Analysis of Abundance and Origin Possibility of Planktonic Foraminifera in Sulawesi Sea

Abstract

Abstract Foraminifera is very diverse and adaptive, both in its morphology and biology. It is a potential bioindicator to understand the ecological and physical conditions of the ancient and modern waters based on their distribution. It has been well confirmed that the abundance of foraminifera (as a fossil) in sediment can reflect the ocean conditions above (mixed layer to upper ocean) where it was deposited. Planktonic foraminifera however can be considered as passive particles, their movement is carried by ocean currents. In consequence, the foraminifera abundance may represent more wider ocean condition according to the ocean current pattern. This study aims to examine the role of ocean currents in the distribution of foraminifera in the Sulawesi Sea. Ten gravity core sediment samples from 73-3009 m water depth were retrieved by RV Geomarin III from the Marine Geological Institute, Indonesia. We conducted quantitative analysis, including calculation of abundance and cluster analysis. Two decades (1992-2012) of ocean current simulated data from the Hybrid Coordinate Ocean Model (HYCOM) is used in this analysis, extending from 115°E-140°E and 8°N-2°S. The result indicates that planktonic foraminifera is abundant in the Sulawesi Sea by 86.3%. There were several predominant planktonic species such as Globigerinoides ruber (22.6%), Globigerina bulloides (15.3%), and Neoglobuquadrina dutertrei (10.1%). The ocean current above the sample location is constantly moving eastward as a part of the NECC. The average currents velocity shows that foraminifera in sample site S-03 with depth 2064 m may originated from up to 1035 kilometers away from its recent location.