Modern Benthic Foraminifera In Subtidal Waters Of Johor

Abstract

Far-field regions are locations away from major glaciation centres and can provide the best possible estimates on eustatic sea-level changes. As a far-field region of stable Sundaland, Malaysia is an ideal location for studying and predicting Holocene sea-level changes. However, modern analogues for such investigations are limited for many far-fields, including Malaysia. We examined the ecological distributions of modern subtidal benthic foraminifera on the east coast of Johor, Peninsular Malaysia. The faunal composition of surface sediment samples (279 species) was dominated by calcareous-hyaline taxa (74.4 ± 10.2%), followed by agglutinated (13.5±7.6%) and calcareous-porcelaneous (12.1 ±5.2%) taxa, with the co-dominance of Asterorotalia pulchella (synonym: Asterorotalia tripinosa), Discorbinella bertheloti, Pseudorotalia indopacifica, Ammonia sp.l and Cavarotalia annectens. Canonical Correspondence Analysis indicated that both water depth and sediment texture influenced the distributions of subtidal benthic foraminifera. Agglutinated species such as Textularia pseudosolita, T. aggliitinans, Bigenerina nodosaria and T. foliácea were found in middle-shelf environments (depth >20 m), while calcareous genera such as Elphidium, Pararotalia and Ammonia were found in the inner-shelf (depth <20 m). Although the Weighted Averaging regression transfer function based on depth revealed modest performance of foraminifera (r2jaCk=0.40) (for which the other factors such as salinity and wave transport could be responsible), the distributions of subtidal foraminifera are clearly associated with water depth. At Johor, currently observed shifts in subtidal foraminiferal species with depth, which are linked to existing sediment types, can serve as base-line data for sea-level reconstruction on the east coast of Peninsular Malaysia.