Some zooplankton characteristics of warm-core eddies shed by the East Australian Current, with particular reference to copepods

1983 ◽  
Vol 34 (4) ◽  
pp. 587 ◽  
Author(s):  
DJ Tranter ◽  
DJ Tafe ◽  
RL Sandland
Keyword(s):  
Free Fall ◽  
Dry Weight ◽  
Physical Structure ◽  
East Australian Current ◽  
The South ◽  
Warm Core ◽  
Tasman Sea

Several eddies in the south-western Tasman Sea were investigated to see whether they differed faunistically from the seas around them. Zooplankton samples (0-200 m) were taken by free-fall net for dry weight measurements and copepod analyses. The counts obtained for 20 species of copepod were used to classify 51 stations into (eight) groups. These were taken to constitute the major zooplankton habitats in the study area. These habitats corresponded in most respects with the known physical structure of the study area. Eddies were faunistically distinct from the seas that surrounded them. Eddy J was similar in 1979-1980 to the waters of the East Australian Current, which were periodically entrained within the eddy circulation. There were significant faunal differences between eddy J and eddy F, an isolated eddy sampled in December 1978.

Bass Strait water intrusions in the Tasman Sea and mean temperature-salinity curves

1981 ◽  
Vol 32 (5) ◽  
pp. 699 ◽  
Author(s):  
M Tomczak Jr
Keyword(s):  
Water Mass ◽  
East Australian Current ◽  
Shelf Edge ◽  
The South ◽  
The North ◽  
Mean Temperature ◽  
Tasman Sea

At temperatures of 8-18�C mean temperature-salinity curves for the Tasman Sea show slightly higher salinities in the south than in the north. It is shown that this is the effect of intrusions of Bass Strait Water which enters the Tasman Sea predominantly in winter and can be traced in individual stations over distances of 600 nautical miles along the shelf edge and 200 nautical miles offshore. The paths of individual intrusions and the degree of mixing are highly variable and seem to depend, among other factors, on the path of the East Australian Current and its eddies. This is interpreted as an indication that the eddies may play a major role in the formation of the water-mass characteristics of the Tasman Sea.

Physical evolution of Tasman Sea Eddy J

1983 ◽  
Vol 34 (4) ◽  
pp. 495 ◽  
Author(s):  
GR Cresswell
Keyword(s):  
Mixed Layer ◽  
East Australian Current ◽  
Surface Mixed Layer ◽  
Deep Surface ◽  
Warm Core ◽  
Tasman Sea ◽  
Observation Period ◽  
Subsequent Identification

The evolution of warm-core eddy J was followed from March 1979 until May 1980. From March to October 1979, eddy J developed a deep surface mixed layer that, after summer capping, became a subsurface 'signature' for subsequent identification. During the first half of the observation period, eddy J was subjected to frequent peripheral injections of northern water, mainly from the East Australian Current but on one occasion from a northern eddy. Between mid-December 1979 and early February 1980, the signature layer of eddy J moved on top of the signature layer of another eddy. This is suggested to be an indication of the coalescence of the two eddies. The prehistory of eddy J was conjectured from the nature of a signature layer that the eddy already had in March 1979.

On the climatology of warm-core rings from the East Australian Current

1983 ◽  
Vol 34 (4) ◽  
pp. 687 ◽  
Author(s):  
PJ Mulhearn
Keyword(s):  
Standard Deviation ◽  
Geographical Distribution ◽  
Mixed Layer ◽  
Past Research ◽  
East Australian Current ◽  
Surface Mixed Layer ◽  
The South ◽  
Mean Values ◽  
Warm Core

The observed geographical distribution of warm-core rings is discussed in relation to the coverage of past research cruises. It is found that no rings, detached from the East Australian Current, have been found north of 33�S. and that there is a tendency for them to persist for some time to the south- east of Jervis Bay between 35 and 38�S. and 151 and 154�E. Surface mixed-layer temperatures are similar to monthly mean values over 10 years, being 0.35�C higher on average with a standard deviation of 1.0�C. Surface mixed-layer depths within rings are significantly greater than the average values found at 34�S. from February to September but are close to the average values in November and December.

Geographical distribution of living planktonic foraminifera (Protozoa) off the east coast of Australia.

1988 ◽  
Vol 39 (1) ◽  
pp. 71 ◽  
Author(s):  
S Andrijanic
Keyword(s):  
Sea Water ◽  
Planktonic Foraminifera ◽  
Distribution Patterns ◽  
Water Masses ◽  
Individual Species ◽  
The South ◽  
The North ◽  
Warm Core ◽  
Tasman Sea ◽  
Eastern Australia

Major water masses found off eastern Australia can be identified by their planktonic foraminiferal faunas. A total of 83 surface and oblique plankton samples from two cruises, in spring (October) and summer (January), between Hobart at 44� S. and Townsville at 18� S. yielded 27 species belonging to four distinct faunas: 'tropical', 'warm subtropical', 'cool subtropical' and 'transitional'. The tropical fauna is characterized by Globigerinoides sacculifer at an abundance greater than 42% and the co- dominance of Globigerinoides conglobatus, and is associated with Coral Sea water of equatorial origin. The subtropical fauna can be subdivided into warm and cool elements. The warm-subtropical fauna, with G. sacculifer more abundant than Globigerinoides ruber, inhabits Coral and Tasman Sea waters. The cool-subtropical fauna is a mixture of the warm subtropical and the transitional faunas. The transitional fauna is dominated by Globorotalia inflata and Globigerina bulloides in the south Tasman Sea subantarctic waters. It characterizes the South West Tasman water as defined by Rochford (1957). These water masses can be clearly separated, and the extent of mixing determined by their foraminiferal fauna. The shifts in the boundaries between the faunal zones was evident between spring and summer. The boundary between the tropical and subtropical water corresponds to the tropical convergence and the subtropical/transitional boundary is the Tasman Front. During the spring cruise, a warm core eddy was identified by its warm subtropical foraminiferal fauna surrounded by a transitional fauna to the south and cool subtropical fauna to the north. This water body was near 32� S., which is consistent with the reported positions of eddies shed by the East Australian Current. The distribution patterns of individual species are discussed.

Origins of water within warm-core eddies of the western Tasman Sea

1983 ◽  
Vol 34 (4) ◽  
pp. 525 ◽  
Author(s):  
DJ Rochford
Keyword(s):  
High Salinity ◽  
East Australian Current ◽  
Surrounding Water ◽  
Warm Core ◽  
Tasman Sea ◽  
The Face

Comparison of the salinity within and around warm-core eddies of the western Tasman Sea has shown (a) that such eddies have their origin solely within waters of the East Australian Current (EAC); (b) that as these eddies drift southward within the EAC, their salinity characteristics differ little from those of the surrounding water; (c) that after separation from the EAC at around 34�S., their salinity characteristics are generally conserved in the face of much lower salinities of the surrounding waters. This latter feature was especially marked in the case of eddy J, which maintained in the upper 250 m an abnormally high salinity signature to as far south as 40� Below 300 m, this eddy J contained remnants of another high-salinity eddy. Possible derivations of these deeper waters are examined.

Isothermal temperatures and transformations of the warm-core eddies in the western Tasman Sea

1983 ◽  
Vol 34 (4) ◽  
pp. 681 ◽  
Author(s):  
D Airey
Keyword(s):  
Ad Hoc ◽  
Eastern Coast ◽  
East Australian Current ◽  
Isothermal Temperature ◽  
Warm Core ◽  
Tasman Sea

Warm-core eddies off the eastern coast of Australia are characterized by their isothermal core temperatures. For coastal eddies, core temperatures correlate with the latitude of the eddy at the end of winter. The isothermal temperature is used to identify and track eddies. Eddy positions from 1976 to 1981 have been charted to show patterns in their formation, drift and interactions with other eddies and the East Australian Current. To date, eddies have been named alphabetically in an ad hoc way that has caused confusion because of the unexpected behaviour of some eddies. To overcome this, a systematic way of naming eddies is suggested, which takes into account the eddy's history.

Edge enrichment in an ocean eddy

1983 ◽  
Vol 34 (4) ◽  
pp. 665 ◽  
Author(s):  
DJ Tranter ◽  
GS Leech ◽  
D Airey
Keyword(s):  
Bluefin Tuna ◽  
Anticyclonic Eddy ◽  
The South ◽  
Cool Water ◽  
Warm Core ◽  
Low Concentrations ◽  
Tasman Sea ◽  
Circulation Cell ◽  
Southern Bluefin Tuna ◽  
High Concentrations

In October 1981, relatively high concentrations of surface phytoplankton (chlorophyll a~1.5 �g1-1 relative to a background of ~0.4 �g 1-1) were observed in a cyclonic crescent of cool water along the south-eastern margin of a warm-core eddy in the south-westem Tasman Sea. Associated with this phytoplankton peak were relatively high concentrations of surface nitrate (~50�g I-1), low concentrations of oxygen (<90% satn), and a population of a copepod (Calanoides carinatus) often associated with upwellings. The salinity, oxygen and nitrate distributions suggest that an upwelling-downwelling circulation cell existed at the interface between (anticyclonic) eddy and (cyclonic) crescent. Biological enrichment was greater at the site of the crescent than where the margin of the eddy was comparatively straight. The hypothesis is advanced that such enrichment may be the basis for the association that exists between schools of southern bluefin tuna and sharp surface temperature fronts.

scholarly journals The Role of the New Zealand Plateau in the Tasman Sea Circulation and Separation of the East Australian Current

2018 ◽  
Vol 123 (2) ◽  
pp. 1457-1470 ◽  
Author(s):  
Christopher Y. S. Bull ◽  
Andrew E. Kiss ◽  
Erik van Sebille ◽  
Nicolas C. Jourdain ◽  
Matthew H. England
Keyword(s):  
New Zealand ◽  
East Australian Current ◽  
Tasman Sea
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