors introduce the collection with a brief overview of Australian labor history, emphasizing differences between the Australian and American experiences. The introduction argues that a unique aspect of Australian labor history is “laborism,” which is defined as the central place of the labor movement in Australian culture, as compared with the more marginal position of the labor movement in America. In Australia, this centrality is reflected in the embedding of trade unions and labor in the state through wage-fixing tribunals, a social security system designed to support the families of male wage earners, and the Australian Labor Party's strong links to the trade union movement. The introduction is informative and especially benefits from the insights of David Palmer, an American historian teaching at Adelaide's Flinders University. However, the introduction was apparently written later at the suggestion of an American reader and has thus not been fully integrated into the structure of the book.

The role of sister city relationships in the enhancement of trade : Latrobe City (Australia) and Taizhou (China)

Traditionally the role of Sister City relationships has been a political and cultural one involving local governments across the world. Over the decades this role has been questioned in both its efficacy as well as its
focus. Hundreds of Sister City relationships have developed and in Australia velY few can be said to have produced long term and worthwhile outcomes. New interpretations of the /ill1ctionality of Sister City relationships in Australia (and elsewhere) has resulted and has shifted towards an inclusion of a consideration of the commercial utility of such relationships and not solely cultural (0 'Toole 2001). Today especially with current strong trade relations with China, new models are sought to provide sustainability and long term prospects to such relations. This paper examines the possibility of special sister city relations between
Australian and Chinese cities using their sister city links. Specifically an examination in this paper is undertaken of the City of Latrobe and Taizhou as a case study of interest which provides sustainable trade potential between two strong small medium enterprise (SME) economies.