Assessment of genetic risk in fishes inhabiting zones of dumped chemical munitions in the Baltic Sea

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In the Baltic Sea, there are exclusive zones—the Bornholm zone, the Gotland Deep and the Little Belt Sea—where many thousand tonnes of chemical munitions (CM) were dumped after the Second World War. The goal of the study is to assess environmental genotoxicity levels in different fish species inhabiting dumped CM sites with the aim of outlining genetic risk levels, integrating stress and fish population health. Genotoxicity biomarker responses, such as the formation of micronuclei (cytogenetic and DNA damage), nuclear buds (DNA damage), binucleated cells with nucleoplasmic bridges (radionuclide effects), binucleated, 8‐shaped cells (alterations in chromosome segregation and cytokinesis), or fragmented apoptotic cells (elimination of cytogenetic damage), were analysed in blood erythrocytes of flounder, dab, plaice, turbot, herring, and Atlantic cod. Multifactorial analysis of genotoxicity biomarker responses was applied in relation to fish condition and other bioparameters, such as fish age, length, sex, body and liver weight, stomach fullness, and population origin. The main findings of the work were a significant increase of genotoxicity in 2009–2010, compared to 2001–2004, in fish from the Bornholm Basin (up to 57‐times) and the Little Belt (up to 17‐times) CM dumping sites. GIS mapping of 2009–2010 data showed the highest level of genetic risk (responses over threshold level in 80–100% of specimens) in herring and flounder from 14 sampling stations in the Bornholm Basin and at station B01, located closely to the CM dumping site in the Little Belt. The ecological significance of genetic damage, characterized as a long‐term irreversible process, is discussed in relation to the genetic risk for wildlife populations.