| Secondary Calcification of Planktic Foraminifera from the Indian Sector of Southern Ocean |
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| 作者姓名： | Rahul MOHAN Suhas S. SHETYE Manish TIWARI Narayanpillai ANILKUMAR |
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| 作者单位： | 1 National Centre for Antarctic and Ocean Research, Headland Sada, Goa –403 804, India
2 National Institute of Oceanography, Dona Paula, Goa-403 004, India |
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| 基金项目： | We are indebted to the Secretary, the Ministry of Earth Sciences for the support in our endeavor to undertake comprehensive studies of the Southern Ocean. We also would like to thank the Director, NCAOR. We are grateful to the Chief Scientist, scientific personnel and the crew of Pilot Expedition to Southern Ocean. This is NCAOR contribution no. 41/2014. |
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| 摘 要： | This study focused on planktic foraminifera in plankton tows and surface sediments from the western Indian sector of Southern Ocean in order to evaluate the potential foraminiferal secondary calcification and/or dissolution in the sediment. It is found that the symbiotic foraminiferal species are abundant in the subtropical region, whereas non-symbiotic species dominate in the sub-Antarctic and polar frontal regions. The distribution of the symbiotic and non-symbiotic foraminiferal species is controlled by temperature, salinity, light, nutrients and phytoplankton biomass. There is also a lateral southern extent in abundance of planktic foraminifera from surface sediments to plankton tows. The shell weights of the planktic foraminifera N. pachyderma, G. bulloides and G. ruber within the surface sediments are on an average heavier by 27%, 34% and 40% respectively than shells of the same size within the plankton tows, indicative of secondary calcification. The planktic foraminiferal isotopes show the presence of heavier isotopes in the surface sediment foraminifera as compared to plankton tows, thus confirming secondary calcification. Secondary calcification in G. ruber occurs in the euphotic zone, whereas in case of N. pachyderma and G. bulloides it is at deeper depths. We also observed a decrease in the shell spines in surface sediment foraminifera as compared to plankton tows, indicative of the morphological changes that foraminifera underwent during gametogenesis.
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| 关 键 词： | Southern Ocean foraminifera climate change stable isotopes shell weight |
| 收稿时间： | 2/8/2014 12:00:00 AM |
| 修稿时间： | 2014/9/16 0:00:00 |
Secondary Calcification of Planktic Foraminifera from the Indian Sector of Southern Ocean |
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| Authors: | Rahul MOHAN Suhas S SHETYE Manish TIWARI and Narayanpillai ANILKUMAR |
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| Institution: | 1. National Centre for Antarctic and Ocean Research, Headland Sada, Goa-403 804, India
2. National Centre for Antarctic and Ocean Research, Headland Sada, Goa-403 804, India;National Institute of Oceanography, Dona Paula, Goa-403 004, India |
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| Abstract: | This study focused on planktic foraminifera in plankton tows and surface sediments from the western Indian sector of Southern Ocean in order to evaluate the potential foraminiferal secondary calcification and/or dissolution in the sediment. It is found that the symbiotic foraminiferal species are abundant in the subtropical region, whereas non-symbiotic species dominate in the sub-Antarctic and polar frontal regions. The distribution of the symbiotic and non-symbiotic foraminiferal species is controlled by temperature, salinity, light, nutrients and phytoplankton biomass. There is also a lateral southern extent in abundance of planktic foraminifera from surface sediments to plankton tows. The shell weights of the planktic foraminifera N. pachyderma, G. bulloides and G. ruber within the surface sediments are on an average heavier by 27%, 34% and 40% respectively than shells of the same size within the plankton tows, indicative of secondary calcification. The planktic foraminiferal isotopes show the presence of heavier isotopes in the surface sediment foraminifera as compared to plankton tows, thus confirming secondary calcification. Secondary calcification in G. ruber occurs in the euphotic zone, whereas in case of N. pachyderma and G. bulloides it is at deeper depths. We also observed a decrease in the shell spines in surface sediment foraminifera as compared to plankton tows, indicative of the morphological changes that foraminifera underwent during gametogenesis. |
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| Keywords: | Southern Ocean foraminifera climate change stable isotopes shell weight |
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