Benthic Foraminifera as Pollution Biomarkers: A Morphological Approach

Coastal areas are often intervened by anthropic activities, which increase the contamination of toxic agents such as heavy metals. This causes adverse morphological effects on benthic microorganisms, such as foraminifera. This group is one of the most susceptible to environmental deterioration, so they can be used as pollution biomarkers by identifying shell abnormalities. Therefore, 28 sediment samples from northern Chile were analyzed, calculating the Abnormality Index-FAI and its spatio-temporal distributions in benthic foraminifera. As well as the minimum and maximum abnormality percentages and their relationship with heavy metals concentrations, using a generalized non-linear model and a principal component analysis. The results indicated a proportion of abnormal shells within the ranges described for polluted areas conditions, revealing environmental stress conditions. This reflected a change in the environmental conditions in the most recent sediments of the bay. The highest FAI values were observed to the southwest of the bay, caused by the local current system. The species Bolivina seminuda , Buliminella elegantissima , and Epistominella exigua presented a greater number of deformities, allowing them to be used as contamination biomarkers. A significant correlation was found between Ti, Mn, Ni, Va, and Ba with decreased chamber sizes, wrong coiling, scars, and number of abnormality types. This suggests the effect of the particular geochemical conditions of the area on the heavy metals that cause toxic effects on foraminifera. These analyses are an efficient tool for identifying the effects of environmental stress before they occur in higher organisms, mitigating the environmental impact on marine biodiversity.