DNA double strand breaks and chemical elements in incubating female common eiders (Somateria mollissima) in Christiansø, Denmark.

Abstract

Genotoxic agents are ubiquitous in the Baltic Sea and may cause effects not only at a molecular level but at an individual and population level as well. Fasting during reproduction may lead to a state of oxidative stress and enhance the genotoxicity of nonessential elements due to low levels of essential elements and nutrients. Therefore genotoxic agents pose a threat to fasting species. The present study aimed to assess DNA double strand breaks (DNA DSBs) in relation to body mass and non-essential elements in blood of female common eiders (Somateria mollissima) in the Southern Baltic Sea (Christiansø, Denmark) at the beginning (day 5) and end (day 25) of incubation. Furthermore, the present study aimed to investigate the relationships between nonessential and essential elements in whole blood of female common eiders (Somateria mollissima) on day 5 and day 25 of incubation. This was a unique study because each incubating eider was sampled twice and therefore acted as its own control. The present study analyzed DNA DSBs using gel electrophoresis to quantify DNA-fraction, of total DNA, that migrated into the gel (DNA-FTM). During incubation DNA-FTM increased significantly throughout incubation (0.4 - 70 %). Body mass decreased significantly (17 - 44 %) throughout incubation. Significantly increasing levels of Cd were associated with decreasing levels of Ca and Zn and increasing levels of Cu, which may demonstrate an increase in absorption of Cd from day 5 to day 25 of incubation. While significantly increasing levels of Pb were significantly correlated with decreasing levels of Ca, which may indicate Pb was released from medullary bone during incubation. As and Hg were not found to significantly increase. Hg was found to be positively and significantly correlated with Se, suggesting a protective effect of Se on Hg. DNA-FTM was found to be negatively and significantly correlated to body mass and positively correlated to Hg (not significantly). Given the high levels of DNA DSBs in the current study compared to previous studies in Baltic Sea eiders, there may be other factors at play, apart from non-essential elements, causing DNA DSBs. However, the high levels ofDNA DSBs and body mass loss may reflect the overall health of this endangered population, which is exposed to multiple stressors.