The influence of industrial metal pollution on Foraminifera in the Gulf of Naples (Bagnoli)

Chemical pollutants, such as heavy metals, are a major threat to marine ecology and biodiversity in the Mediterranean Sea. The Gulf of Naples plays a crucial role in risk assessment and mitigation of waste contamination in the area, as severe anthropogenic pressure originates from local urban and industrial areas and intense maritime traffic. The now defunct ILVA steel plant in Bagnoli, constructed between 1905 and 1910, was a leading contributor of metal pollution in the Gulf of Naples until its shutdown in 1990. In order to evaluate the potentially long-lasting impact of this industrial activity on local foraminiferal communities, as well as the response of individual benthic foraminifera, multiple geochemical and sedimentological analytical techniques were employed and the results compared to a non-impacted reference area; inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) revealed exceptionally high levels of metals in the sediment samples taken in close proximity to the former steel plant. Faunal analysis via stereo microscopy and scanning electron microscopy (SEM) concluded slightly lower biodiversity indices and a lower abundance of living foraminifera in the polluted sample, and the near absence of the otherwise ubiquitous genus Ammonia in the reference area. Energy-dispersive X-ray spectroscopy (EDX) was utilized to determine concentrations of iron within foraminiferal tests and established that all analyzed specimens from the polluted sampling site had elevated quantities of iron in their tests, compared to individuals from the reference sampling site. Based on the findings of this investigation, the metal pollution emitted by the former steel mill is still impacting foraminiferal assemblages and individuals to this day. However, the complex interactions of anthropogenic toxins, benthic microorganisms and the environment are not fully unraveled yet and require further analysis.