Indian‐Atlantic interocean exchange: Dynamics, estimation and impact

Ruijter, W. P. M. de; Biastoch, Arne; Drijfhout, Sybren; Lütjeharms, J. R. E.; Matano, Ricardo P.; Pichevin, Thierry; Leeuwen, Peter Jan van; Weijer, Wilbert

doi:10.1029/1998jc900099

Cited by 331 publications

(301 citation statements)

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“…We explored the possibility that recent dispersal by currents between the Atlantic and Indo-Paci® c could explain our ® ndings. Although this tropical species is highly unlikely to be able to disperse around Cape Horn (South America) due to the cold waters of the circum-Antarctic current, dispersal around the Cape of Good Hope (South Africa) may be more probable, as warm waters of the Agulhas current travelling south along the eastern side of South Africa are able tō ow into the southeastern Atlantic (Briggs 1974;Gordon 1985;de Ruijter et al 1999). However, the Benguela cold current, and upwelling off southwestern Africa, present a major barrier to the dispersal of even highly vagile tropical Indian Ocean taxa into the Atlantic (Bowen et al 2001).…”

Section: Discussionmentioning

confidence: 99%

Evidence of a human–mediated invasion of the tropical western Atlantic by the ‘world's most common brittlestar’

Roy

Sponer

2002

Proc. R. Soc. Lond. B

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Approximately three million years ago the Isthmus of Panama formed an impenetrable land barrier between the tropical eastern Paci® c Ocean and the tropical western Atlantic Ocean. Since this time, isolated geminate species have evolved from once contiguous populations, either side of the barrier. One such organism whose distribution is divided by the Isthmus is the tropical brittlestar Ophiactis savignyi, once suggested to be the most common brittlestar in the world. Rather than showing a genetic pattern consistent with a history of isolation, we show that this species has recently dispersed between the Paci® c Ocean and the western Atlantic Ocean. This conclusion is based upon a phylogenetic analysis using sequences of the COI mitochondrial DNA gene from these populations. Identical haplotypes between oceans, and a genetic signature of population expansion, provide compelling evidence that the western Atlantic contains at least one cluster of haplotypes recently derived from the Indo-Paci® c. Inadvertent human-aided translocation of individuals, presumably in ballast water or fouling communities, is strongly implicated as a mechanism for dispersal between oceans. We believe that cryptic marine invasions are likely to be common and our awareness of them will rapidly increase as systematic and phylogeographic knowledge of marine taxa grow.

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Section: Discussionmentioning

confidence: 99%

Evidence of a human–mediated invasion of the tropical western Atlantic by the ‘world's most common brittlestar’

Roy

Sponer

2002

Proc. R. Soc. Lond. B

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“…The upper limb of the Atlantic MOC originates in the southeastern Atlantic where South Atlantic Current (SAC) water merges with Indian Ocean leakage in the Benguela Current (Reid, 1989;Peterson and Stramma, 1991;Stramma and England, 1999;de Ruijter et al, 1999) Accurate knowledge of the circulation patterns in the southeastern Atlantic and of the amounts of water from different sources in the Benguela Current has remained lacking because of the complexities of the ocean circulation and the sparse amount of suitable direct measurements.…”

Section: Scientific Backgroundmentioning

confidence: 99%

“…Estimates of Agulhas leakage using geostrophic sections range from around 3-15 Sv (1 Sv = 10 6 m 3 /s), and estimates of leakage due to Agulhas rings range from around 3-9 Sv based on the formation of 6 rings per year each with a transport of 0.5 to 1.5 Sv (de Ruijter et al, 1999;Gordon, 2001). Estimates of the amount of intermediate water entering the Benguela Current from the Agulhas range from near zero (Rintoul, 1991) to around 50% (Gordon et al, 1992).…”

Section: Scientific Backgroundmentioning

confidence: 99%

“…Many rings have been measured at sea as described by Dumcombe Rae (1991), Lutjeharms (1996), Arhan et al (1999), de Ruijter et al (1999, Garzoli et al (1999), andMcDonagh et al (1999). Agulhas rings are among the most energetic eddies in the world (Olson and Evans, 1986).…”

Section: Scientific Backgroundmentioning

confidence: 99%

“…Interocean exchange of heat and salt around South Africa is thought to be key in maintaining the global overturning circulation of the ocean (Gordon et al, 1992;Lutjeharms, 1996;de Ruijter et al, 1999;Sloyan and Rintoul, 2001). Indian Ocean leakage into the South Atlantic takes place near the Agulhas Current retroflection where large Agulhas rings (~ 400 km overall diameter) pinch off and translate into the Atlantic.…”

Section: Introductionmentioning

confidence: 99%

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Agulhas leakage into the Atlantic estimated with subsurface floats and surface drifters

Richardson

2007

Deep Sea Research Part I: Oceanographic Research Papers

160

158

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Agulhas ring formation as a barotropic instability of the retroflection

Weijer

Zharkov²,

Nof

et al. 2013

Geophysical Research Letters

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Agulhas Leakage is an important link in the global ocean circulation, as it transfers a significant volume of relatively warm and salty water from the Indian Ocean to the Atlantic Ocean. The main route of this transfer is through the shedding of large Agulhas rings from the Agulhas retroflection. In this paper we study the dynamics of the ring formation process by analyzing the stability of the Indian/Atlantic supergyre in a reduced gravity model. We show that the ring‒shedding process results from a barotropic instability of the steady circulation in the Agulhas retroflection region. The destabilizing mode appears to be linked to a Rossby basin mode of the combined South Indian/Atlantic basin, which is localized in the retroflection region by the background flow.

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Indian‐Atlantic interocean exchange: Dynamics, estimation and impact

Cited by 331 publications

References 135 publications

Evidence of a human–mediated invasion of the tropical western Atlantic by the ‘world's most common brittlestar’

Evidence of a human–mediated invasion of the tropical western Atlantic by the ‘world's most common brittlestar’

Agulhas leakage into the Atlantic estimated with subsurface floats and surface drifters

Agulhas ring formation as a barotropic instability of the retroflection

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