Glacial Troughs Drive Shelf/Slope Exchange

Data acquired during a winter (May) cruise of the RV Franklin to the southern Great Barrier Reef indicate that the dynamics of the shelf/slope region are governed by the tides, the poleward-flowing East Australian Current (EAC), and the complex topography. Over the Marion Plateau in water deeper than - 100 m, the EAC appears to drive a slow clockwise circulation. Tides appear to be primarily responsible for shelf/slope currents in the upper layers, with evidence of nutrient uplift from the upper slope to the outer shelf proper in the Capricorn Channel. Elsewhere, the bottom Ekrnan flux of the strongly poleward-flowing EAC enhances the sloping isotherms associated with the longshore geostrophic balance, pumping nutrient-rich waters from depth to the upper continental slope. Generally, shelf waters are cooler than oceanic waters as a consequence of surface heat loss by radiation. A combination of heat loss and evaporation from waters flowing in the shallows of the Great Sandy Strait appears to result in denser 'winter mangrove waters' exporting low-oxygen, high-nutrient waters onto the shelf both north and south of Fraser Island; these subsequently mix with shelf waters and finally flow offshore at - 100 m depth, just above the salinity-maximum layer, causing anomalous nutrient values in the region of Fraser Island.

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Odontopleura (Trilobita, Silurian), and a method of constrained congruency analysis

Journal of Paleontology ◽

10.1017/s0022336000042645 ◽

1990 ◽

Vol 64 (4) ◽

pp. 600-614 ◽

Cited By ~ 13

Author(s):

Jonathan M. Adrain ◽

Brian D. E. Chatterton

Keyword(s):

Cladistic Analysis ◽

Canadian Arctic ◽

Wide Distribution ◽

Parsimony Analysis ◽

Directed Tree ◽

Shelf Slope ◽

Major Species ◽

Species Groups ◽

The Universe ◽

A New Species

Odontopleura (Odontopleura) arctica, a new species of odontopleurine trilobite, is described from the Canadian Arctic. A method of cladistic analysis is detailed. Parsimony analysis should be performed treating all characters as unordered. The universe of directed trees implied by the resulting rootless network(s) can then be examined and a preferred tree selected by a criterion of congruency. Namely, the most parsimonious directed tree that accommodates the most congruent arrangement of character-states should be taken as the preferred cladogram. Since this is essentially a general congruency method operating within the constraints of parsimony, it is termed “constrained congruency.” The method is applied to the genus Odontopleura, resulting in the recognition of two major species groups, the nominate subgenus and Sinespinaspis n. subgen. Odontopleura (Ivanopleura) dufrenoyi Barrande is tentatively included in the genus, but considered too poorly known for cladistic analysis. Species assigned to Odontopleura (Odontopleura) include Odontopleura ovata Emmrich, Odontopleura brevigena Chatterton and Perry, Odontopleura (Odontopleura) arctica n. sp., and Diacanthaspis serotina Apollonov. Species assigned to Sinespinaspis n. subgen. include Taemasaspis llandoveryana Šnajdr, Odontopleura greenwoodi Chatterton and Perry, Odontopleura maccallai Chatterton and Perry, and Odontopleura nehedensis Chatterton and Perry. Odontopleura bombini Chatterton and Perry is tentatively placed in synonymy with Odontopleura nehedensis. The genus had a wide distribution throughout the Early and Middle Silurian, due to preferences for deep-water, distal shelf or shelf-slope transition zone habitats.

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Acoustic imaging of the New England shelf-slope water mass interfaces

Nature ◽

10.1038/269790a0 ◽

1977 ◽

Vol 269 (5631) ◽

pp. 790-791 ◽

Cited By ~ 2

Author(s):

FRED C. NEWMAN ◽

JOHN R. PRONI ◽

DONALD J. WALTER ◽

H. MICHAEL BYRNE

Keyword(s):

New England ◽

Water Mass ◽

Acoustic Imaging ◽

Shelf Slope

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Benthic macrofaunal production for a typical shelf–slope–basin region in the western Arctic Ocean

Continental Shelf Research ◽

10.1016/j.csr.2015.12.001 ◽

2016 ◽

Vol 113 ◽

pp. 30-37 ◽

Cited By ~ 5

Author(s):

Heshan Lin ◽

Jianjun Wang ◽

Kun Liu ◽

Xuebao He ◽

Junhui Lin ◽

...

Keyword(s):

Arctic Ocean ◽

Western Arctic Ocean ◽

Shelf Slope ◽

Western Arctic ◽

Basin Region

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M2 tidal dynamics in the Ross Sea

Antarctic Science ◽

10.1017/s0954102003001044 ◽

2003 ◽

Vol 15 (1) ◽

pp. 41-46 ◽

Cited By ~ 13

Author(s):

ROBIN ROBERTSON ◽

AIKE BECKMANN ◽

HARTMUT HELLMER

Keyword(s):

Continental Shelf ◽

Ross Sea ◽

Tidal Energy ◽

Ocean Model ◽

Internal Tides ◽

Global Ocean ◽

Tidal Dynamics ◽

Tidal Elevation ◽

Shelf Slope ◽

Continental Shelf Slope

In certain regions of the Southern Ocean, tidal energy is believed to foster the mixing of different water masses, which eventually contribute to the formation of deep and bottom waters. The Ross Sea is one of the major ventilation sites of the global ocean abyss and a region of sparse tidal observations. We investigated M2 tidal dynamics in the Ross Sea using a three-dimensional sigma coordinate model, the Regional Ocean Model System (ROMS). Realistic topography and hydrography from existing observational data were used with a single tidal constituent, the semi-diurnal M2. The model fields faithfully reproduced the major features of the tidal circulation and had reasonable agreement with ten existing tidal elevation observations and forty-two existing tidal current measurements. The differences were attributed primarily to topographic errors. Internal tides were generated at the continental shelf/slope break and other areas of steep topography. Strong vertical shears in the horizontal velocities occurred under and at the edges of the Ross Ice Shelf and along the continental shelf/slope break. Estimates of lead formation based on divergence of baroclinic velocities were significantly higher than those based on barotrophic velocities, reaching over 10% at the continental shelf/slope break.

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