Contrasting environmental responses in an Atlantic coastal system: Recent sedimentary record from the inner Ría of Vigo (NW Spain)

Abstract

Anthropogenic pressures compromise the integrity of coastal systems, including the Ría of Vigo (NW Spain). Environmental reconstructions often focus on a sedimentary compartment, potentially overlooking their inherent complexities. Here, recent intertidal and subtidal sedimentary records from the inner Ría of Vigo were examined through a multi-proxy perspective, comprising micropaleontological (benthic foraminifera and diatoms), sedimentological (grain-size), organic (TOC, TN and TS) and inorganic-geochemical (Al, Cu, Pb, Zn and Ni), physical (magnetic susceptibility), and stable (δ¹³C and δ¹⁵N) and radiogenic isotope (²¹⁰Pb, ¹³⁷Cs and ^239+240Pu) proxies. The results evidence disruptions during last decades leading to contrasting responses. Intertidal compartments showed accelerated foraminiferal taphonomic loss, which obscured ecological gradients; however, diatoms and geochemistry provided insights into the mosaic of environmental factors. Subtidal bottoms experienced disturbances since the mid-20^th century, impacting benthic foraminifera and diatoms due to mussel aquaculture, urban development and hydrological changes. These processes led to hypertrophic zones with opportunistic foraminifera, benthic and higher salinity diatoms, and higher TOC, TN and δ¹⁵N. The perturbation of previous conditions affected different trophic levels and masked the intrusion of more saline waters and upwelling signals, likely facilitated by the low hydrodynamics and limited water renewal.