The Interdependency of the Morphological Variations of the Planktonic Foraminiferal Species Globigerina bulloides in Surface Sediments on the Environmental Parameters of the Southwestern Indian Ocean.

Abhijit Mazumder,Neloy Khare,Pawan Govil

doi:10.1155/2014/621479

Abstract

18 surface sediment samples collected from a north-south transect along the Indian Ocean have been analyzed for planktonic Foraminifera content. Among the other planktonic foraminiferal faunas, Globigerina bulloides was present substantially in all samples. Census data of G. bulloides were measured for different parameters (average size, mean proloculus size, coiling direction, and number of chambers) and a Q-mode cluster analysis was applied on these data. Samples were segregated into two homogeneous clusters, each reflecting particular environmental conditions. Two clusters are as follows: (1) Cluster A, comprised of 6 samples and characterized by the highest range of foraminiferal and ecological parameters, except sea surface temperature and salinity which shows the lowest range, and (2) Cluster B, comprised of 12 samples and characterized by the lowest range of foraminiferal parameters and ecological parameters, except sea surface temperature and salinity which shows the highest range. The study suggests that the ecological parameters are the governing factors for the morphological characteristics of planktonic foraminiferal species G. bulloides.

Highlights

Morphological variations of planktic Foraminifera have been extensively used to decipher paleoclimatic, paleoenvironmental, and paleoecological reconstructions [1,2,3].Globigerina bulloides d’Orbigny, a spinose planktic foraminifer, is substantially present in temperate to subpolar water masses and is characteristic of upwelling areas in lower latitudes [4,5,6,7,8,9,10,11]
Earlier workers [18,19,20,21] discussed the general distribution of G. bulloides in Indian Ocean surface waters and sediments along with its relation to the change of ecological parameters, no attempt was made to study the morphological variations of this planktic foraminiferal species along a north-south transect in the Indian Ocean region in connection with the ecological parameters
The nitrate content ranges from 1.165 μmol to 7.81 μmol with an average of 4.14 μmol, while the phosphate content shows a range of 1.774 μmol to 8.423 μmol with an average of 4.07 μmol, and total nutrients show a range of 4.202 μmol to 11.547 μmol with an average of 8.21 μmol

Summary

Introduction

Globigerina bulloides d’Orbigny, a spinose planktic foraminifer, is substantially present in temperate to subpolar water masses and is characteristic of upwelling areas in lower latitudes [4,5,6,7,8,9,10,11]. In these upwelling regions, G. bulloides contributes maximum foraminiferal flux to the ocean floor [12, 13] and provides important geochemical information for paleoceanographic studies [14,15,16,17]. The major objective of this study is to link the patterns of morphological variation with the changes in physicochemical properties of the surface water in order to comprehend the ecological control on morphological characteristics in G. bulloides in the modern marine environment

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Conclusion