The thesis consists of seven Sections. Each Section contains a set of published papers, reports or chapters which describe epidemiological aspects of the Cerebral Palsies (CPs). These have, in the main, made use of of the Western Australian Cerebral Palsy Register. Several of the chapters are from a recent book (Stanley and Alberman, 1984), which was an invited monograph in a series published jointly by Spastics International Medical Publications and Blackwells, Oxford. The published work in each Section is introduced and moulded together by text with the aim of making it flow as a composite whole. The numbers and rates differ between papers as the register is continually being updated and recent figures are more accurate and complete than in earlier publications. The Register was established in 1977, with the aims of being basically descriptive: to provide accurate numerator data on the major cause of childhood motor handicap. In addition it was planned to utlisie the data base as a population sampling frame for epidemiological studies searching for causes of the CPs. It is now an ongoing collection and it is the only population-based Cerebral Palsy Register in Australia. Four others exist in the world, one in Denmark (Hansen, 1960; Glenting, 1976), one in Sweden (Hagberg et al., 1975a, 1975b, 1976), one in County Cork, Ireland (Cussen et al., 1978), and one in Newcastle-Upon-Tyne in UK (Hey, personal communication). It is of considerable current interest, as paediatric research is expanding into the causes of childhood handicaps generally, and perinatal researchers are keen to monitor the trends of major handicap in relation to changes in perinatal care.

[Truncated abstract] In the crop growing areas of Western Australia, two economically important weed species, Lolium rigidum Gaud. (annual ryegrass) and Raphanus raphanistrum L. (wild radish), have evolved widespread herbicide resistance to multiple chemistry groups. Consequently, grain growers in the region have adopted an integrated approach to weed management that includes many non herbicide tools, however many more are needed as these weed species become increasingly more difficult to control. This thesis examines, in a series of field trials carried out in the Western Australian crop growing area, the potential for weed seed predation of annual ryegrass and wild radish by naturally occurring granivores as a new weed management tool for grain growers . . . The study discusses the implications of these results with the view to manipulating predation of weed seed through agricultural management practices. Ants were shown to be the dominant seed predator in this environment, especially in the centre of fields. The study has identified that the ant species Melophorus turneri (Forel), Monomorium rothsteini (Forel), Pheidole hartmeyeri (Forel) and Rhytidoponera metallica (Smith) are potential biological control agents for annual ryegrass seeds while P. hartmeyeri was identified as the only species suitable for biological control of wild radish seed pods. Ants were found to be sensitive to disturbance and some to crop residue type and these effects are discussed in relation to seed removal. This study of weed seed predation in agricultural fields is the most complete in this environment and can be used to inform further work in this area. It has identified that naturally occurring granivores can be used as a weed management tool.

[Truncated abstract] Background: Genetic epidemiology draws on the mechanisms of heredity and the reproductive characteristics of populations to formulate methods to investigate the role of genetic factors and their interaction with the environment in disease aetiology. Asthma and atopy are complex genetic disorders and are among the most common diseases to affect the developed world. Twin studies provide an elegant means of disentangling genetic and environmental contributions to the aetiology of conditions that have a significant impact on the health of the general population in ways that cannot be achieved by any other study design, by comparing disease frequency in monozygotic (MZ) or identical twins, who share 100% of their genes with that in dizygotic (DZ) or non-identical twins who share, on average, 50% of their genes. Twin-family studies allow the complete partitioning of phenotypic variation into components representing additive genetic, dominance, shared environment and non-shared environment. ... For twin family data, the best fitting model was the one which included additive genetic effects and either genetic dominance or shared sibling environment, and that shared family environment was not important. With respect to asthma in WA twin families, there are no reasons to conclude that the EEA is not valid. Conclusions: The WA Twin Register is the first population-based register of childhood multiples to be established in Australia, and the WATCH study is one of only a few population-based twin-family studies in the world. Families who participated in the WATCH study were no different from non-participants with respect to social class and there was no difference in the prevalence of DDA in WATCH study twins and either their singleton siblings or the general population of WA children. Results from the GEE models replicate those found in numerous studies from many different countries. The BUGS models developed have been shown to produce consistent results with both simulated and real data sets and offer alternative methods of analyzing twin and twin-family data. By including an extra term in the partitioning of the variance to account for the environment effect of being a MZ twin, a numerical value is calculated for the difference in MZ and DZ correlation with respect to the phenotype examined, which allows the validity of the EEA to be directly assessed.

The spotted minnow, Galaxias maculatus has a widespread southern hemisphere and circum-polar distribution including south-western and south-eastern Australia. It was sampled at monthly intervals over 12-18 months, by seine and plankton netting at three localities including a freshwater lake, Moates Lake, and two intermittently flowing, naturally saline rivers, the Jerdacuttup and the Oldfield rivers on the south coast of Western Australia. The resulting data provided an opportunity to describe the biology of G. maculatus in some detail including; environmental variables, life cycle, larval development, diet and parasitism by platyhelminth and nematode worms. Comparisons were made with other studies in south-east Australia, including Tasmania, and New Zealand. The present study confirmed that, at least throughout most of its range in Western Australia, G. maculatus has established a self-sustaining land-locked reproductive strategy. It is hypothesised that the development of land-locked breeding is an adaptive response to changing coastal geomorphology in the Holocene period that restricted ocean access of rivers and their fauna and caused estuaries to become non-tidal. The principal conclusion arising is that the local biology differs largely in degree rather than kind from elsewhere it has been studied; differences in degree are interpreted as local adaptations to an environment that is both variable and unpredictable Field measurement of environmental variables revealed G. maculatus will withstand salinities to approximately 46 ppt and surface water temperatures to 280 c. Very low dissolved oxygen concentrations to <1.0 mg r1 are accommodated by practicing secondary aerial respiration at the water surface. Galaxias maculatus on the south coast of Western Australia were smaller than those reported from populations elsewhere. Overall tota11engths of Western Australian males and females ranged 23-132 mm compared to 38-187 mm length to caudal fork for south-west Victoria, 31-185 mm standard length for Tasmania and 40-152 mm length to caudal fork for New Zealand fish. In the present study, size varied between the lake and one river population that was smaller. It is hypothesised that reduction in size of Western Australian G. maculatus generally is an adaptive response to avoid predation by piscivorous birds in shallow, confined river pools and lakes. There was a well defined, albeit extended, breeding season between autumn and spring with peak spawning in winter. The season was longer in the relatively stable lake situation and shorter ~ the very variable river situation partly due to the influence of river flow, which is continuous into the lake and intermittent and variable in the rivers. A flow dependent upstream spawning migration was part of the reproductive strategy but there was also the capacity, in certain circumstances, of spawning on falling water levels in years of nil or little flow. There was an almost complete cessation of reproductive activity during summer. Fecundity ranged from 296-2 874 eggs with a mean of 912 and was positively correlated with total length. The overall total lengths at which 50% of females and males and attain sexual maturity were estimated at 52 and 49 mm total length, respectively. For 95% of females and males the total lengths were estimated at 74 and 62mm total length, respectively. Ageing by counting annual growth rings was successful for lake inhabiting fish only, the lack of consistency in growth rings in the river environments was attributed to the extreme variability of these environments. The von Bertalanffy growth equation predicted that, on average, at the end of their first, second and third years females were 61, 81 and 88 mm total length respectively. Male predictions were 56, 74 and 80 mm, respectively. Approximately 75% of males and 62% of females attained sexual maturity at the end of their first year. Excluding larval fish, 73.1, 22.7, 4.1 and 0.1 % were 0+, 1+, 2+ and 3+ fish, respectively. The overall sex ratio females:males was 1.09:1.0, the ratio favoured males for very small fish but favoured females as fish aged and grew. Larval development was described in detail for the first time for Australian G. maculatus. The sequence of fin development was the same as that reported for galaxiids elsewhere, i.e. caudal, dorsal, anal, pectoral and pelvic. Adult fin ray counts were; cauda1 16, dorsa1 9, anal 13, pectoral 12 and pelvic 6-7. Myomeres ranged from 45-50. Development of pigmentation and dentition were described; caniniform teeth began to develop during the late postflexion larval stage. Dietary analysis confirmed a previous description of G. maculatus as an euryphagic carnivore. A wide range of invertebrate food groups including copepods, amphipods and ostracods, aquatic insects as well as terrestrial invertebrates (spiders, winged ants and orthopterans) were consumed. Most variation in diet was explained by site, i.e whether fish were from river or lake environments or which river environment. A lack of replicate samples precluded a rigorous statistical analysis of the influence of either fish size or season on diet. However, a provisional analysis suggested these variables have minimal influence. Larval diets comprised copepods, cladocerans and unicellular algae; with the attainment of postflexion larval stage and development of caniniform dentition, a wider range of dietary items were ingested. One cestode, one trematode and two nematode larval worms infected river and lake inhabiting fish. The cestode, Ligula intestinalis, infected 13% of lake inhabiting fish causing gross disfiguration and probably reduced reproductive success, particularly of males. The degree and severity of cestode infection was much less in rivers, perhaps due to their saline waters. The worms' adult hosts in all cases were piscivorous waterfowl particularly the white-faced heron. At present G. maculatus is widespread and abundant throughout its range in Western Australia. As most of its range is in rivers and lakes which are, and will in the future be influenced by clearing for agriculture, it is likely that increased river recharge due to clearing will initially benefit G. maculatus. However long term change, particularly changes to riparian vegetation structure and species composition, are likely eventually to be inimical as the shading value of vegetation and its habitat value for terrestrial invertebrate food are diminished.

Before the end of 1850, Scottish settlers in Western Australia represented a small minority group of what was, in terms of the European population, a predominantly English colony. By comparison to the eastern Australian colonies, Western Australia attracted the least number of Scottish migrants. This thesis aims to broaden the historiography of Scottish settlement in Australia in the nineteenth century by providing insights into the lives of Westralian Scots. While this thesis broadly documents Scottish settlement, its main focus is Scottish identity. Utilising techniques of nominal record linkage and close socio-biographical scrutiny, this study looks beyond institutional manifestations of Scottish identity to consider the ways in which Scottishness was maintained in everyday lives through work, social and religious practices. This thesis also demonstrates the multi-layered expressions of national identity by recognising Scottish identity in the Australian colonies as both Scottish and British. The duality of a Scottish and British identity made Scots more willing to identify eventually as Westralian Scots.

The hypothesis central to this study is that distinctly Aboriginal patterns of relationship between humans and dogs are still evident in contemporary Aboriginal groups. The relationship's sociological characteristics in traditional and contemporary settings and its implications for canine and human health are also investigated. Field research employing survey, quantitative observation and specimen analysis techniques was conducted in 9 Western Australian Aboriginal groups of various backgrounds and settings. Results were compared to historic-traditional accounts and dog ownership studies in non-Aboriginal groups. Traditionally dogs served Aboriginals most importantly for supernatural protection and to assist the collection of small game by women. In non-isolated groups, traditional utilitarian motives were superseded by the Western concept of dogs as companions. Demographically, the Aboriginal dog populations surveyed were relatively large, and most dogs were classified as medium sized non-descript cross-breds. Dogs were more commonly owned by adult and aged individuals, rather than by family units as is the Western cultural norm. Most dogs remained with their original owner and retained their original name for life. Traditional values of respect towards dogs were compromised to the discriminatory care of higher status animals only, effecting selection pressure against undesirable dogs, particularly females. Similarly, while many aged people were opposed to culling, most respondents regarded community pup production as excessive and accepted culling as necessary. Nevertheless prevention was the preferred option, with strong support for the previously unfamiliar concept of ovariohysterectomy. Pups were raised in some respects like children in the traditional manner, indulgence giving way in adulthood to expectations of self-reliance rather than obedience. Most dogs were in good physical and psychological condition, though more likely to be afflicted by sarcoptic mange than other Australian dogs. Other parasites occurred at or below expected frequencies. Close physical contact with dogs coupled with favourable microclimates allowed ample opportunity for transmission of canine zoonoses, but the actual risk to human health remains poorly documented.

The aim of this study was to determine the size and age compositions, growth rates, reproductive biology, dietary compositions and mesh selectivity of the King George whiting Sillaginodes punctata, the Australian herring Arripis georgiana, the yelloweye mullet Aldrichetta forsteri and the sea mullet Mugil cephalus in Wilson Inlet. These biological variables were chosen for analysis since the resultant data would be of use for managing these commercially important marine species in this seasonally closed estuary, which is located on the southern coast of Western Australia. Samples of each of the above species were typically collected, in at least every other month between April 1988 and April 1990, by using seine netting and gill netting at several sites, distributed at regular intervals throughout the 48 km2 basin of Wilson Inlet, and by gill netting at one site in each of two tributary rivers. The ages of Sillaginodes punctata, Aldrichetta forsteri and Mugil cephalus were determined using the annuli on scales, whereas those of Arripis georgiana were determined using the annuli on otoliths. The annuli on the above hard structures of the four species were shown to be formed annually before they were used for aging purposes. Although at least four year classes of each species were found in Wilson Inlet, the 0+ year class of none of the species was well represented in this estuary. The paucity of this age class was probably attributable, in most cases, to the spawning grounds of these species being located some distance away on the lower west coast of Australia. However, the absence of any 0+ S. punctata in one year was attributed to the mouth of Wilson Inlet being closed at a crucial time, which thereby prevented the recruitment of this species into this estuary. Virtually all of the S. punctata caught in Wilson Inlet were less than the LSo at first maturity, which implies that none of this species return to this estuary after they have emigrated to sea, matured and spawned. However, appreciable numbers of each of the other three species were found at lengths greater than their respective Lsos. There was clear evidence that large A. forsteri tended to leave the estuary soon after the bar at the estuary mouth was breached. In contrast, length-frequency distributions indicated that large A. georgiana often tended to remain in the estuary, even when they exceeded the LSo at first maturity and the estuary mouth was open. The maximum lengths attained by S. punctata, A. georgiana, A. forsteri and M. cephalus were 491,373,430 and 525 mm, respectively, while the maximum ages attained by these four species were 5+, 7+, 5+ and 4+, respectively. While there was no significant difference between the growth rates of the two sexes of either S. punctata or M. cephalus, the overall growth rates of the females of A. georgiana and A. forsteri were both greater than those of their males. Each fish was assigned a maturity stage using the criteria of Laevastu (1965). The maximum maturity stage recorded for the gonads of S. punctata was IV (maturing). The fact that no S. punctata with spawning (stage VI), spent (stage VII), recovering spent (stage VIII) or resorbing gonads were found provides overwhelming evidence that this whiting species neither spawns in Wilson Inlet nor returns to this estuary after it has spawned at sea. Furthermore, spawning and recently-spent gonads were never found in individuals of either A. georgiana, A. forsteri or M. cephalus, whch implies that these species also do not spawn in the estuary. However, some A. georgiana and A. forsteri with recovering spent gonads were found in Wilson Inlet, which indicates that some individuals of these two species enter the estuary after spawning at sea. There was no indication that this also applied with M. cephalus. Yet, the gonads of some individuals of this latter species and also of A. georgiana contained resorbing gonads, i. e gonads that had reached a reasonably advanced stage, but not maturity, and which were now undergoing regression. The fish with these gonads had presumably been trapped in the estuary at the time their gonads were developing and could not therefore emigrate out to their marine spawning areas. The dietary compositions of the four species were shown to be significantly different. Sillaginodes punctata and A. georgiana fed mainly on benthic macroinvertebrates, while all but the smallest M. cephalus were detritivores and A. forsteri was an omnivore. Furthermore, S. punctata fed mainly on errant polychaetes and nemerteans, whereas A. georgiana ingested decapods, mysids and other teleosts. The diets of each species underwent size-related changes. The differences in dietary compositions among and within species would reduce the likelihood of inter- and intraspecific competition for food resources. Comparisons have been made between traditional methods for estimating the selectivity of S. punctata, A. georgiana, A. forsteri and M. cephalus in gill nets and a new method of analysis developed (with Dr. N. Hall), which incorporates the best features of the traditional methods.

This thesis examines a broad spectrum of physiological and silvicultural features of the highly valued woody angiosperm hemi-parasite Santalurn album L. (Indian sandalwood) in relation to its culture in plantations in northern Western Australia. Topics covered include allometry of host and Santalum when grown as single plant pairings in both field and pot culture, nutritional interactions between Santalum and beneficial and non-beneficial hosts, deleterious influences of parasitism on plantation productivity and heartwood induction in young trees. In Western Australia sandalwood is grown in the nursery for 8 months before establishment in the field and during this time a pot host is introduced. Survival of Santalurn after field establishment and its subsequent growth were significantly affected by the time of introduction of the pot host, Alternanthera nana. Increasing the period of the Santalum : Alternanthera association in the nursery to 109 days prior to field establishment markedly increased early growth of Salztalum plantations. Introduction at 134 days prior to field establishment was detrimental to the parasite as the Alternanthera was too vigorous for the small Santalum seedlings. Santalurn plants had a lower root : shoot ratio lower when cultured with Alternanthera in the nursery prior to field establishment compared with seedlings grown without Alternanthera. Alterrzantlzera survival in the field was high when it had been grown with Santalum for 12 weeks or more in the nursery prior to field establishment. After 1 1 weeks in the field a strong negative linear relationship was shown between Santalunz root : shoot ratio and Alternarzthera dry weight, and a positive linear relationship between Salztalum DW and Alternanthera DW. In Western Australia Santalu~n is established in the field with an intermediate host which nourishes the parasite for 3-5 years before Santalum becomes dependent on its long-term host and the intermediate host dies. The relationship between Santalum and several species tested as intermediate hosts was examined by pairing Santalum seedlings with intermediate host seedlings in 25 litre pots over a 10 month period. Growth of Santalum in pot culture with three N2-fixing woody intermediate hosts (Sesbania forrnosa, Acacia traclzycarpa and A. ampliceps), the woody non N2-fixing Eucalyptus camaldulensis or without a host varied considerably between host treatments. Santalum growth was greater and root : shoot ratio lower for seedlings grown with N2-fixing hosts compared with seedlings grown with E. carnaldulensis or with no host. The root : shoot ratio of unattached Santalum increased exponentially over time, whereas for all other treatments it remained relatively constant. An assessment of the value of the hosts, termed host use efficiency, was computed as Santalum shoot DW / host shoot DW. The host use efficiency of A. trachycalpa was greater than that of the other hosts. The xylem sap of hosts and Sarztalum, and ethanolic extracts of endophytic tissue of haustoria of Santalzkm were analysed for amino acids, organic acids and sugars to determine which solutes were available in the host and which were extracted by the Santalum haustoria from different hosts. There were similarities between Santalum and legume hosts in concentration and composition of xylem sap amino acids, and in the amino acid spectra of the corresponding Santalum endophytic tissue, whereas there were low N levels in xylem sap of E. camaldulensis and dissimilarities between its amino acid composition and that of Santalum. This indicated substantial direct intake of xylem N by Santalum from legume hosts but little N from the xylem sap of E. canzaldulensis. There were high concentrations of asparagine, glutamate, aspartate and y-amino glutamate in the xylem sap of the legume hosts, while in the non-legume the most common amino acids were glutamate, aspartate, glutamine and arginine. Proline, the predominant amino acid in the xylem sap of Santalum acurninatum growing in natural vegetation (Tennakoon et al. 1997) was not detected or present in very low concentrations in Santalurn album under these conditions. in the non-legume. Xylem sap of hosts contained variable amounts of sugars (sucrose, glucose and fructose) and organic acids (fumaric, citric and malic acid), whereas that of the parasitic Santalum was dominated by fructose and malic acid. Dissimilarities in the proportional amounts of xylem-borne sugars and organic acids were particularly evident for the E. camaldulensis : Santalum partnership. Diurnal profiles of photosynthesis and transpiration of Santalum were closely similar to those for corresponding hosts, whereas the midday leaf water potential of Santalum was consistently more negative than that of corresponding hosts. Net photosynthesis and water use efficiency was lower, but transpiration rates were similar to that of corresponding hosts. Nitrogen concentrations of foliage of Santalum were higher than their hosts, and higher when on legume hosts than on E. camaldulensis, or without a host. Nitrogen concentrations of Santalum foliage was strongly correlated with net photosynthesis and water use efficiency of Santalum. 813C values of shoot dry matter of Santalum were poorly correlated with instantaneous water use efficiency of Santalum. Tissue water relations of Santalum were similar to that of water-stress tolerant species. S. formosa proved the best host followed by Acacia ampliceps and A. traclzycarpa based on dry matter gains of Santalum. Estimates of heterotrophic gain of C of Santalum when grown in association with the legume hosts over a nine week period indicate 57.9% of C was derived from A. ampliceps, 45.5% from A. trachycarpa and 34.6% fiom S. fomosa. Abundance of haustorial attachments on roots of hosts was poorly correlated to Santalum shoot DW. Root nodules of legume hosts were parasitised by a small proportion of Santalum haustoria. Sodium and phosphorus concentrations of foliage of Santalum were generally higher than that of corresponding hosts. Net gains of calcium, potassium, phosphorus and sodium in Santalum was greatest when grown in association with hosts richest in the corresponding element. Net losses or only small gains of calcium, potassium, phosphorus and sodium were recorded when Santalum was grown with E. camaldulensis or without a host suggesting that Santalum has limited ability for uptake of those minerals through its own root system. To understand the effect of hosts on the productivity of a Santalum plantation a young plantation of Santalum with three host species Cathormion umbellatum, Sesbania formosa and Acacia anuera was selected to study the relationship between host quality and distance of hosts from Santalunz on Santalum health. The selected plantation showed marked decline in health and vigour of both Santalum and hosts between years 3 and 5. Parameters of the host plants were assessed to select the best predictor of Santalunz crown health. The height and diameter growth increment of Santalum between years 3 and 5 was strongly correlated to Santalum crown health. Santaluin crown health and growth increased as host quality increased, and the distance of host fiom Santalum decreased. An index, which combined host quality and the distance of the host from that of Santalum, was a better predictor of Santalum crown health than host distance or quality alone. The age at which heartwood is initiated in Santalum album under plantation conditions in Western Australia in unknown, but in natural stands in India it occurs between 10-13 years of age (Rai 1990). A field experiment was conducted to determine the efficacy of stem injections of paraquat andlor ethrel in initiating heartwood formation in five year old Santalum trees in a plantation. Trees injected with paraquat alone had a significantly greater extension of induced heartwood, both radially and vertically, than those trees injected with ethrel alone or distilled water. Eight months after treatment with paraquat or ethrel or a combination of these chemicals induced heartwood was formed, which had high lipid, and low starch and polysaccharide concentrations compared to the sapwood. Induced heartwood from both chemical treatments and their combinations contained total volatile oil and santalol oil (alpha and beta santalol) concentrations that were equal to or greater than that of naturally formed heartwood and greater than that of sapwood. Moisture content, and concentrations of K and Mg, and in some treatments Ca of induced heartwood were significantly lower than that of sapwood. The thesis concludes with a synthesis of the findings and suggestions for future research, with special reference to mid-rotation aspects of Santaltrm plantation silviculture.

This case study, conducted in a vocational and technical education institution at post secondary level, was concerned with the effects of an organization development intervention on the ability of an organization to implement a planned change initiated by itself. More specifically, the study hypothesized that organization development, or change to the organization itself, could enhance the process of planned change by the organization. The study develops at length the concept and theory of implementing planned change, of the critical importance of common understandings and shared expectations to this process, and of the centrality of resocialization and social interaction in successful implementation. The study also lists in detail the events and procedures used in this particular organization development intervention, as well as the concept and theory underlying organization development. A number of principles which guided the author's intervention activities are also listed and examined. Data on organizational change induced by the intervention were collected over a period of two years through a questionnaire, used for repeated measures, and through participant observation. These data are presented both quantitatively and qualitatively in the study. The qualitative data are presented in the form Eisner (1979) has described as "educational criticism". Data on the implementation of planned change were collected through a questionnaire, used for repeated measures, a structured interview technique closely based on the Levels of Use methodology (Ha22 et aZ, 1975), and through participant observation data. Data were again collected over a period of two years and are presented both quantitatively and qualitatively. The study indicates clearly that the organizational intervention was successful in bringing about organizational change across a broad range of variables. These changes included organizational elements which research has identified as determinants of the implementation process, The study also indicates that during the period of the intervention the education institution concerned enhanced its ability to implement planned change, and that this enhanced ability was closely related to the organizational changes which had occurred as a result of the organization development intervention.

The major question addressed by this project was to determine if the long-necked, freshwater turtle Chelodina oblonga, vocalise underwater and whether their vocal activity could be related to behavioural or ecological aspects of their lives. These turtles often live in wetlands where visibility is restricted due to habitat complexity or light limitation caused by factors such as tannin-staining, or turbidity. For many aquatic animals, sound is a useful means of communication over distances beyond their visual acuity. This thesis gives the first detailed account of the underwater vocal repertoire of C. oblonga. In total, over 230 days were spent in the field and more than 500 hours of tape recordings were made for this research. Initially, a number of recordings took place in three wetlands known to support turtle populations: Blue Gum Lake; Glen Brook Dam; and Lake Leschenaultia in Perth, Western Australia; in order to determine the nature of the freshwater sound field and place turtle vocalisations into the context in which they were vocalising. The wetlands differed in terms of degree of enrichment, substrate material, water depth and habitat complexity. Recordings were made over a four-week period in the last month of summer and the first week of autumn (Feb-Mar 2003). Invertebrate sweeps were also taken over a two-week period at each recording site to determine if invertebrate distributions were related to patterns of sonic activity. To determine the influence of wind on ambient noise; recordings were undertaken on winter mornings (June-August, 2003) at Blue Gum Lake and Glen Brook Dam at locations north, south, west and east for four different wind speeds – Beaufort Wind Scale (BWS) 0,1,2 & 3. There were seven distinctive calls recognised in the recordings. The frequency bandwidth most utilised by organisms was between 3 kHz up to around 14 kHz, with the exception of the ‘bird-like song’; which extended from 500 Hz up to around 10 kHz. Blue Gum Lake contained a more diverse and abundant assemblage of invertebrates than Lake Leschenaultia and Glen Brook Dam. Correspondingly, a greater diversity of calls was recorded at Blue Gum Lake, as well as the presence of chorus activity, which was not heard at the two less-enriched sites. The periods of greatest diversity and abundance of macroinvertebrates was synonymous with the increased sonic activity at dusk and midnight with noise levels greatest at dusk in particular, and to a lesser extent at midnight. There was no difference in ambient noise at Blue Gum Lake or Glen Brook Dam at wind speeds of Beaufort Wind Scale 0, 1 and 2. Turtles from three populations were recorded in artificial environments: consisting of round, plastic, above-ground ponds (1.8m dia. x 0.65m depth), which were set up to recreate small wetlands. Recordings occurred from September to October, 2003 and from February to December, 2004 as well as January, 2005. Seven hatchling and five juvenile turtles (CL <10cm) were also recorded in order to ascertain whether very young turtles vocalised. Hatchlings were recorded in a glass aquarium (35.5cm length x 20cm width x 22.0cm depth) and juveniles were placed into a below-ground outdoor pond (1m length x 0.5m width x 0.4m depth). Recordings occurred from as early as 4.30am (dawn recordings) to as late as 1.30am (evening recordings). The recordings revealed that turtles utilise an underwater acoustic communication system (calling at the water’s surface was also noted but these were not recorded or a part of this research) involving a repertoire of both complex and percussive sounds with short, medium and potentially long-range propagation characteristics. Complex structures included harmonically related elements (richly or sparsely) and different rates of frequency modulation. Frequency use extended beyond the in-air auditory sensitivity known for a single species of turtle studied from the family Chelidae; with calls ranging from around 100 Hz in some of the percussive displays, to as high as 3.5 kHz in some complex calls, with ‘clicks’ extending beyond the 20 kHz upper limit of the recording system. However, most of C. oblonga’s vocalisations had dominant frequencies below 1 kHz. Turtles were intermittent callers with an extensive vocal repertoire of seventeen (17) vocal categories - highly suggestive of complex social organisation. Vocalisations included: a) clacks; b) clicks; c) squawks; d) hoots; e) short chirps; f) high short chirps; g) medium chirps; h) long chirps; i) high calls; j) cries or wails; k) cat whines; l) grunts; m) growls; n) blow bursts; o) staccatos; p) a wild howl; and q) drum rolling. Also, two sustained ‘pulse-bouts’ were recorded during the breeding months, hypothesised to function as acoustic advertisement displays – possibly ‘calling songs’. Hatchling turtles were not heard to vocalise within the audible range. Only a single complex vocalisation was heard produced by the juvenile turtles, with a number of percussive calls. Preliminary playback trials were conducted under free-field conditions and within an artificial environment, which consisted of a below ground rectangular tank (2.4m length x 0.8m width x 0.6m deep). A number of turtle calls recorded in the artificial ponds were selected for playback. A UW 30 speaker was used for broadcast of calls. The free-field playbacks occurred at Mabel Talbot Lake and Blue Gum Lake during the months of April and May, 2005. Playback using 14 seconds of an artificially constructed sequence from the sustained ‘pulse-bout’ occurred in the artificial channels. This sequence consisted of some of the first phase pulses followed by a section of the ‘vibrato’. The preliminary free-field playback trials indicated that turtles had some interest in the calls being played by responding with an ‘alert posture’. Turtles were shown to remain in the alert posture for a significantly longer time than when no sound was played or when white noise was played. The extensive repertoire and initial responses to the free-field playbacks indicated that sound has some biological importance for C. oblonga, although results of playbacks under artificial conditions were inconclusive.