EVALUATING THE PERFORMANCE OF STRESS INDEX ON BENTHIC FORAMINIFERA IN EASTERN COASTAL MARGIN OF BANGLADESH

The present research is concerned with evaluating the stress index or, in other words, the effect of marine pollution on benthic foraminifera at the eastern coastal margin of Bangladesh. In order to carry out the investigation, the samples were collected from ten locations to evaluate the Foraminifera Stress Index (FSI). The FORAM index (FI) and the foraminifera diversity index (Shannon-Weiner Diversity Index) were computed from these samples. About 250 foraminifera specimens were collected, of which 22 species, 19 genera, and 17 families of predominantly benthic provenance were recognized. Astrorhiza, Elphidium, Robulus, and Eponoides are the region’s four most abundant genera in order of relative abundance and frequency of occurrence.

Based on the relative abundance, the investigated foraminifera was also grouped into functional groups of Opportunistic (54.31%), Heterotrophic (27.99%), and Symbiont bearing (17.66%). The percentage of stress-tolerant opportunistic genera was found to be highest due to the high level of contamination. The stress-tolerant and heterotrophic genera (Quinqueloculina, Elphidium, Ammonia, Trochammina) dominated the sensitive or symbiont genera (Calcarina, Operculina, Cibicides, Nummulites).

The average FSI value is 1.27, which indicates a polluted environmental condition. The average FI score is 1.83, which indicates stressful circumstances unfavorable for reef development. For the investigation of the Foraminiferal shell, in addition to statistical computing.

From the EDAX analysis, it has been found that oxygen (O) with a weight range of (36.51-53.71%) and calcium (Ca) with a weight range of (30.44-53.38%) are the primary components of the foraminifera test. The shell of the foraminifera has been found to include trace elements such as magnesium (Mg), iron (Fe), aluminum (Al), manganese (Mn), and gold (Au).

According to the findings, the coast is likely experiencing moderate levels of ecological stress. These characteristics of the shell signatures demonstrate that benthic foraminiferous products can react to anthropogenic pollution and that they could be used as possible proxies for the marine environment.