Potential mechanisms of influence of the Leeuwin Current eddy system on teleost recruitment to the Western Australian continental shelf

2007 ◽  
Vol 54 (8-10) ◽  
pp. 1129-1140 ◽  
Author(s):  
Daniel J. Gaughan
Keyword(s):  
Continental Shelf ◽  
Leeuwin Current ◽  
Western Australian

Observations of warming on the Western Australian continental shelf

2007 ◽  
Vol 58 (10) ◽  
pp. 914 ◽  
Author(s):  
Alan Pearce ◽  
Ming Feng
Keyword(s):  
Indian Ocean ◽  
Continental Shelf ◽  
Southern Oscillation ◽  
Warming Trend ◽  
Eastern Indian Ocean ◽  
The South ◽  
Leeuwin Current ◽  
South Eastern ◽  
The Past ◽  
Western Australian

Global temperature datasets indicate a warming trend in the south-eastern Indian Ocean of ~0.02°C year–1. This is supported by in situ temperature measurements at a coastal monitoring station on the Western Australian continental shelf that have shown a mean temperature rise of 0.013°C year–1 since 1951, corresponding to ~0.6°C over the past 5 decades. Measurements from three other shallow stations between 1985 and 2004 indicated warming trends of 0.026–0.034°C year–1. It is suggested that enhanced air–sea heat flux into the south-eastern Indian Ocean may be a key factor in the rising temperature trend. There has also been a steady rise in salinity over the past half-century. At interannual scales, coherent temperature variability at the various stations indicates that larger-scale processes are influencing the shelf waters and are linked with El Niño/Southern Oscillation (ENSO)-related events in coastal sea level and hence the Leeuwin Current.

Dynamics of the Ningaloo Current off Point Cloates, Western Australia

2006 ◽  
Vol 57 (3) ◽  
pp. 291 ◽  
Author(s):  
Mun Woo ◽  
Charitha Pattiaratchi ◽  
William Schroeder
Keyword(s):  
Numerical Model ◽  
Continental Shelf ◽  
Western Australia ◽  
Bottom Topography ◽  
Volume Transport ◽  
Relative Strength ◽  
Cross Sectional ◽  
Leeuwin Current ◽  
The North ◽  
Tropical Water

The Ningaloo Current (NC) is a wind-driven, northward-flowing current present during the summer months along the continental shelf between the latitudes of 22° and 24°S off the coastline of Western Australia. The southward flowing Leeuwin Current is located further offshore and flows along the continental shelf break and slope, transporting warm, relatively fresh, tropical water poleward. A recurrent feature, frequently observed in satellite images (both thermal and ocean colour), is an anti-clockwise circulation located offshore Point Cloates. Here, the seaward extension of the coastal promontory blocks off the broad, gradual southern shelf, leaving only a narrow, extremely steep shelf to the north. The reduction in the cross-sectional area, from the coast to the 50 m contour, between southward and northward of the promontory is ~80%. Here, a numerical model study is undertaken to simulate processes leading to the development of the recirculation feature offshore Point Cloates. The numerical model output reproduced the recirculation feature and indicated that a combination of southerly winds, and coastal and bottom topography, off Point Cloates is responsible for the recirculation. The results also demonstrated that stronger southerly winds generated a higher volume transport in the NC and that the recirculation feature was dependent on the wind speed, with stronger winds decreasing the relative strength of the recirculation.

scholarly journals GEOGRAPHICAL AND TEMPORAL MOVEMENTS OF HUMPBACK WHALES IN WESTERN AUSTRALIAN WATERS

2001 ◽  
Vol 41 (1) ◽  
pp. 749 ◽  
Author(s):  
K.C.S. Jenner ◽  
M-N.M. Jenner ◽  
K.A. McCabe
Keyword(s):  
Continental Shelf ◽  
General Framework ◽  
Group Iv ◽  
Humpback Whales ◽  
Shark Bay ◽  
Migratory Path ◽  
Migratory Route ◽  
Temporal And Spatial ◽  
Exmouth Gulf ◽  
Western Australian

Through compilation of historical whaling data, together with recent aerial and boat-based survey data, a general framework for the overall peaks of migration has been estimated for the temporal and spatial movements of Group IV humpback whales along the Western Australian coast.The migratory paths of humpback whales along the Western Australian coast lie within the continental shelf boundary or 200 m bathymetry. Major resting areas along the migratory path have been identified at Exmouth Gulf (southern migration only) and at Shark Bay. The northern endpoint of migration and resting area for reproductively active whales in the population appears to be Camden Sound in the Kimberley. A 6,750 square km2 area of the Kimberley region, inclusive of Camden Sound, has also been identified as a major calving ground. The northern and southern migratory paths have been shown to be divergent at the Perth Basin, Dampier Archipelago and Kimberley regions. In all cases the northern migratory route is further off-shore.

Altivasum Hedley, 1914 (Gastropoda: Turbinellidae) from South Western Australia

The Festivus ◽  
2018 ◽  
Vol 50 (4) ◽  
pp. 245-255
Author(s):  
Aart Dekkers ◽  
Stephen Maxwell
Keyword(s):  
Continental Shelf ◽  
Western Australia ◽  
Distinct Species ◽  
Current Understanding ◽  
The South ◽  
Geographic Separation ◽  
Western Side ◽  
Morphological Differences ◽  
Great Australian Bight ◽  
Western Australian

This paper seeks to correct the erroneous taxonomy associated with the current understanding of the Altivasum flindersi (Verco, 1914) complex based on type revision, morphological differences and geographic separation. Structurally, there are three distinct species that can be differentiated, Altivasum flindersi (Verco, 1914), A. typicum Hedley, 1916 and A. profundum sp. nov. Geographically, these species are not all sympatric, with A. typicum restricted to shallower waters, at depths around 20-180 m off the south Western Australian coast, whereas A. profundum is located at the edge of the South Western Australian continental shelf, and A. flindersi is found off the coast of the Great Australian Bight at similar depths to A. typicum. There is an overlap in distribution between A. typicum Hedley, 1916 and A. flindersi (Verco, 1914) on the western side of the Great Australian Bight where they are often associated with similar habitats.

Dipole vortices in the Great Australian Bight

2015 ◽  
Vol 66 (2) ◽  
pp. 135 ◽  
Author(s):  
George R. Cresswell ◽  
Lars C. Lund-Hansen ◽  
Morten Holtegaard Nielsen
Keyword(s):  
Surface Temperature ◽  
Continental Shelf ◽  
Sea Surface Temperature ◽  
Sea Surface ◽  
The South ◽  
Leeuwin Current ◽  
A Chain ◽  
Salinity Difference ◽  
Great Australian Bight

Shipboard measurements from late 2006 made by the Danish Galathea 3 Expedition and satellite sea surface temperature images revealed a chain of cool and warm ‘mushroom’ dipole vortices that mixed warm, salty, oxygen-poor waters on and near the continental shelf of the Great Australian Bight (GAB) with cooler, fresher, oxygen-rich waters offshore. The alternating ‘jets’ flowing into the mushrooms were directed mainly northwards and southwards and differed in temperature by only 1.5°C; however, the salinity difference was as much as 0.5, and therefore quite large. The GAB waters were slightly denser than the cooler offshore waters. The field of dipoles evolved and distorted, but appeared to drift westwards at 5km day–1 over two weeks, and one new mushroom carried GAB water southwards at 7km day–1. Other features encountered between Cape Leeuwin and Tasmania included the Leeuwin Current, the South Australian Current, the Flinders Current and the waters of Bass Strait.

scholarly journals Seasonal and inter-annual variability of water column properties along the Rottnest continental shelf, south-west Australia

Ocean Science ◽  
2019 ◽  
Vol 15 (2) ◽  
pp. 333-348 ◽  
Author(s):  
Miaoju Chen ◽  
Charitha B. Pattiaratchi ◽  
Anas Ghadouani ◽  
Christine Hanson
Keyword(s):  
Chlorophyll Fluorescence ◽  
Continental Shelf ◽  
Water Column ◽  
Inner Shelf ◽  
Leeuwin Current ◽  
Enso Events ◽  
Annual Variability ◽  
South West ◽  
Basin Scale ◽  
Autumn And Winter

Abstract. A multi-year ocean glider dataset, obtained along a representative cross-shelf transect along the Rottnest continental shelf, south-west Australia, was used to characterise the seasonal and inter-annual variability of water column properties (temperature, salinity, and chlorophyll fluorescence distribution). All three variables showed distinct seasonal and inter-annual variations that were related to local and basin-scale ocean atmosphere processes. Controlling influences for the variability were attributed to forcing from two spatial scales: (1) the local scale (due to Leeuwin Current and dense shelf water cascades, DSWC) and (2) the basin scale (El Niño–Southern Oscillation, ENSO, events). In spring and summer, inner-shelf waters were well mixed due to strong wind mixing, and deeper waters (>50 m) were vertically stratified in temperature that contributed to the presence of a subsurface chlorophyll maximum (SCM). On the inner shelf, chlorophyll fluorescence concentrations were highest in autumn and winter. DSWCs were also the main physical feature during autumn and winter. Chlorophyll fluorescence concentration was higher closer to the seabed than at the surface in spring, summer, and autumn. The seasonal patterns coincided with changes in the wind field (weaker winds in autumn) and air–sea fluxes (winter cooling and summer evaporation). Inter-annual variation was associated with ENSO events. Lower temperatures, higher salinity, and higher chlorophyll fluorescence (>1 mg m−3) were associated with the El Niño event in 2010. During the strong La Niña event in 2011, temperatures increased and salinity and chlorophyll fluorescence decreased (<1 mg m−3). It is concluded that the observed seasonal and inter-annual variabilities in chlorophyll fluorescence concentrations were related to the changes in physical forcing (wind forcing, Leeuwin Current, and air–sea heat and moisture fluxes).

scholarly journals Condition of larvae of western rock lobster (Panulirus cygnus) in cyclonic and anticyclonic eddies of the Leeuwin Current off Western Australia

2015 ◽  
Vol 66 (12) ◽  
pp. 1158 ◽  
Author(s):  
Miao Wang ◽  
Richard O'Rorke ◽  
Anya M. Waite ◽  
Lynnath E. Beckley ◽  
Peter Thompson ◽  
...  
Keyword(s):  
Western Australia ◽  
Spiny Lobster ◽  
Dry Mass ◽  
Leeuwin Current ◽  
Dramatic Decline ◽  
Biochemical Analyses ◽  
Panulirus Cygnus ◽  
Anticyclonic Eddies ◽  
Western Australian ◽  
Stage Viii

Changes in the offshore oceanographic processes are suspected to be the cause of a recent dramatic decline in the settlement of post-larvae of the Western Australian spiny lobster (Panulirus cygnus), which has greatly reduced the productivity from the world’s second-largest spiny lobster fishery. The present study assessed whether there are differences in the nutritional condition of the larvae of P. cygnus sampled from two pairs of cyclonic eddies (CEs) and anticyclonic eddies (AEs). Morphometric and biochemical analyses were undertaken on the mid–late-stage larvae (VI, VII, VIII) sampled offshore from two pairs of adjacent counter-rotating mesoscale eddies in the Leeuwin Current off Western Australia. The results showed that larvae captured from CEs had greater average total dry mass (P<0.001) than those from AEs. Stage VIII larvae from CEs contained more protein (P<0.008) (38.5% ±5.4s.e.) and lipid (P<0.005) (67.2% ±12.1) than did those from AEs. The possible causes for these differences are uncertain but may be related to differences in water temperatures in CEs v. AEs influencing the ability of phyllosomas to accumulate nutritional reserves.

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