The Spreading of Lower Circumpolar Deep Water in the Atlantic Ocean

The SW Indian Ocean contains at least four layers of water masses with different sources: deep Antarctic (Lower Circumpolar Deep Water) flow to the north, midwater North Indian Deep Water flow to the south and Upper Circumpolar Deep Water to the north, meridional convergence of intermediate waters at 500–1500 m, and the shallow South Equatorial Current flowing west. Sedimentation rates in the area are rather low, being less than 1 cm ka −1 on Madagascar Ridge, but up to 4 cm ka −1 at Amirante Passage. Bottom flow through the Madagascar–Mascarene Basin into Amirante Passage varies slightly on glacial–interglacial time–scales, with faster flow in the warm periods of the last interglacial and minima in cold periods. Far more important are the particularly high flow rates, inferred from silt grain size, which occur at warm–to–cold transitions rather than extrema. This suggests the cause is changing density gradient driving a transiently fast flow. Corroboration is found in the glacial–interglacial range of benthic d 18 O which is ca. 2%, suggesting water close to freezing and at least 1.2 more saline and thus more dense glacial bottom waters than present. Significant density steps are inferred in isotope stage 6, the 5e–5d, and 5a–4 transitions. Oxygen isotope data suggest little change by mixing in glacial bottom water on their northward path. Benthic carbon isotope ratios at Amirante Passage differ from glacial Southern Ocean values, due possibly to absence of a local productivity effect present in the Southern Ocean.

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Lower Circumpolar Deep Water Flow Through the SW Pacific Gateway for the Last 190 Ky: Evidence from Antarctic Diatoms

Geophysical Monograph Series - The Oceans and Rapid Climate Change ◽

10.1029/gm126p0101 ◽

2013 ◽

pp. 101-116 ◽

Cited By ~ 5

Author(s):

Catherine E. Stickley ◽

Lionel Carter ◽

I. Nick Mccave ◽

Phil P.E. Weaver

Keyword(s):

Water Flow ◽

Deep Water ◽

Circumpolar Deep Water ◽

Sw Pacific ◽

Lower Circumpolar Deep Water ◽

Flow Through ◽

Antarctic Diatoms

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Antarctic bottom and lower circumpolar deep water circulation in the eastern Indian Ocean

Journal of Geophysical Research Atmospheres ◽

10.1029/2005jc003011 ◽

2006 ◽

Vol 111 (C2) ◽

Cited By ~ 26

Author(s):

Bernadette M. Sloyan

Keyword(s):

Indian Ocean ◽

Deep Water ◽

Water Circulation ◽

Eastern Indian Ocean ◽

Circumpolar Deep Water ◽

Lower Circumpolar Deep Water

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Bougainvillia aberrans (Cnidaria, Hydrozoa), a new species of hydroid and medusa from the upper bathyal zone off Bermuda

Canadian Journal of Zoology ◽

10.1139/z93-132 ◽

1993 ◽

Vol 71 (5) ◽

pp. 997-1002 ◽

Cited By ~ 3

Author(s):

Dale R. Calder

Keyword(s):

New Species ◽

Atlantic Ocean ◽

North Atlantic ◽

Deep Water ◽

North Atlantic Ocean ◽

Deep Water Species ◽

A New Species ◽

Water Species

Bougainvillia aberrans n.sp. is described from Bermuda in the western North Atlantic Ocean. Specimens were collected at a depth of 150 fathoms (274 m) from the polypropylene buoy line of a crab trap. The hydroid colony of B. aberrans is erect, with a polysiphonic hydrocaulus, a smooth to somewhat wrinkled perisarc, hydranths having a maximum of about 16 tentacles, and medusa buds arising only from hydranth pedicels. Medusae liberated in the laboratory from these hydroids differ from all other known species of the genus in having a long, spindle-shaped manubrium, lacking oral tentacles, having marginal tentacles reduced to mere stubs, and being very short-lived (surviving for a few hours at most). Gonads develop in medusa buds while they are still attached to the hydroids, and gametes are shed either prior to liberation of the medusae or shortly thereafter. The eggs are surrounded by an envelope bearing nematocysts (heterotrichous microbasic euryteles). The cnidome of both hydroid and medusa stages consists of desmonemes and heterotrichous microbasic euryteles. The diagnosis of the genus Bougainvillia is modified to accommodate this new deep-water species.

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Distribution of deep-water corals of the Flemish Cap, Flemish Pass, and the Grand Banks of Newfoundland (Northwest Atlantic Ocean): interaction with fishing activities

ICES Journal of Marine Science ◽

10.1093/icesjms/fsq071 ◽

2010 ◽

Vol 68 (2) ◽

pp. 319-332 ◽

Cited By ~ 48

Author(s):

F. J. Murillo ◽

P. Durán Muñoz ◽

A. Altuna ◽

A. Serrano

Keyword(s):

Atlantic Ocean ◽

Continental Slope ◽

Deep Water ◽

Coral Species ◽

Habitat Mapping ◽

Bottom Trawl ◽

Soft Corals ◽

Northwest Atlantic ◽

Grand Banks ◽

Black Corals

Abstract Murillo, F. J., Durán Muñoz, P., Altuna, A., and Serrano, A. 2011. Distribution of deep-water corals of the Flemish Cap, Flemish Pass, and the Grand Banks of Newfoundland (Northwest Atlantic Ocean): interaction with fishing activities. – ICES Journal of Marine Science, 68: 319–332. The distribution of deep-water corals of the Flemish Cap, Flemish Pass, and the Grand Banks of Newfoundland is described based on bycatch from Spanish/EU bottom trawl groundfish surveys between 40 and 1500 m depth. In all, 37 taxa of deep-water corals were identified in the study area: 21 alcyonaceans (including the gorgonians), 11 pennatulaceans, 2 solitary scleractinians, and 3 antipatharians. The greatest diversity of coral species was on the Flemish Cap. Corals were most abundant along the continental slope, between 600 and 1300 m depth. Soft corals (alcyonaceans), sea fans (gorgonians), and black corals (antipatharians) were most common on bedrock or gravel, whereas sea pens (pennatulaceans) and cup corals (solitary scleractinians) were found primarily on mud. The biomass of deep-water corals in the bycatches was highest in previously lightly trawled or untrawled areas, and generally low in the regularly fished grounds. The information derived from bottom-trawl bycatch records is not sufficient to map vulnerable marine ecosystems (VMEs) accurately, but pending more detailed habitat mapping, it provides a valuable indication of the presence/absence of VMEs that can be used to propose the candidate areas for bottom fishery closures or other conservation measures.

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