The palaeoenvironmental and paleo-ecological quality status changes in the Crotone basin (Calabria, Ionian Sea, Italy): insights from benthic foraminifera

Costal marine ecosystems have been severely affected by human activities in the last century and different marine legislations (e.g., MSDF, WFD) have been enacted to assess the environmental quality and its deviation from the background conditions. This study investigates the paleoenvironmental changes along the 35-cm long sediment core, namely KR3, retrieved at the head of the Esaro submarine canyon in the Crotone basin (Calabria, Ionian Sea, Italy). Crotone is part of the Crotone-Cassano- Cerchiara Site of National Interest, historically influenced by intense industrial activity (i.e., zinc purification, phosphorus production) between 1920s and 1990s. This study aims to examine the geochemical, sedimentological and benthic foraminiferal variations along the core to infer the paleoenvironmental changes and the variation of the Paleo-Ecological Quality Status (Paleo-EcoQS). Trace metals concentrations increased particularly after the 1920s with a peak between 1940 and 1962, reflecting the industrial settlement. Contamination levels decreased after 1980s due to industrial activity cessation. The ecological indices (e.g., FSI, expH’bc, Foram-AMBI) reveal a deterioration of the Paleo-EcoQS in the central part of the core (i.e., ~1940-1990) that well matches with the industrialization peak and the Pollution Load Index. Moreover, peaks of diversity well correspond to input of sandy fraction associated with the flooding events reported in the historical archives. The hierarchical cluster analysis based on benthic foraminiferal assemblages resulted in the identification of three main phases: initial industrialization (~1920-1950), industrialization peak (~1950-1990) and initial recovery (~1990-2020) that perfectly correspond to the development and exploitation of the Crotone area.