Distribution of Benthic Foraminifera off Kelantan, Peninsular Malaysia, South China Sea

Abstract

We investigated the distribution of modern benthic foraminifera from Kelantan waters in the western part of the Sunda Shelf, South China Sea. Twenty-nine benthic foraminiferal species were identified from seven samples collected along a ∼250 km-long transect perpendicular to the Kelantan coastline. Calcareous hyaline species made up 57% of the overall assemblages collected in the study area, followed by calcareous porcelaneous (23%) and agglutinated (20%) species. Cluster analysis recognised two distinctive groups. Group A represented the shallow inner-shelf area (19–35 m water depth) with a coarse sand-dominated substrate where Amphistegina papillosa (13.37%) and Assilina ammonoides (11.04%) were highly abundant. Group A had lowest diversity with no agglutinated species. Group B, occurred at 40–60 m water depth, had higher foraminiferal diversity and was characterised by a very fine sand substrate. The foraminiferal assemblages here were dominated by calcareous hyaline species in group B followed by calcareous porcelaneous and agglutinated species. Group B was characterised by Assilina ammoinodes (11.04%), Heterolepa dutemplei (10.29%), and Discorbinella bertheloti (10.03%). The dominant agglutinated species in Group B were Textularia agglutinans (4.93%) and Cylindroclavulina bradyi (3.55%). Shallow-water species, such as Amphistegina spp., were absent from Group B. Our study shows that the distribution of benthic foraminiferal assemblages from the western Sunda shelf off Kelantan, is closely associated with changes in seafloor sediment, distance from the shore, and water depth.

The Occurrence and Distribution of Benthic Foraminifera in Tropical Waters Along the Strait of Malacca

“…Moreover, the distribution of D. bertheloti was observed at 50-60 m water depth at relative abundances of >15%. A similar finding was reported by Azmi et al (2020) in the southern region of the South China Sea, where D. bertheloti represented 20% of the foraminiferal assemblages at ~56 m depth. We, therefore, confirm that this species represents depths of 50-60 m in sandy tropical waters.…”

“…To avoid using reworked specimens, only foraminiferal taxa with a relative abundance of >2% in atleast one sample were used to determine the foraminiferal zonation and fauna-environment relationship. The Q-mode hierarchical cluster analysis based on the Euclidean distance similarity measure was used to understand the biozonation of foraminiferal assemblages (Mello and Buzas, 1968;Culver et al, 2012;Azmi et al, 2020). Multivariate canonical correspondence analysis (CCA) was calculated using XLSTAT software to determine the influence of environmental variables, water depth, and sediment characteristics on foraminiferal assemblages.…”

Early-to-mid Holocene environmental change in the Kallang River Basin, Singapore

“…At deeper water depths (water depth >60 m) offshore Kuala Terengganu, Assilina ammonoides and Heterolepa dutemplei dominated sites with shellrich sand substrates . Similarly, Assilina ammonoides (11.04%) and Heterolepa dutemplei (10.29%) also dominate foraminiferal assemblages at water depth between 40 and 60m off the Kelantan coastline (Azmi et al, 2020). These larger foraminifera taxa were not found at similar depth range between 20 and 60 m off the Ayeyarwady delta, where smaller rotaliids such as Asterorotalia pulchella and Ammonia sp.…”

“…Studies that investigate the foraminiferal distribution in coral reefs are not included (e.g., Förderer et al, 2018;Junita et al, 2020;A'ziz et al, 2020Natsir et al, 2022). Foraminiferal distribution of study areas in the Peninsula Malaysia (marked in yellow) are summarised in Table 5.2.…”

“…Foraminiferal distribution of study areas in the Peninsula Malaysia (marked in yellow) are summarised in Table 5.2. The foraminiferal distribution on the Sunda Shelf is largely related to environmental variables that can be associated with water depth such as grain-size distribution, salinity, organic carbon content and primary productivity (e.g., Azmi et al, 2020;Suriadi et al, 2019;. Table 5.2 summarises the foraminiferal assemblages recognised in several studies in the Peninsular Malaysia and dominant species of these assemblages.…”