Spatial distribution of benthic foraminifera in the Palar estuary, Tamil Nadu

Spatial variability of estuarine benthic foraminiferal assemblages in the surface (0–1cm) sediments has been determined for the Palar river estuary, Tamil Nadu. Twelve bottom water and sediment grab samples were collected at different water depths in the estuarine zone to determine the ecological relationship of benthic foraminiferal assemblages with physicochemical characteristics. The water analyses revealed that hypo saline, high dissolved oxygen and low pH conditions were prevailing at water-substrate interface at the time of sampling. The study indicated that salinity, pH and substrate have a patchy linear relationship with living and total faunal frequency but individual species Ammonia beccarii, A. tepida and A. parkinsoniana showed positive linear correlation with salinity and dissolved oxygen values. The restricted connectivity of the estuary with Bay of Bengal and frequent anthropogenic activity appeared to have an adverse effect on the faunal abundance, diversity and spatial distribution. The Q mode cluster analysis based on single linkage approach was performed to determine if any groups of samples or species correlated with ambient environmental factors. The study identified a total of 36 benthic foraminifer species belonging to 3 sub-orders. The faunal assemblages were dominated by two species Ammonia parkinsoniana and A.beccarii nearly at all the sampling stations.