Reconstructing the 'environmental DNA' of the former industrial area of Naples 'Baia di Bagnoli-Coroglio' starting from 1830, to understand how quickly the communities of marine organisms have changed in response to environmental deterioration.
This is one of the main results of a study published in the journal Environment International, the result of a collaboration between various Italian and foreign research groups (Stazione Zoologica Anton Dohrn, ENEA, University of Geneva, University of Salento, University of Urbino, Polytechnic University of Marche, University of Fribourg, Polish Academy of Sciences).
The researchers took a sediment core in the Bagnoli-Coroglio Bay, a former industrial area of the Neapolitan municipality that extends over a surface of about 249 hectares on land and 1.453 hectares at sea, they dated the various layers, determining the concentration of pollutants and studying the traces of DNA of marine organisms. These molecules, in fact, survive for hundreds of years 'trapped' in the sediments that accumulate on the seabed year after year.
The DNA extracted from the environment – in our case from the sediments – is called 'environmental DNA' and represents a sort of 'barcode', different from species to species, which allows for their identification.
It was therefore possible to obtain a list of marine organisms present in the sediment starting from the oldest/deepest layers of the core (1830) up to the present. In the first half of the 1800th century, agricultural lands overlooked the Bagnoli-Coroglio Bay, while Posidonia oceanica and a great diversity of organisms thrived on the seabed.
The gradual deterioration of environmental quality from the first decade of the 1900th century, when the first industries were established, up to the period of maximum expansion in the years 1950-1980 with the Ilva/Italsider steelworks, was accompanied by significant changes in the biological community. The disappearance of Posidonia was sudden; the composition of both unicellular organisms living in water and those living in the sediment changed drastically; their diversity decreased and the species probably able to resist high concentrations of hydrocarbons and heavy metals increased.
The sea is home to a great diversity of organisms, from bacteria to microscopic plankton suspended in the water, from algae and marine plants attached to the substrate to the myriad of organisms, large and small, that live on the seabed. However, human activities are threatening the balance of marine environments, especially that of densely populated coastal marine areas, often home to industrial activities.
The discharge of various types of pollutants into the sea seriously damages marine organisms by reducing their diversity: only some species, in fact, manage to survive in polluted waters or sediments. Now, thanks to this international study, it is possible to see not only the current situation but also understand what the environment was like in the past and how quickly the communities of marine organisms have changed in response to environmental deterioration. This study is part of the ABBaCo project, funded by the MUR and coordinated by the Stazione Zoologica Anton Dohrn, aimed at studying the Bagnoli-Coroglio Bay west of the city of Naples.
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