Industrial pressures and flooding events: shaping the benthic foraminiferal community in the Crotone basin (Ionian Sea) over the last century

Since coastal marine ecosystems have been increasingly affected by human activities over the past century, different marine legislations (e.g., Water Framework Directive) have been enacted to assess the environmental quality and its deviation from the background conditions. This study provides evidence of the historical environmental and Ecological Quality Status (EcoQS) changes along the 35-cm long sediment KR3 core, 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, influenced by intense industrial activity (i.e., zinc purification, phosphorus production) between 1920s and 1990s. Geochemical, sedimentological, and benthic foraminiferal temporal changes along the core were investigated to reconstruct environmental and EcoQS variations. Trace metals concentrations (i.e., Cr, Pb, Zn) and Pollution Load Index values increase particularly during 1948–1968 period, reflecting the main industrial phase. The CONISS analysis based on benthic foraminiferal assemblages identifies three main phases: industrial settlement (1926–1959), industrialization peak and initial production decline (1962–1990), and industrial decline (1994–2016), that well correspond to the exploitation in the Crotone coastal area. Exp(H’bc) and Foram-AMBI reflect moderate environmental conditions since 1926, and poor conditions between 1962 and 1968 corresponding to the main industrialization peak. Input of sandy fraction associated to historical documented flooding events corresponds to pronounced peaks of diversity (e.g., 1996 event) and the occurrence of shallower species along the core. This study highlights the necessity of an integrated (geochemical and biological) approach to separate the signals of anthropogenic pressure, extreme natural events, and shipping transport in the complex EcoQS assessment of submarine canyons.