On the circulation of water masses across the Mascarene Plateau in the South Indian Ocean

New, Adrian L.; Alderson, S.G.; Smeed, David A.; Stansfield, K.

doi:10.1016/j.dsr.2006.08.016

Cited by 46 publications

(62 citation statements)

References 36 publications

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“…During southwest monsoon (June-August), the core of SEC shifts further south (south of 10S) and surface waters in SCTR are contributed mainly by the meridional flow of high-saline waters from the Arabian Sea 6 . Previous studies also suggest that SSS variability in SCTR is mainly regulated by the ocean surface currents 14,24,32 . Figure 6 a and b shows the depth-time plots of salinity averaged over WSCTR and ESCTR.…”

Section: Methodsmentioning

confidence: 97%

“…Figure 6 a and b shows the depth-time plots of salinity averaged over WSCTR and ESCTR. It can be seen that except during July-September, the SCTR is capped by low-saline (<35.2) tropical surface water 32 over the highsaline (>35.25) subsurface water. Further, WSCTR is ~0.3 units more saline than ESCTR.…”

Section: Methodsmentioning

confidence: 99%

“…The observed high amplitude of chl a variability in WSCTR during June-September could not be explained by the MLD variability alone. Waters around Chagos archipelago (~5S, ~72E) and Mascarene plateau (4-20S, ~56E) are always characterized by elevated chl a in SCTR 10,32,38 . Some areas of elevated chl a in SCTR are related to ridges and islands (stars in Figure 2, GEBCO Atlas 2003).…”

Section: Methodsmentioning

confidence: 99%

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Seasonal Surface Chlorophyll a Variability in the Seychelles–Chagos Thermocline Ridge

George¹,

Murukesh²,

Anilkumar³

et al. 2018

Current Science

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Seychelles-Chagos Thermocline Ridge (SCTR, 5-10S, 50-75E) in the southwestern tropical IndianOcean is a unique area that experiences year-round upwelling. This is a response to the upward Ekman pumping prevalent in the region. Satellite data, model data and objectively analysed Argo temperature/ salinity data have been used to study the seasonal surface chlorophyll a (chl a) variability in SCTR. Variability of surface chl a concentration in SCTR showed a weak semiannual signature. The western part of SCTR (WSCTR, 50-62E) is characterized by higher chl a concentration than the eastern part (ESCTR, 63-75E). Average chl a concentration in WSCTR/ESCTR showed a primary peak in JulyAugust (~0.26/~0.16 mg/m 3 ) and a secondary peak in January (~0.14/~0.12 mg/m 3 ). Minimum chl a concentration (~0.12/~0.1 mg/m 3 ) was observed during MarchApril and December-January. The high amplitude of chl a variability observed during July-August is associated with weak stratification and deep mixed layer depth (MLD). Deep MLD reaching to nutrient-rich thermocline entrains nutrients to the surface and thereby increases the surface chl a concentration. However, the low surface chl a concentration is a result of shallow MLD in the region. The deep MLD (30-40 m) observed during June-October is dominated by wind mixing and supported by buoyancy mixing. Shallow MLD (<30 m) observed during rest of the year is due to weak wind mixing and high surface buoyancy. The high surface buoyancy is a manifestation of ocean surface warming and presence of low saline surface waters in the SCTR region.

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Section: Methodsmentioning

confidence: 97%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Seasonal Surface Chlorophyll a Variability in the Seychelles–Chagos Thermocline Ridge

George¹,

Murukesh²,

Anilkumar³

et al. 2018

Current Science

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“…The shoaling of isopycnals across the SEC also allows the deeper nutrients of the south Indian Ocean to migrate to shallower depths (New et al 2005). In addition, the presence of the Mascarene Plateau leads to enhanced vertical mixing (New et al 2007). Added to all this is the seasonal movement of the shallow thermocline in response to the WSC changes alluded to previously.…”

Section: Methodsmentioning

confidence: 99%

Effects of annual changes in primary productivity and ocean indices on breeding performance of tropical roseate terns in the western Indian Ocean

Monticelli¹,

Ramos²,

Quartly³

2007

Mar. Ecol. Prog. Ser.

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We assessed the influence of inter-annual changes in primary productivity and local, regional and large scale ocean indices on the breeding parameters of roseate terns Sterna dougallii on Aride Island, Seychelles, western Indian Ocean. Productivity (chicks per breeding pair), timing of breeding and clutch and egg sizes were monitored annually for 8 yr and correlated with local ocean productivity (denoted by Sea-viewing Wide Field-of-view Sensor, SeaWiFS, estimates of chlorophyll concentration, CC), sea surface temperature and indices recording the status of the Indian Ocean Dipole and of El Niño. The rate of increase in CC between mean laying date and CC peak value was positively related to roseate tern productivity and mean clutch size over the 1998 to 2005 study period. Colony productivity seemed also to be influenced by the Multivariate El Niño Index. In most years, the breeding phenology of roseate terns corresponded to the local increase in CC around Aride, and failure to adjust timing of reproduction to the timing of the phytopankton bloom decreased the probability of breeding success. This is the first study showing that a tropical seabird species is sensitive to inter-annual variations in the intensity and timing of the phytoplankton bloom, which should be connected to annual variations in the availability of its main fish prey (juvenile goatfishes). Overall, these patterns indicate that the reproduction of this top marine predator is dictated by the temporal variability in oceanographic conditions. We suggest that CC data available over the world's oceans may be a useful tool to develop models predicting the fate of colonies of inshore feeding seabirds when other, more conventional, monitoring methods cannot be used.

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“…New et al, 2007). Close to the western margin, where the SEC bifurcates, warm surface waters are transported poleward, either east of Madagascar, or through the Mozambique Channel (e.g.…”

Section: Oceanographic Settingmentioning

confidence: 99%

Anti-cyclonic eddy imprint on calcite geochemistry of several planktonic foraminiferal species in the Mozambique Channel

Steinhardt

Cléroux

Ullgren³

et al. 2014

Marine Micropaleontology

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Hydrographic conditions in the Mozambique Channel are dominated by the passing of large anticyclonic eddies, propagating poleward into the upstream Agulhas area. Further south, these eddies have been found to control the shedding of Agulhas rings into the Atlantic ocean, thereby playing a key role in Indo-Atlantic Ocean exchange. The element composition of several planktonic foraminifera species collected from sediment trap samples, was compared to in situ water column data from the Mozambique Channel. Single-chamber trace element composition of these foraminifera reveals a close coupling with hydrographic changes induced by anticyclonic eddies.Obtained Mg/Ca values for the surface dwelling Globigerinoides ruber as well as the thermocline dwelling Neogloboquadrina dutertrei follow temperature changes and reduced temperature stratification during eddy conditions. At greater depth, Globorotalia scitula and Pulleniatina obliquiloculata record stable temperatures and thus respond to hydrographic changes with a deepening in habitat depth. Furthermore, test Mn/Ca values indicate a close relationship between water column oxygenation and Mn incorporation in these planktonic foraminiferal species.

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On the circulation of water masses across the Mascarene Plateau in the South Indian Ocean

Cited by 46 publications

References 36 publications

Seasonal Surface Chlorophyll a Variability in the Seychelles–Chagos Thermocline Ridge

Seasonal Surface Chlorophyll a Variability in the Seychelles–Chagos Thermocline Ridge

Effects of annual changes in primary productivity and ocean indices on breeding performance of tropical roseate terns in the western Indian Ocean

Anti-cyclonic eddy imprint on calcite geochemistry of several planktonic foraminiferal species in the Mozambique Channel

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