Distribution of Planktonic Foraminifera in the Recent Subtropical Water Mass and their Comparison to the Surface Sediment: Implications for Palaeoenvironmental Reconstruction

Article type: Research Article

Authors: Mohiuddin, Mia Mohammad

Affiliations: Department of Geology and Mining University of Rajshahi, Rajshahi 6205, Bangladesh

Note: [] Corresponding author. E-mail: [email protected]

Abstract: A comparison between planktonic foraminifera assemblage in the sediment trap and those at core-tops located close to mooring in the subtropical Pacific was analyzed to assess the relationship between preserved faunal assemblages and the recent fluxes. At Station WCT-1, the total foraminiferal fluxes showed a seasonal variation, characterized by high flux value during summer and low in winter. The seasonal patterns for the two trap depths also showed a close similarity in both the number and magnitude of the peaks. Variation in the foraminiferal fluxes could be representing seasonality in the production of different foraminiferal species and reflect change in hydrographic conditions in the upper water column. Dissolution susceptible species, G. ruber, G. glutinata, G. quadrilobatus and G. sacculifer are abundant in surface water and dominated in the flux material. On the other hand, dissolution resistant species, G. inflata, N. pachyderma and G. crassaformis, increased their relative abundance in the surface sediment. The foraminiferal species differ between the trap and core-top assemblages and indicate that the sediments have been significantly altered since deposition. The comparisons between foraminiferal core-top assemblages from this region can therefore be directly related to modern sea-surface conditions, providing an analogue for interpreting past environmental change from fossil assemblages.

Keywords: Planktonic foraminifera, sediment trap, surface sediment, subtropical pacific, palaeoenvironment

Journal: Asian Journal of Water, Environment and Pollution, vol. 3, no. 1, pp. 95-102, 2006