Cooperative Research Centre

About: Cooperative Research Centre is a based out in . It is known for research contribution in the topics: Population & Sea ice. The organization has 7633 authors who have published 8607 publications receiving 429721 citations.

Formation and export of dense shelf water from the Adélie Depression, East Antarctica

Abstract: [1] Coastal polynyas in the Adelie Depression are an important source of Antarctic Bottom Water to the Australian-Antarctic Basin. We present time series (April 1998 to May 1999 and August 1999 to February 2000) of data from temperature-salinity sensors, in both the Adelie Depression and the known outflow region of the Adelie Sill, to describe the annual cycle of shelf water densities. From April through September, salinification beneath the polynya produces dense shelf waters. During September–October, shelf water densities in the depression peak at 27.94 kg m−3, and the cooling and freshening signature of Ice Shelf Water is observed north of Buchanan Bay. In November–December, shelf water densities decrease as intrusions of warm and relatively fresh modified Circumpolar Deep Water enter east of the Adelie Sill. From January–March the surface layer is conditioned by the cooling of the atmosphere, which overturns the upper water column. At the Adelie Sill, observed daily mean currents were approximately 10 cm s−1 with intense instantaneous currents greater than 50 cm s−1 at the sill depth. Using an idealized outflow region with a rectangular cross-sectional area (6 × 106 m2), we present the first estimates of shelf water export by potential density class. Assuming shelf water with a minimum density of 27.88 kg m−3 has sufficient negative buoyancy for downslope mixing and a fourfold volume increase (1:3 mixing ratio) from entrainment, the dense shelf water export of 0.1–0.5 Sv results in an annual average production of bottom water in this region of between 0.4 and 2.0 Sv. The wide range in bottom water estimate results from data limitations, and a narrowing of this range requires further mooring observations.

Microplastics generated when opening plastic packaging.

Abstract: Millions of tonnes of plastics have been released into the environment. Although the risk of plastics to humans is not yet resolved, microplastics, in the range of 1 μm - 5 mm, have entered our bodies, originating either from ingestion via the food chain or from inhalation of air. Generally there are two sources of microplastics, either directly from industry, such as cosmetic exfoliants, or indirectly from physical, chemical and biological fragmentation of large (>5 mm) plastic residues. We have found that microplastics can be generated by simple tasks in our daily lives such as by scissoring with scissors, tearing with hands, cutting with knives or twisting manually, to open plastics containers/bags/tapes/caps. These processes can generate about 0.46–250 microplastic/cm. This amount is dependent on the conditions such as stiffness, thickness, anisotropy, the density of plastic materials and the size of microplastics.This finding sends an important warning, that we must be careful when opening plastic packaging, if we are concerned about microplastics and care about reducing microplastics contamination.

Using species distribution models to infer potential climate change-induced range shifts of freshwater fish in south-eastern Australia

Abstract: There are few quantitative predictions for the impacts of climate change on freshwater fish in Australia. We developed species distribution models (SDMs) linking historical fish distributions for 43 species from Victorian streams to a suite of hydro-climatic and catchment predictors, and applied these models to explore predicted range shifts under future climate-change scenarios. Here, we present summary results for the 43 species, together with a more detailed analysis for a subset of species with distinct distributions in relation to temperature and hydrology. Range shifts increased from the lower to upper climate-change scenarios, with most species predicted to undergo some degree of range shift. Changes in total occupancy ranged from –38% to +63% under the lower climate-change scenario to –47% to +182% under the upper climate-change scenario. We do, however, caution that range expansions are more putative than range contractions, because the effects of barriers, limited dispersal and potential life-history factors are likely to exclude some areas from being colonised. As well as potentially informing more mechanistic modelling approaches, quantitative predictions such as these should be seen as representing hypotheses to be tested and discussed, and should be valuable for informing long-term strategies to protect aquatic biota.

An independently dated 2000-yr volcanic record from Law Dome, East Antarctica, including a new perspective on the dating of the 1450s CE eruption of Kuwae, Vanuatu

Abstract: Volcanic eruptions are an important cause of nat- ural climate variability. In order to improve the accuracy of climate models, precise dating and magnitude of the climatic effects of past volcanism are necessary. Here we present a 2000-yr record of Southern Hemisphere volcanism recorded in ice cores from the high accumulation Law Dome site, East Antarctica. The ice cores were analysed for a suite of chemistry signals and are independently dated via annual layer counting, with 11 ambiguous years at 23 BCE, which has presently the lowest error of all published long Antarc- tic ice cores. Independently dated records are important to avoid circular dating where volcanic signatures are assigned a date from some external information rather than using the date it is found in the ice core. Forty-five volcanic events have been identified using the sulphate chemistry of the Law Dome record. The low dating error and comparison with the NGRIP (North Greenland Ice Core Project) volcanic records (on the GICC05 timescale) suggest Law Dome is the most accurately dated Antarctic volcanic dataset, which will im- prove the dating of individual volcanic events and potentially allow better correlation between ice core records, leading to improvements in global volcanic forcing datasets. One of the most important volcanic events of the last two millennia is the large 1450s CE event, usually assigned to the eruption of Kuwae, Vanuatu. In this study, we review the evidence sur- rounding the presently accepted date for this event, and make the case that two separate eruptions have caused confusion in the assignment of this event. Volcanic sulphate deposition es- timates are important for modelling the climatic response to eruptions. The largest volcanic sulphate events in our record are dated at 1458 CE (Kuwae?, Vanuatu), 1257 and 422 CE (unidentified).