Characterisation of mesoscale features and phytoplankton variability in the Mozambique Channel

Lamont, Tarron; Barlow, Ray; Morris, Tamaryn; Berg, M.A. van den

doi:10.1016/j.dsr2.2013.10.019

Cited by 37 publications

(33 citation statements)

References 46 publications

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“…S2; Wiggert et al 2006), which could also be the reason for increased Ba concentration. Equally, classic eddy upwelling occurs throughout the Mozambique Channel, enhancing chlorophyll-a concentrations in the centre of the cyclones (Lamont et al 2014). Magnesium concentrations decreased linearly with time after hatch.…”

Section: Discussionmentioning

confidence: 93%

Otolith microchemistry: a useful tool for investigating stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean

Artetxe-Arrate

Fraile

Crook

et al. 2019

Mar. Freshwater Res.

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A better understanding of the stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean is needed to ensure the sustainable management of the fishery. In this study, carbon and oxygen stable isotopes (δ13C and δ18O) and trace elements (138Ba, 55Mn, 25Mg and 88Sr) were measured in otoliths of young-of-the-year (YOY) and age-1 yellowfin tuna collected from the Mozambique Channel and north-west Indian Ocean regions. Elemental profiles showed variation in Ba, Mg and Mn in YOY otolith composition, but only Mn profiles differed between regions. Differences in YOY near-core chemistry were used for natal-origin investigation. Ba, Mg and Mn were sufficiently different to discriminate individuals from the two regions, in contrast with carbon and oxygen stable isotopes. A linear discriminant analysis resulted in 80% correct classification of yellowfin tuna to their natal origin. Classification success increased to 91% using a random forest algorithm. Finally, a unique larval source was detected among age-1 yellowfin tuna. The signal of these fish resembled that of YOY from a north-west Indian Ocean origin, highlighting the importance of local production. The present study supports the use of otolith chemistry as a promising approach to analyse yellowfin stock structure in the Indian Ocean.

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Section: Discussionmentioning

confidence: 93%

Otolith microchemistry: a useful tool for investigating stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean

Artetxe-Arrate

Fraile

Crook

et al. 2019

Mar. Freshwater Res.

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“…The dynamics associated with mesoscale eddies have a significant influence on biological communities [12][13][14]. An in situ investigation of the MB eddy one month after its formation showed a uniform distribution of chlorophyll a in the upper 100 m [16], as a result of the well mixed nature of the water column under strong wind conditions [15,16].…”

Section: Discussionmentioning

confidence: 99%

“…An increase in diadinoxanthin:chlorophyll a ratios and a decline in the quantum efficiency of It has been demonstrated that eddies in the southwest Indian Ocean have a significant influence on the structure of biological communities and on ecosystem functioning. Overall, it is typical to have elevated chlorophyll in cyclonic eddies, and lower concentrations in anticyclonic eddies [12][13][14]. However, there appear to be some differences in the characteristics of cyclonic eddies sampled during different seasons in the MC and MB.…”

Section: Introductionmentioning

confidence: 92%

“…In the MC to the north, in situ investigations revealed that cyclonic eddies had distinct subsurface chlorophyll maxima (SCMs) associated with shallow upper mixed layers and nitracline depths and deep euphotic zones during austral spring and summer [15], where prokaryotes (picophytoplankton) generally dominated at the surface and flagellates (nanophytoplankton) at the SCM [13,14]. The MB eddy was different in that it was sampled during austral winter, had a shallower euphotic zone, a deeper upper mixed layer and a uniform chlorophyll distribution throughout the euphotic zone [15,16].…”

Section: Discussionmentioning

confidence: 99%

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Variations in Remotely-Sensed Phytoplankton Size Structure of a Cyclonic Eddy in the Southwest Indian Ocean

2018

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Phytoplankton size classes were derived from weekly-averaged MODIS Aqua chlorophyll a data over the southwest Indian Ocean in order to assess changes in surface phytoplankton community structure within a cyclonic eddy as it propagated across the Mozambique Basin in 2013. Satellite altimetry was used to identify and track the southwesterly movement of the eddy from its origin off Madagascar in mid-June until mid-October, when it eventually merged with the Agulhas Current along the east coast of South Africa. Nano-and picophytoplankton comprised most of the community in the early phase of the eddy development in June, but nanophytoplankton then dominated in austral winter (July and August). Microphytoplankton was entrained into the eddy by horizontal advection from the southern Madagascar shelf, increasing the proportion of microphytoplankton to 23% when the chlorophyll a levels reached a peak of 0.36 mg·m −3 in the third week of July. Chlorophyll a levels declined to <0.2 mg·m −3 in austral spring (September and October) as the eddy propagated further to the southwest. Picophytoplankton dominated the community during the spring period, accounting for >50% of the population. As far as is known, this is the first study to investigate temporal changes in chlorophyll a and community structure in a cyclonic eddy propagating across an ocean basin in the southwest Indian Ocean.

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“…McGillicuddy et al, 1998;Martin and Richards, 2001;Mackas et al, 2005;Kolasinski et al, 2012). Eddies also transport nutrients, salt and other chemicals (Bakun, 2006;Xiu et al, 2011), thereby regulating marine species abundances and community composition (Owen, 1981;Sabarros et al, 2009;Huggett, 2013;Lamont et al, 2013). Cyclonic eddies rotate clockwise in the Southern Hemisphere and carry a cold water core, corresponding to a reduced sea surface height.…”

Section: Introductionmentioning

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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Characterisation of mesoscale features and phytoplankton variability in the Mozambique Channel

Cited by 37 publications

References 46 publications

Otolith microchemistry: a useful tool for investigating stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean

Otolith microchemistry: a useful tool for investigating stock structure of yellowfin tuna (Thunnus albacares) in the Indian Ocean

Variations in Remotely-Sensed Phytoplankton Size Structure of a Cyclonic Eddy in the Southwest Indian Ocean

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

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