Onset of the Indian Ocean isotopic signature in the Philippine Sea Plate: Hf and Pb isotope evidence from Early Cretaceous terranes

Yellowfin tuna of the Indian Ocean is overfished, and a better understanding of the stock structure is needed to enable sustainable management. Here, otolith δ18O values of young-of-the-year fish from known nursery areas of the equatorial Indian Ocean (West, Central and East) were used to establish a reference isotopic signature to predict the origin of sub-adult and adult individuals. Sub-adult tuna otolith δ18O values from Reunion Island were similar to the West nursery signature, but otolith δ18O values of sub-adults from Pakistan were unlike any of the nurseries sampled. Therefore, δ18O values from the Pakistan area samples were considered an additional nursery source for predicting the origin of adult tuna, using a multinomial logistic regression classification method. The western equatorial area was the most productive nursery for three fishing grounds sampled, with a minor contribution of Pakistan-like origin fish. Contribution of Central or East nurseries to the adult population was negligible. One adult otolith was analysed by secondary ion mass spectrometry along the otolith growth transect and results were compared with an isoscape approach to infer lifetime movements. This study is an important first step towards understanding the spatial structure and connectivity of the species.

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The Indian Ocean-type isotopic signature in western Pacific marginal basins: Origin and significance

Active Margins and Marginal Basins of the Western Pacific - Geophysical Monograph Series ◽

10.1029/gm088p0175 ◽

1995 ◽

pp. 175-197 ◽

Cited By ~ 63

Author(s):

Rosemary Hickey-Vargas ◽

Janet M. Hergt ◽

Piera Spadea

Keyword(s):

Indian Ocean ◽

Isotopic Signature ◽

Western Pacific ◽

The Indian Ocean

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Superplume mantle tracked isotopically the length of Africa from the Indian Ocean to the Red Sea

Nature Communications ◽

10.1038/s41467-019-13181-7 ◽

2019 ◽

Vol 10 (1) ◽

Cited By ~ 2

Author(s):

John M. O’Connor ◽

Wilfried Jokat ◽

Marcel Regelous ◽

Klaudia F. Kuiper ◽

Daniel P. Miggins ◽

...

Keyword(s):

Indian Ocean ◽

Red Sea ◽

Isotopic Signature ◽

Rift System ◽

Seismic Velocities ◽

East African Rift System ◽

East African ◽

The Indian Ocean ◽

Complex Scenario ◽

Chemical Anomaly

AbstractSeismological findings show a complex scenario of plume upwellings from a deep thermo-chemical anomaly (superplume) beneath the East African Rift System (EARS). It is unclear if these geophysical observations represent a true picture of the superplume and its influence on magmatism along the EARS. Thus, it is essential to find a geochemical tracer to establish where upwellings are connected to the deep-seated thermo-chemical anomaly. Here we identify a unique non-volatile superplume isotopic signature (‘C’) in the youngest (after 10 Ma) phase of widespread EARS rift-related magmatism where it extends into the Indian Ocean and the Red Sea. This is the first sound evidence that the superplume influences the EARS far from the low seismic velocities in the magma-rich northern half. Our finding shows for the first time that superplume mantle exists beneath the rift the length of Africa from the Red Sea to the Indian Ocean offshore southern Mozambique.

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