The tidal and longer-period circulation of Capricornia, Southern Great Barrier Reef

1987 ◽  
Vol 38 (4) ◽  
pp. 461 ◽  
Author(s):  
DA Griffin ◽  
JH Middleton ◽  
L Bode

Between June and December 1983, nine current meters and three water level recorders were deployed on the continental shelf and slope of the Capricornia Section of the Great Barrier Reef between Fraser Island (25�s.) and the mouth of the Capricorn Channel (23�s.) on the east coast of Australia. Tidal analyses of the hourly data set reveal an amplification of the semi-diurnal tides as they propagate north- westward into the Capricorn Channel. The results of a numerical model of tidal flow show excellent agreement with observations. The daily averaged (non-tidal) currents are highly variable and produce complex circulation patterns, but with a mean flow generally alongshore to the north-west. Comparisons with previous drifter studies and satellite-tracked buoy data suggest that the south-eastward flowing East Australian Current drives a large clockwise eddy, in the lee of the Swain Reefs, located east of the study region. It is postulated that this eddy, in addition to the generally north-westward wind stress, contributes to the north-westward flow within the study region. Temperatures recorded by the deployed instruments and temperature profiles from conductivity-temperature-depth casts confirm that tidal and longer period variablity contribute to upwelling onto the continental shelf.

Zootaxa ◽  
2021 ◽  
Vol 4918 (1) ◽  
pp. 1-116
Author(s):  
ANTHONY C. GILL ◽  
JOHN J. POGONOSKI ◽  
GLENN I. MOORE ◽  
JEFFREY W. JOHNSON

Australian species of the anthiadine genera Plectranthias and Selenanthias are reviewed. Twenty-two species of Plectranthias and two species of Selenanthias are recorded from Australian waters: Plectranthias sp. 1 from a seamount north of Middleton Reef and Norfolk Ridge, Tasman Sea; P. alleni Randall from off southwest Western Australia; P. azumanus (Jordan & Richardson) from off southwest Western Australia; P. bennetti Allen & Walsh from Holmes Reef, Coral Sea; P. cruentus Gill & Roberts from Lord Howe Island, and possibly off Stradbroke Island, Queensland; P. ferrugineus n. sp. from the North West Shelf and Arafura Sea; P. fourmanoiri Randall from Christmas Island and Holmes Reef, Coral Sea; P. grahami n. sp. from off central New South Wales, Tasman Sea; P. inermis Randall from Christmas Island; P. japonicus (Steindachner) from the Arafura Sea and North West Shelf; P. kamii Randall from the Coral Sea, Lord Howe Island and Christmas Island; P. lasti Randall & Hoese from the North West Shelf and off Marion Reef, Queensland; P. longimanus (Weber) from the Timor Sea, Great Barrier Reef, Coral Sea and southern Queensland; P. maculicauda (Regan) from southeastern Australia; P. mcgroutheri n. sp. from the North West Shelf; P. megalophthalmus Fourmanoir & Randall from northeast of the Whitsunday Islands, Queensland; P. melanesius Randall from southeastern Queensland and a seamount north of Middleton Reef; P. moretonensis n. sp. from off Stradbroke Island, Queensland; P. nanus Randall from the Cocos (Keeling) Islands, Christmas Island, Great Barrier Reef and Coral Sea; P. retrofasciatus Fourmanoir & Randall from the Great Barrier Reef; P. robertsi Randall & Hoese from off Queensland, Coral Sea; P. winniensis (Tyler) from the Great Barrier Reef and Coral Sea; Selenanthias analis Tanaka from the North West Shelf and Arafura Sea; and S. barroi (Fourmanoir) from west of Lihou Reef, Coral Sea. Five of the species represent new records for Australia: P. azumanus, P. kamii, P. megalophthalmus, P. melanesius and S. barroi. Previous records of P. megalophthalmus from the North West Shelf are based on misidentified specimens of P. lasti. Records of P. wheeleri from the North West Shelf are based on specimens here identified as P. mcgroutheri n. sp. A record of P. yamakawai Yoshino from Christmas Island is based on a misidentified specimen of P. kamii. Plectranthias retrofasciatus was previously recorded from the Great Barrier Reef as P. pallidus Randall & Hoese, here shown to be a junior synonym of P. retrofasciatus. Video-based records of P. kelloggi from the Great Barrier Reef appear to be based on P. retrofasciatus. Identification keys, diagnoses, character summaries, photographs and Australian distribution information are presented for all species. Full descriptions are provided for the new species and for those newly recorded from Australia. 


1986 ◽  
Vol 37 (5) ◽  
pp. 545 ◽  
Author(s):  
GL Pickard

At Davies Reef, flow over the east reef flat was unidirectional downwind at 10-20 cm s-1 with strong winds and smaller tides but was semi-diurnal tidal reversing at 5-15 cm s-1 with lighter winds and higher tides. The flood direction was to the south-east out of the lagoon and the ebb into the lagoon. Wave overtopping was estimated to contribute at least 40% of the flow over the reef flat-the first estimate of this component of flow over reef flats. Transit times over the reef flat were 30-170 min and flushing times for the east lagoon were estimated as ½ -1 day for strong winds to the north-west but 2-4 days for lighter winds. In the east lagoon, the upper-layer currents were semi-diurnal tidal reversing all the time at speeds up to 20 cm s-1, with longer-term net flow downwind at about 2 cm s-1 with strong winds but upwind at 0.2 cm s-1 with light winds. In the east passage, the strongly tidal currents (up to 60 cm s-1.) had a long-term net flow to the south at about 2 cm s-1 without any clear correlation with the wind.


1984 ◽  
Vol 1 (19) ◽  
pp. 16
Author(s):  
K.P. Stark ◽  
L. Bode ◽  
L.B. Mason

The Great Barrier Reef Region which constitutes the north-eastern continental shelf waters of Australia, is an area that is subject to both large astronomical tides and the passage of tropical cyclones (hurricanes). One section of this area, centred on Mackay, is characterised by particularly high tides, with a springs range of order 10 metres. Numerical hydrodynamic modelling is used in the present study to: (a) simulate the M tide to investigate possible effects of the reef barrier on tidal amplification; (b) simulate the passage of a tropical cyclone across the continental shelf; (c) investigate the effect and consequences of non-linear surge/tide interactions. The recent discovery of a major shipping route through the reef in this area and the continuing development of natural resources makes a much more detailed understanding of the region's hydrodynamics essential for coastal engineering.


Elem Sci Anth ◽  
2017 ◽  
Vol 5 ◽  
Author(s):  
Andrew C. Thomas ◽  
Andrew J. Pershing ◽  
Kevin D. Friedland ◽  
Janet A. Nye ◽  
Katherine E. Mills ◽  
...  

The northeastern North American continental shelf from Cape Hatteras to the Scotian Shelf is a region of globally extreme positive trends in sea surface temperature (SST). Here, a 33-year (1982–2014) time series of daily satellite SST data was used to quantify and map spatial patterns in SST trends and phenology over this shelf. Strongest trends are over the Scotian Shelf (>0.6°C decade–1) and Gulf of Maine (>0.4°C decade–1) with weaker trends over the inner Mid-Atlantic Bight (~0.3°C decade–1). Winter (January–April) trends are relatively weak, and even negative in some areas; early summer (May–June) trends are positive everywhere, and later summer (July–September) trends are strongest (~1.0°C decade–1). These seasonal differences shift the phenology of many metrics of the SST cycle. The yearday on which specific temperature thresholds (8° and 12°C) are reached in spring trends earlier, most strongly over the Scotian Shelf and Gulf of Maine (~ –0.5 days year–1). Three metrics defining the warmest summer period show significant trends towards earlier summer starts, later summer ends and longer summer duration over the entire study region. Trends in start and end dates are strongest (~1 day year–1) over the Gulf of Maine and Scotian Shelf. Trends in increased summer duration are >2.0 days year–1 in parts of the Gulf of Maine. Regression analyses show that phenology trends have regionally varying links to the North Atlantic Oscillation, to local spring and summer atmospheric pressure and air temperature and to Gulf Stream position. For effective monitoring and management of dynamically heterogeneous shelf regions, the results highlight the need to quantify spatial and seasonal differences in SST trends as well as trends in SST phenology, each of which likely has implications for the ecological functioning of the shelf.


1956 ◽  
Vol 7 (3) ◽  
pp. 317 ◽  
Author(s):  
R Endean ◽  
W Stephenson ◽  
R Kenny

The species composition and general ecology of intertidal organisms present at Heron Island, a coral cay in the Capricorn Group, are recorded in this paper. It was found that the general zonation picture on this Great Barrier Reef island differed markedly from that found previously at localities on the Queensland mainland (Endean, Kenny, and Stephenson 1956). In particular the mainland upper barnacle (Chthamalus) zone was not represented at Heron I., and the species forming the mainland lower barnacle zone (Tetraclita squamosa (Bruguiere) ) was replaced by a different species (Tetraclita vitiata Darwin). Also the characteristic algal zone of mainland localities was replaced by a lithothamnion-zoanthid-coral zone. In order to investigate the possibility of a gradual transition from the mainland type zonation to that found on the Great Barrier Reef, as exemplified by Heron I. zonation, the species composition and general ecology of intertidal organisms inhabiting a series of continental islands lying off the Queensland coast between lat. 16� and 22� S. were investigated. The fauna of these islands was found to be closely allied to that of the mainland. There was, however, an intrusion of corals and zoanthids on the more exposed of the islands visited which lie between lat. 20� and 22�S., and also on the more northerly of the islands visited. The biogeographical implications of these findings are discussed, and it is noted that the results of the present investigation support the contention of Whitley (1932) that a longitudinal division of the Queensland marine fauna into "Solanderian" and "Banksian" elements is warranted. Accounts are also given of the major environmental factors that might affect specific composition and zonation patterns at the localities investigated. Analyses of these have given much information on the general ecology and distribution of many Queensland intertidal species. Thls information is discussed. Of particular interest was the finding that the Peronian barnacle Tetraclita rosea (Krauss) has extended its range,to the north of the biogeographical boundary situated near lat. 25� S. by colonizing the more exposed of the continental islands.


2007 ◽  
Vol 65 (1-4) ◽  
pp. 417-429 ◽  
Author(s):  
John R. Siddorn ◽  
J. Icarus Allen ◽  
Jerry C. Blackford ◽  
Francis J. Gilbert ◽  
Jason T. Holt ◽  
...  

1981 ◽  
Vol 32 (5) ◽  
pp. 721 ◽  
Author(s):  
E Wolanski ◽  
B Ruddick

Currents and sea levels were measured at a number of locations in the Great Barrier Reef (GBR) lagoon from about 10 to 13� S., during the period October-December 1979. A strong non-tidal, low-frequency modulation of all sea-level and current data was found. The currents nearshore were driven northward by the wind, and then at least partially blocked by the dense network of reefs to the north of 10� s. The water then flowed southward in deeper water adjacent to the reef, driven by a longshore pressure gradient. The low- frequency sea-level data, though not the current records, showed northward phase propagation at speeds characteristic of a first-mode shelf wave trapped in the lagoon between the shore and the reef. Data are presented revealing the intrusion of low-salinity water, through Bligh Entrance, in the GBR lagoon, as a result of river discharges in the Gulf of Papua. It is suggested that low-frequency longshore currents may periodically flush these river plumes from the GBR lagoon and enhance interaction between reefs. In the Coral Sea in front of reef passages, the large horizontal velocities may result in forces upwelling by selective withdrawal and jet entrainment.


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