Holocene benthic foraminifera in two marine lakes in Misool, Raja Ampat (Indonesia)

Abstract

Marine lakes have been proposed as a unique ecosystem to assess the physical, chemical and biological interaction within a marine community. However, study on the dynamics of past community composition and biodiversity in marine lakes is still limited. Benthic foraminifera have been considered as important environmental indicators. This study investigated the diversity and distribution of foraminiferal assemblages from two marine lake sediment cores (MIS-01 and MIS-17) in Misool, Raja Ampat. A total of 6693 benthic foraminiferal specimens, which belong to 34 species were recorded from 36 samples from both cores of the marine lakes. The species were characterized by a low diversity and dominated by hyaline perforated species of Ammonia sp, Brizalina semicarinata, Bolivina striatula, and Bolivina sp Four agglutinated species include Ammobaculites sp, Caronia exilis, Reophax irregularis, Textularia agglutinans and porcelanous imperforated species consist of Fissurina bispinata, Lagena sp, Quinqueloculina carinatastriata, Quinqueloculina sp and Quinqueloculina exsculpta. Downcore variation of the species indicates six major break along the cores which correlates to the six main cluster of the sample with a distinguish depth boundary. Comparison of the assemblages and species diversity shows that the foraminifera from Misool are similar to the ones from Palau. Assessment of individual species and assemblage environmental preferences suggest that oxygen level and salinity might have been the driving factors behind the changes in community assemblages. In comparison to the other community, the temporal partitioning along the cores fits with those based on the mollusk community, particularly at 200 cm depth where diversity was higher than the upper layer.