Observations of a new Baroclinic current along the western continental slope of Bass Strait

Baines, PG; Edwards, RJ; Fandry, C. B.

doi:10.1071/mf9830155

Cited by 40 publications

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References 3 publications

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“…70 m below present sea level). The major continental boundary currents, East Australian Current and Zeehan Current, are shown (Baines et al ., ; Cresswell, ). INSET MAP showing the three marine biogeographical provinces in southern temperate Australian waters: Flindersian (western), Peronian (eastern) and Maugean (Bassian), as proposed by Bennett & Pope () with major oceanic currents indicated (modified from Li et al ., ).…”

Section: Introductionmentioning

confidence: 99%

Genetic signatures of Bassian glacial refugia and contemporary connectivity in a marine foundation species

Sinclair

Anthony

Greer

et al. 2016

Journal of Biogeography

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Aim To examine the population genetic structure in Posidonia australis meadows, a marine foundation species capable of long distance dispersal (LDD), and the role of historical versus contemporary processes in shaping post Last Glacial Maximum (LGM) re‐colonization. Location Southeastern Australia including the Bass Strait Islands. Methods We generated multilocus genotypes and assessed spatial patterns of genetic diversity. Relationships among meadows were assessed in terms of historical sea level changes, oceanic boundary currents and contemporary seed dispersal based on a hydrodynamic model. Results There was strong regional spatial genetic structuring among P. australis meadows in south‐eastern Australia, which was congruent with three recognized marine biogeographical provinces [Peronian (eastern), Flindersian (western and southern), and Maugean (south‐eastern)]. The genetic data suggest Maugean meadows persisted in isolation during the LGM, with evidence for admixture and contemporary gene flow. Simulated dispersal events identified high rates of local and regional demographic connectivity, with evidence for occasional LDD events. Main conclusions The strong regional differentiation is consistent with long‐term barriers to dispersal persisting in the marine environment through many sea level fluctuations. Bass Strait Island meadows all have strong signals of genetic admixture. A weak but significant isolation by distance relationship is consistent with a historical signal and contemporary seed dispersal mostly within the Bass Strait.

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Section: Introductionmentioning

confidence: 99%

Genetic signatures of Bassian glacial refugia and contemporary connectivity in a marine foundation species

Sinclair

Anthony

Greer

et al. 2016

Journal of Biogeography

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“…The Leeuwin Current arises in warm Indonesian waters and in winter flows south along the coast of Western Australia and east into the Great Australian Bight. From here it is replaced by the warm saline Great Australian Bight Current (Rochford, 1986) and then by the weaker Zeehan Current which runs as far east as western Tasmania (Baines, Edwards & Fandry, 1983). The East Australian Current flows from the northern Tasman Sea, south along the coast of Queensland and New South Wales before veering off near 33° S into the Tasman Sea.…”

Section: Introductionmentioning

confidence: 99%

Patterns of distribution for southern Australian marine echinoderms and decapods

O'Hara

Poore

2000

Journal of Biogeography

113

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Aim To relate patterns of distribution of marine echinoderms and decapods around southern Australia to major ecological and historical factors. Location Shallow‐water (0–100 m) marine waters off southern Australia, south of 30° S. Methods (1) Record the presence/absence of known echinoderm and decapod species in cells of c. 1° latitude and longitude, along the coast of southern mainland Australia and Tasmania. (2) Describe patterns in species composition, species richness and endemism through gradient analysis, ordination and cluster analysis. (3) Relate these patterns to distance and temperature gradients, the area of continental shelf, the average size of species range, and known historical factors. Results Species composition varied with both latitude and longitude. Species richness was relatively constant from east to west but graded with latitude from high in the warm‐temperate regions around Perth and Sydney to low in cool‐temperate southern Tasmania. Species richness was not related to the area of continental shelf or average species range size. Species turnover was not correlated with rates of temperature change. It was problematic to separate distance from temperature gradients, but there was evidence that the southern distribution limits of some species are related to minimum sea surface temperature. Within the taxonomic groups surveyed, evolutionary radiation has been largely limited to a few cosmopolitan species‐rich genera. Main conclusions There are historical as well as ecological hypotheses explaining the latitudinal gradient of marine species richness in southern Australia: (1) the continual invasion and speciation of species of tropical origin as Australia has split from Gondwana and drifted northward; (2) progressive extinction of some Gondwanan cool‐temperate species at the limits of their range; (3) low level of immigration of additional cool‐temperate species; and (4) some in situ endemic speciation.

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“…1) mix into the Subantarctic Zone, and also meet Zeehan Current (ZC, Fig. 1) waters transported down the west coast of Tasmania (Boland and Church, 1981;Baines et al, 1983;Speich et al, 2002;Davis, 2005;Ridgway et al, 2007;Sloyan et al, 2016). The EAC transported south of Tasmania forms a zonal jet towards the south-east Indian Ocean, known as the Tasman Outflow, that reaches the bottom of the Tasman slope and that is maintained all year round (Rintoul and Bullister, 1999;Ridgway et al, 2007).…”

Section: Hydrography Of the Regionmentioning

confidence: 99%

Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

et al. 2017

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Abstract. Biogeochemical change in the water masses of the Southern Ocean, south of Tasmania, was assessed for the 16-year period between 1995 and 2011 using data from four summer repeats of the WOCE-JGOFS-CLIVAR-GO-SHIP (Key et al., 2015;Olsen et al., 2016) SR03 hydrographic section (at ∼ 140 • E). Changes in temperature, salinity, oxygen, and nutrients were used to disentangle the effect of solubility, biology, circulation and anthropogenic carbon (C ANT ) uptake on the variability of dissolved inorganic carbon (DIC) for eight water mass layers defined by neutral surfaces (γ n ). C ANT was estimated using an improved back-calculation method. Warming (∼ 0.0352 ± 0.0170 • C yr −1 ) of Subtropical Central Water (STCW) and Antarctic Surface Water (AASW) layers decreased their gas solubility, and accordingly DIC concentrations increased less rapidly than expected from equilibration with rising atmospheric CO 2 (∼ 0.86 ± 0.16 µmol kg −1 yr −1 versus ∼ 1 ± 0.12 µmol kg −1 yr −1 ). An increase in apparent oxygen utilisation (AOU) occurred in these layers due to either remineralisation of organic matter or intensification of upwelling. The range of estimates for the increases in C ANT were 0.71 ± 0.08 to 0.93 ± 0.08 µmol kg −1 yr −1 for STCW and 0.35 ± 0.14 to 0.65 ± 0.21 µmol kg −1 yr −1 for AASW, with the lower values in each water mass obtained by assigning all the AOU change to remineralisation. DIC increases in the Sub-Antarctic Mode Water (SAMW, 1.10 ± 0.14 µmol kg −1 yr −1 ) and Antarctic Intermediate Water (AAIW, 0.40 ± 0.15 µmol kg −1 yr −1 ) layers were similar to the calculated C ANT trends. For SAMW, the C ANT increase tracked rising atmospheric CO 2 . As a consequence of the general DIC increase, decreases in total pH (pH T ) and aragonite saturation ( Ar ) were found in most water masses, with the upper ocean and the SAMW layer presenting the largest trends for pH T decrease (∼ −0.0031 ± 0.0004 yr −1 ). DIC increases in deep and bottom layers (∼ 0.24 ± 0.04 µmol kg −1 yr −1 ) resulted from the advection of old deep waters to resupply increased upwelling, as corroborated by increasing silicate (∼ 0.21 ± 0.07 µmol kg −1 yr −1 ), which also reached the upper layers near the Antarctic Divergence (∼ 0.36 ± 0.06 µmol kg −1 yr −1 ) and was accompanied by an increase in salinity. The observed changes in DIC over the 16-year span caused a shoaling (∼ 340 m) of the aragonite saturation depth (ASD, Ar = 1) within Upper Circumpolar Deep Water that followed the upwelling path of this layer. From all our results, we conclude a scenario of increased transport of deep waters into the section and enhanced upwelling at high latitudes for the period between 1995 and 2011 linked to strong westerly winds. Although enhanced upwelling lowered the capacity of the AASW layer to uptake atmospheric CO 2 , it did not limit that of the newly forming SAMW and AAIW, which exhibited C ANT storage rates (∼ 0.41 ± 0.20 mol m −2 yr −1 ) twice that of the upper layers.

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Observations of a new Baroclinic current along the western continental slope of Bass Strait

Cited by 40 publications

References 3 publications

Genetic signatures of Bassian glacial refugia and contemporary connectivity in a marine foundation species

Genetic signatures of Bassian glacial refugia and contemporary connectivity in a marine foundation species

Patterns of distribution for southern Australian marine echinoderms and decapods

Carbon uptake and biogeochemical change in the Southern Ocean, south of Tasmania

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