Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea

Annekatrin J. Enge*, Julia Wukovits, Wolfgang Wanek, Margarete Watzka, Ursula F. M. Witte, William R. Hunter, Petra Heinz

*Corresponding author for this work

Research output: Contribution to journalArticle

5 Citations (Scopus)
6 Downloads (Pure)

Abstract

Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with C-13 and N-15) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels.

Original languageEnglish
Article number71
Pages (from-to)1-12
Number of pages12
JournalFrontiers in Microbiology
Volume7
DOIs
Publication statusPublished - 11 Feb 2016

Keywords

  • foraminifera
  • OMZ
  • Arabian Sea
  • carbon
  • nitrogen
  • in situ

Cite this

Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea. / Enge, Annekatrin J.; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula F. M.; Hunter, William R.; Heinz, Petra.

In: Frontiers in Microbiology, Vol. 7, 71, 11.02.2016, p. 1-12.

Research output: Contribution to journalArticle

Enge, Annekatrin J. ; Wukovits, Julia ; Wanek, Wolfgang ; Watzka, Margarete ; Witte, Ursula F. M. ; Hunter, William R. ; Heinz, Petra. / Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea. In: Frontiers in Microbiology. 2016 ; Vol. 7. pp. 1-12.
@article{4576efc4860f4c1cb5859a9dc78781f1,
title = "Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea",
abstract = "Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with C-13 and N-15) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels.",
keywords = "foraminifera, OMZ, Arabian Sea, carbon, nitrogen, in situ",
author = "Enge, {Annekatrin J.} and Julia Wukovits and Wolfgang Wanek and Margarete Watzka and Witte, {Ursula F. M.} and Hunter, {William R.} and Petra Heinz",
note = "Acknowledgments We are very grateful to Hiroshi Kitazato for the possibility to participate in the research cruise “YK08-11.” We thank the captain and crew of the R/V Yokohama and the pilots of the submersible Shinkai 6500 for the skillful performed dives. We are also very thankful to Markus Moeseneder for his help in the sampling phase during the cruise. We would also like to thank the two reviewers for their comments and suggestions. This article was supported by the Open Access Publishing Fund of the University of Vienna.",
year = "2016",
month = "2",
day = "11",
doi = "10.3389/fmicb.2016.00071",
language = "English",
volume = "7",
pages = "1--12",
journal = "Frontiers in Microbiology",
issn = "1664-302X",
publisher = "FRONTIERS MEDIA SA",

}

TY - JOUR

T1 - Carbon and Nitrogen Uptake of Calcareous Benthic Foraminifera along a Depth-Related Oxygen Gradient in the OMZ of the Arabian Sea

AU - Enge, Annekatrin J.

AU - Wukovits, Julia

AU - Wanek, Wolfgang

AU - Watzka, Margarete

AU - Witte, Ursula F. M.

AU - Hunter, William R.

AU - Heinz, Petra

N1 - Acknowledgments We are very grateful to Hiroshi Kitazato for the possibility to participate in the research cruise “YK08-11.” We thank the captain and crew of the R/V Yokohama and the pilots of the submersible Shinkai 6500 for the skillful performed dives. We are also very thankful to Markus Moeseneder for his help in the sampling phase during the cruise. We would also like to thank the two reviewers for their comments and suggestions. This article was supported by the Open Access Publishing Fund of the University of Vienna.

PY - 2016/2/11

Y1 - 2016/2/11

N2 - Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with C-13 and N-15) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels.

AB - Foraminifera are an important faunal element of the benthos in oxygen-depleted settings such as Oxygen Minimum Zones (OMZs) where they can play a relevant role in the processing of phytodetritus. We investigated the uptake of phytodetritus (labeled with C-13 and N-15) by calcareous foraminifera in the 0-1 cm sediment horizon under different oxygen concentrations within the OMZ in the eastern Arabian Sea. The in situ tracer experiments were carried out along a depth transect on the Indian margin over a period of 4 to 10 days. The uptake of phytodetrital carbon within 4 days by all investigated species shows that phytodetritus is a relevant food source for foraminifera in OMZ sediments. The decrease of total carbon uptake from 540 to 1100 m suggests a higher demand for carbon by species in the low oxygen core region of the OMZ or less food competition with macrofauna. Especially Uvigerinids showed high uptake of phytodetrital carbon at the lowest oxygenated site. Variation in the ratio of phytodetrital carbon to nitrogen between species and sites indicates that foraminiferal carbon and nitrogen use can be decoupled and different nutritional demands are found between species. Lower ratio of phytodetrital carbon and nitrogen at 540 m could hint for greater demand or storage of food-based nitrogen, ingestion, or hosting of bacteria under almost anoxic conditions. Shifts in the foraminiferal assemblage structure (controlled by oxygen or food availability) and in the presence of other benthic organisms are likely to account for observed changes in the processing of phytodetritus in the different OMZ habitats. Foraminifera dominate the short-term processing of phytodetritus in the OMZ core but are less important in the lower OMZ boundary region of the Indian margin as biological interactions and species distribution of foraminifera change with depth and oxygen levels.

KW - foraminifera

KW - OMZ

KW - Arabian Sea

KW - carbon

KW - nitrogen

KW - in situ

U2 - 10.3389/fmicb.2016.00071

DO - 10.3389/fmicb.2016.00071

M3 - Article

VL - 7

SP - 1

EP - 12

JO - Frontiers in Microbiology

JF - Frontiers in Microbiology

SN - 1664-302X

M1 - 71

ER -