A STUDY OF MICROHABITAT OF INTERTIDAL FORAMINIFERA FROM CHANDIPUR COAST, ODISHA

摘要

This study serves as a first investigation report of benthic foraminifera from Chandipur, east coast of the Indian subcontinent. It concerns the microhabitats of the intertidal living foraminiferal population of Chandipur coast. Three short core samples of 20 cm each were collected from various sub-environments of the Chandipur coast (mud flat, estuary mouth and intertidal flat) and investigated for benthic foraminifera. Eleven genera of foraminifera have been identified, consisting both calcareous and agglutinated forms. The calcareous foraminifera are comprised of Ammonia spp., Haynesina spp., Asterorotalia sp. and Quinqueloculina sp.; with minor occasional occurences of Cribroelphidium sp. and the agglutinated species are Trochammina spp., Miliammina sp. and Haplophragmoides sp. The living foraminiferal count reduces drastically down the cores and shows one or more maxima deeper in the sediment. These different types of vertical distribution are reflections of the tolerance or preference levels of taxa with respect to one or more abiotic parameters. Food availability and dissolved oxygen might play a role in determining the lower downcore maxima. Bioturbation can also actively transport foraminifera to deeper sediment layers, and cause accidental occurrence of taxa that are usually found at the sediment surface. The living population consisted mainly of Haynesina germanica, Haynesina depressula and Ammonia tepida. Abundance of living populations of Haynesina spp. suggests a fluvial influence and higher clay percentages of this area. This also corroborates with good abundance of Ammonia tepida, indicating fluvial influence and lower percentages of sand. Good abundance of Asterorotalia trispinosa indicates high sedimentation rates.