Distribution of certain ecological parameters and foraminiferal distribution in the depositional environment of Palk Strait, east coast of India

Out of 102 species, only 36 species are living ones. The total distribution of foraminifera is higher at Devipattinam and Attankarai followed by Mandapam, Thondi and Kodiyakkarai whereas at Kottaipattinam, Manalmelkudi and Sethubavachattiram it is noticed to be in the lower order. Organic matter and living species show positive relation. The lack of relationship between dead species and the organic matter has suggested that the dead species recorded in the sediments must have been primarily drifted/transported as empty calcareous shells. From the sand/silt/clay ratios, it is inferred that the sediments are normally sandy in nature but silty sand dominates at deeper depths. Carbonate content establishes a weak negative correlation with all parameters except organic matter and dead species. Fluctuation of salinity values in Attankarai indicates the influx of fresh water from Vaigai river. Based upon the ecological parameters the stations have been grouped into different environments. Among them, bar environment registers low species diversity than the other three. The following species are appreciably distributed in different stations namely Ammonia beccarii, Elphidium crispum, Rosalina globularis, Asterorotalia trispinosa, Osangularia venusta and Pararotalia nipponica. This strait is influenced by an unique environment of high order of siltation leading to the depletion of living forams. The present study highlights the abundance of living species in places of high organic matter. The ongoing process of active siltation is manifested in the bar environment and the same is reflected in the low organic matter and less species diversity.