Stratigraphical distribution of diatom assemblages in the Semarang Mangrove Area, Indonesia

¹ Department of Environmental Science, School of Postgraduate Studies, Diponegoro University, Semarang, Indonesia
² Department of Oceanography, Faculty of Fisheries and Marine Sciences, Diponegoro University Semarang, Indonesia
³ School of Postgraduate Studies, Diponegoro University, Indonesia
⁴ Department Biology, Science and Mathematics Faculty, Diponegoro University, Semarang, Indonesia
⁵ Cluster for Paleolimnology (CPalim), Diponegoro University, Semarang, Indonesia.

^* Corresponding author: This email address is being protected from spambots. You need JavaScript enabled to view it.

Abstract

The goal of this study was to explore the possible use of sediment diatoms as indicator of environmental change in the Tambakredjo Semaarang. Diatom samples were collected from corer in the Mangrove area representing both subtidal and intertidal habitats. A total of 25 diatom taxa were found, dominated by Fallacia 27.7%, Cyclotella at around 22.7%, and Tryblinonella 9.0%. Based on the diversity index, the highest diversity index is layer 15 and 0 cm H' = 2.33 the lowest diversity index is at layer 30 cm H'=0.5. Based on cluster and stratigraphy analysis the zonation of the diatom is divided into four zones. Zone IV (35-25 cm), Zone III (20 cm), Zone II (10-15 cm) and Zone I (0-5 cm). Layer 25-35 cm mostly abundance with marine species, layer 20 cm above reflected condition with slightly brackish water. But the trend of freshwater species has resumed above 5 cm towards. Domination of planktonic species indicated that the water level increased during a period. Based on diatom reconstruction the patterns of changing abundance by the groups of marine and freshwater species suggest that there has been an increase in salinity in this area over time. Salinity gradient in the study area was a major factor influencing the composition of diatom assemblages.