South Of Tasmania Research Articles

Movement of hydrological fronts and widespread erosional events in the southwestern Tasman sea during the Late Quaternary*

The planktonic foraminiferal palaeotemperatures and oxygen isotopes, radiocarbon dates and calcareous nanno‐plankton biostratigraphy of six deep‐sea cores in the southwestern Tasman Sea are presented, along with the nannoplankton biostratigraphy of the tops of 23 other cores in the region. A complex history of deposition and erosion is indicated, with development of hiatuses at 10 ka, and widespread absence of sediments younger than 73 ka. The history of movement of the major hydrological fronts over the areas west to southwest of Tasmania has been deduced from palaeotemperature records of the undisturbed core segments. During the Last Glacial Maximum, the Subtropical Convergence was positioned north of 42°S, 145°E. During the subsequent deglaciation and Holocene the front rapidly moved southward, with its southern limits established south of 47°S. Presently the northern limit of the Polar Front south of Tasmania is positioned south of ∼50cS, and palaeotemperatures and the absence of silica‐rich sediments in all cores north of there, suggests that the front has been south of there during the past 500 000 years.

Distribution of calcareous nannoplankton near the Subtropical Convergence, south of Tasmania, Australia

The floral composition of living calcareous nannoplankton collected from surface waters near the Subtropical Convergence (STC), offshore south-eastern Tasmania, in January 1994 is presented. Emiliania huxleyi represented more than 90% of all coccolithophorids. Scanning electron microscopy showed a substantial increase in intraspecific variation of E. huxleyi, and in variation in coccolith size of Calcidiscus leptoporus, E. huxleyi type A and C. leptoporus (small), north of the STC. It is postulated that the percentage abundance of these taxa may be used to determine the position andlor shift of the STC zone through time, and therefore may be of use for palaeoceanographic studies.

Alpine lichens of tasmania's south west wilderness

The climate, geology and vegetation of Tasmania's South West wilderness are described briefly, with particular reference to lichens. One hundred and sixty-two lichens are recorded from alpine altitudes in the region and the major habitats for alpine lichens are discussed. The flora differs significantly from that of other Tasmanian mountain systems, and this is attributed in part to geology and macroclimate. The region is rich in Tasmanian endemics and distinctly austral species with restricted geographical distributions.

Implications from Mitochondrial DNA for Management to Conserve the Eastern Barred Bandicoot (Perameles gunnii)

On mainland Australia, the eastern barred bandicoot, Perameles gunnii, is confined to a relic wild population numbering less than 100 individuals in the city of Hamilton. Animals derived from this population are being bred in captivity in order to promote their recovery. The species also exists in Tasmania, where tittle is known of its conservation and taxonomic status. Mitochondrial DNA variability was compared within and between populations of P. gunnii using restriction fragment length polymorphisms. Genetic variability was found to be high among P. gunnii in Hamilton compared to those in Tasmania (higher diversity index, nucleotide sequence divergence, and greater number of haplotypes), despite the known decline and subdivision of the Hamilton population. Restriction fragment length polymorphisms distinguished animals from the east and the west of Hamilton and from the north and south of Tasmania. Nucleotide sequence divergence was substantial (2.2–2.5%) between Hamilton and Tasmania. Implications are that captive breeding and reintroduction should be designed to genetically represent the structure within Hamilton in order to minimize inbreeding and that the introduction of Tasmanian P. gunnii would not benefit the Hamilton population. It is concluded that mitochondrial DNA markers clearly can provide useful information about the history and current status of endangered marsupial populations, to the benefit of conservation management.

Alpine lichens of Tasmania's South West wilderness

The climate, geology and vegetation of Tasmania's South West wilderness are described briefly, with particular reference to lichens. One hundred and sixty-two lichens are recorded from alpine altitudes in the region and the major habitats for alpine lichens are discussed. The flora differs significantly from that of other Tasmanian mountain systems, and this is attributed in part to geology and macroclimate. The region is rich in Tasmanian endemics and distinctly austral species with restricted geographical distributions.

Organic carbon transport from the Southern Ocean and bacterial growth in the Antarctic intermediate Water masses of the Tasman Sea

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 119:291-297 (1995) - doi:10.3354/meps119291 Organic carbon transport from the Southern Ocean and bacterial growth in the Antarctic intermediate Water masses of the Tasman Sea Moriarty, D. J. W., O'Donohue, M. J. The concept that organic carbon is transported to the equatorial region at intermediate water depths from subantarctic frontal zones has been re-investigated using the tritiated thymidine method to determine rates of bacterial DNA synthesis in water masses of the Tasman Sea. There was a higher bacterial growth rate and thus a higher flux of organic carbon through bacteria in the Antarctic Intermediate Water (900 to 1000 m depth) than in the water masses immediately above or below in the Tasman Sea east and south of Tasmania. Values for bacterial production were 4 to 8 ug C m-3 d-1, which are equivalent to a consumption of about 3 to 6 ul O2 l-1 yr-1. In the deeper layer at 1200 to 1500 m, rates were 3 to 4 times lower. These rates are compatible with other data on oxygen utilisation. Our results support the concept that organic matter sinks with downwelling water in the zone between the Subtropical Convergence and the Polar Front in the Southern Ocean and is advected towards the equator below the photic zone. Oceanic carbon cycling . Southern Ocean . Pacific Ocean . Bacteria Full text in pdf format PreviousNextExport citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 119. Publication date: March 23, 1995 Print ISSN:0171-8630; Online ISSN:1616-1599 Copyright © 1995 Inter-Research.

MESOZOIC TECTONICS OF THE OTWAY BASIN REGION: THE LEGACY OF GONDWANA AND THE ACTVE PACIFIC MARGIN—A REVIEW AND ONGOING RESEARCH

Mesozoic extension along Australia's southern margin and the evolution and architecture of the Otway Basin were probably controlled by three factors: 1) changes in global plate movements driven by mantle processes; 2) the structural grain of Palaeozoic basement; and, 3) changes in subduction along Gondwana's Pacific margin. Major plate realignments controlled the Jurassic onset of rifting, the mid-Cretaceous break-up and the Eocene onset of rapid spreading in the Southern Ocean.The initial southern margin rift site was influenced by the northern limit of Pacific margin (extensional) Jurassic dolerites and the rifting may have terminated dolerite emplacement. Changed conditions of Pacific margin subduction (e.g. ridge subduction) in the Aptian may have placed the Australia-Antarctic plates into minor compression, abating Neocomian southern margin rifting. It also produced vast amounts of volcanolithic sediment from the Pacific margin arc that was funnelled down the rift graben, causing additional regional subsidence due to loading. Albian orogenic collapse of the Pacific margin, related to collision with the Phoenix Plate, influenced mid-Cretaceous breakup propagating south of Tasmania and into the Tasman Sea.Major offsets of the spreading axis during breakup, at the Tasman and Spencer Fracture zones, were most likely controlled by the location of Palaeozoic terrane boundaries. The Tasman Fracture System was reactivated during break-up, with considerable uplift and denudation of the Bass failed rift to the east, which controlled Otway Basin facies distribution. Palaeozoic structures also had a significant effect in determining the half graben orientations within a general N-S extensional regime during early Cretaceous rifting. The late Cretaceous second stage of rifting, seaward of the Tartwaup, Timboon and Sorell fault zones, left a stable failed rift margin to the north, but the attenuated lithosphere of the Otway-Sorell microplate to the south records repeated extension that led to continental separation and may be part of an Antarctic upper plate.

Keeping in Touch: Vegetation Prehistory on Both Sides of the Tasman

At the end of the Cretaceous New Zealand broke away from the Australian-Antarctic continental mass and was physically isolated by the Tasman Sea. Early in the Tertiary New Zealand moved a long way north relative to Australia, but with the rapid northward movement of Australia, starting in the Eocene, Australia overtook New Zealand, so that much of the South Island of New Zealand now lies south of Tasmania. The northward and relative movements of the two blocks provide an interesting framework for comparing the development of their vegetation. In the Late Cretaceous, New Zealand and Australia were physically attached and shared a flora dominated by podocarp and araucarian conifers and deciduous angiosperms, consistent with growth in a polar latitude with periods of winter darkness. When New Zealand broke away and moved north, a typically evergreen angiosperm-dominated flora developed. This showed similarities to the extant and fossil flora of the Australian mainland. To the south, Tasmania developed a quite distinct flora often dominated by conifers. In the Early-mid Miocene, when New Zealand lay at the same latitude as south eastern Australia, a change from Nothofagus dominated rainforest to, at times, drier vegetation including wet sclerophyll with Eucalyptus, occurred in both regions. This may record the roughly synchronous effects of more northerly tracking Sub Tropical High Pressure systems. In the Late Miocene-Pliocene there was a return to Nothofagus-podocarp dominance in both Australia and New Zealand. Today, the conifer-dominated communities of Tasmania have largely retreated to montane regions where they form dwarf shrublands, and have disappeared from the Australian mainland. In New Zealand the situation has quite reversed from that of much of the Tertiary, and conifers now form a prominent part of many rainforest communities. The evidence suggests Australia and New Zealand can be thought of as a single biogeographic entity, with the vegetation in both landmasses responding principally to climate change, with relatively free exchange, at least in one direction, of plants, rather than evolving in isolation since Late Cretaceous oceanic rifting.

Response to sowing time of three contrasting Australian cultivars of oilseed rape (Brassica napus)

SUMMARYSerial sowings of three cultivars of oilseed rape were made from autumn (May) to spring (October) at two sites, one in the north and one in the south of Tasmania, in 1981. The highest seed yields at both sites exceeded 5 t/ha from early sowing, ranging down to c. 2 t/ha from late sowing at a site where irrigation was adequate and to < 1 t/ha where late-sown crops suffered from water stress. The midseason cultivar Marnoo gave the highest yields at both sites, resulting from a combination of substantial (800 g/m2) top growth before flowering, excellent seed survival, a long period for grain filling and high oil content. The early-flowering line RU1 made much less growth before flowering; while this was partly made up for in later growth, nearly as many seeds per pod being retained as in Marnoo, oil content was low. The later-flowering cultivar Wesbell made more growth before flowering than the other cultivars, but when sown early it tended to grow tall, lodge and lose many pods in the dense, tangled canopy. This, combined with generally fewer seeds per pod, resulted in a much less efficient crop in allocation of dry matter to seeds and oil. Wesbell failed to flower uniformly from the late sowings, indicating segregation for vernalization response. The many immature seeds at harvest gave a low overall oil content. All three cultivars responded to vernalization and longer photoperiod in a pot experiment. While photoperiod appeared to be the main factor controlling the development rate to flowering in the field, there were interactions with vernalization response andtemperature.

Geriatric assessment—An Australian idea

Residential care provision for elderly people varies from country to country as well as from state to state within Australia, yet despite this a universal feature of all countries is community pressure for increased provision of both nursing home and hostel accomodation. Australia has developed the concept of multidisciplinary assessment of elderly people requesting residential care. This paper describes the effectiveness of one assessment team in the south of Tasmania in reducing demand for residential accomodation and in improving outcomes for the clients referred to the team.

New records ofSomniosus(Elasmobranchii: Squalidae) from Australasia, with comments on the taxonomy of the genus

Abstract Records of Somniosus from the Southern Hemisphere are few and are poorly documented. Four new specimens are recorded: Somniosus rostratus from New Zealand and S. pacificus from south of Tasmania, and New Zealand. Comparative material was examined and the specimens were identified on the basis of morphometrics, tooth shape and number, and dermal denticles. Photographs of two further specimens from New Zealand were also examined, but the species were not determined. Southern hemisphere Somniosus are represented by S. pacificus and S. rostratus. A revised key to the genus is presented.

Discovery by the Australasian Antarctic Expedition of Important Submarine Banks

DISCOVERY BY THE AUSTRALASIAN ANTARCTIC EXPE? DITION OF IMPORTANT SUBMARINE BANKS. By Prof. T. W. EDGEWORTH DAVID, F.K.S. Captain J. K. Davis, of Dr. Mawson's Australasian Antarctic ship Aurora, has recently reported the discovery, as the result of an oceanographic cruise, of an important rocky ridge or bank about 200 miles south of Tasmania. The Aurora left Hobart on this cruise on November 12, 1912, returning to Hobart on December 14 following.