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The WOCE Hydrographic Program (WHP) and repeated hydrographic data were used to document overall property changes of the Antarctic Bottom Water (AABW) in the Australian-Antarctic Basin between the 1990s and 2000s. Strong cooling and freshening is observed on isopycnals for layers denser than &ggr;5 = 28.30. Changes in average salinity and potential temperature below this isopycnal correspond to basin-wide warming of 1300±200TW and freshening of 24±3 Gt yr-1. While freshening can be explained by freshening of major source waters, i.e., the High Salinity Shelf Water (HSSW) of the Ross Sea and the dense shelf water formed in the Adélie and George 10 V Land (AGVL) region, extensive warming of the AABW cannot be explained by warming of the source waters. A possible cause of warming of the AABW is a decrease in supply of the Ross Sea Bottom Water (RSBW). Hydrographic profiles between the Drygalski Trough of the Western Ross Sea and 150° E were analyzed in the context of a simple advective-diffusive model to assess the causes of the observed changes. 15 The RSBW has also warmed by a larger amount than its source water (the HSSW). The model suggests that the warming of the RSBW observed between the 1970s and 2000s can be explained by a 21±23% reduction in transport of the RSBW and an enhancement of the vertical diffusion of heat as a result of a 30±7% weakening of the abyssal stratification. Freshening of the HSSW reduced the salinity and density stratifi20 cation between the bottom water layer and overlying ambient water. Hence, freshening of the HSSW both directly freshened and indirectly warmed the RSBW by enhancing the vertical mixing. A simple box model suggest that changes in property and volume transport (decrease of 6.7% is assumed between the year 1995 and 2005) of the RSBW can explain 51±6% of the warming and 84±10% of the freshening observed in 25 the AABW. These facts demonstrate that changes in both property and volume transport of the RSBW have contributed to the warming and freshening of the AABW in the Australian-Antarctic Basin. [ABSTRACT FROM AUTHOR]

Turnip mosaic virus (TuMV) is a potyvirus that is transmitted by aphids and infects a wide range of plant species. We investigated the evolution of this pathogen by collecting 32 isolates of TuMV, mostly from Brassicaceae plants, in Australia and New Zealand. We performed a variety of sequence-based phylogenetic and population genetic analyses of the complete genomic sequences and of three non-recombinogenic regions of those sequences. The substitution rates, divergence times and phylogeographical patterns of the virus populations were estimated. Six inter- and seven intralineage recombination-type patterns were found in the genomes of the Australian and New Zealand isolates, and all were novel. Only one recombination-type pattern has been found in both countries. The Australian and New Zealand populations were genetically different, and were different from the European and Asian populations. Our Bayesian coalescent analyses, based on a combination of novel and published sequence data from three non-recombinogenic protein-encoding regions, showed that TuMV probably started to migrate from Europe to Australia and New Zealand more than 80 years ago, and that distinct populations arose as a result of evolutionary drivers such as recombination. The basal-B2 subpopulation in Australia and New Zealand seems to be older than those of the world-B2 and -B3 populations. To our knowledge, our study presents the first population genetic analysis of TuMV in Australia and New Zealand. We have shown that the time of migration of TuMV correlates well with the establishment of agriculture and migration of Europeans to these countries., (© 2015 The Authors.)