Abstract
In sediment cores spanning ~500 years of history in the Gulf of Trieste, down-core changes in molluscan community structure are characterized by marked shifts in species and functional composition. Between the 16th and 19th century, a strong heavy metal contamination of the sediments, most notably by Hg, together with the effects of natural climatic oscillations (increased sedimentation and organic enrichment) drive community changes. Since the early 20th century up to 2013, the combined impacts of cultural eutrophication, frequent hypoxic events and intensifying bottom trawling replace heavy metal contamination and climatic factors as the main drivers. The pollution-tolerant and opportunistic bivalve Corbula gibba and the scavenging gastropod Nassarius pygmaeus significantly increase in abundance during the 20th century, while species more sensitive to disturbances and hypoxia such as Turritella communis and Kurtiella bidentata become rare or absent. An infaunal life habit and scavenging emerge as the dominant life strategies during the late 20th century. Down-core shifts in the proportional abundances of molluscan species and functional groups represent a sensitive proxy for past ecological changes and reveal a century-long anthropogenic impact as the main driver behind these processes in the northern Adriatic Sea, offering also a unique perspective for other shallow marine ecosystems worldwide.
Highlights
Most marine ecosystems worldwide are affected by human activities, and pristine coastal areas have virtually disappeared [1,2,3]
The Bay of Panzano has a unique history of heavy metal contamination driven by the mercury mine of Idrija in the Slovenian hinterland, which was active from the late 15th century until a few decades ago [10, 11]
The shallow northern Adriatic Sea originated at the onset of the Holocene when the rising sea level gradually covered the vast alluvial plains that had been exposed since the Wurmian glaciation (18,000–23,000 BC) [30]
Summary
Most marine ecosystems worldwide are affected by human activities, and pristine coastal areas have virtually disappeared [1,2,3]. The northern Adriatic Sea is ideal for this type of investigation due to its long history of human interactions with the marine environment and comparatively long written historical documentation. The coasts of this shallow epicontinental sea have been densely urbanised since historical times, and the many rivers discharging into the basin—above all the Po River —enrich it with nutrients and pollutants [1, 7]. The Bay of Panzano has a unique history of heavy metal contamination driven by the mercury mine of Idrija in the Slovenian hinterland, which was active from the late 15th century until a few decades ago [10, 11]
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