Prof Toomas Tammaru, University of Tartu
Arvo Tuvikene, Estonian University of Life Sciences
Prof Lars Förlin, PhD, Göteborg University
The objectives of my thesis were to examine the effects of oil pollution and oil-shale contaminated sedimentson fish biomarkers, and to examine the effect of dispersed environmental contamination in fish in the coastal Baltic Sea. Furthermore, two new biomarkers (flounder's liver colour and toxicant metabolites in fish urine) of pollution are proposed, and the effects of hypoxia on fish biomarkers were studied. Two approaches were used, a laboratory experiment and field sampling. Assessing the effects of oil-spill and disperse environmental contamination of the coastal Baltic Sea included a total of six sampling locations close to heavy shipping routes as well as pristine sea areas. As the study subjects, three fish species were chosen for biomarker analyses: eelpout (Zoarces viviparus) and flounder (Platichthys flesus trachurus) for assessment of the Baltic Sea, and gibel carp (Carassius auratus gibelio) as an experimental model species.
The thesis demonstrates alterations at all studied biological levels in fish from the Baltic Sea, representing biomarkers from genes to fish size parameters. In almost every biomarker comparison, Nõva and Sõrve were the sites that seemed most affected by environmental contaminants. The aquatic pollution of the Nõva oil-spill area was monitored by measuring the content of selected polycyclic aromatic hydrocarbons (PAH) in flounder. The PAH content of livers decreased significantly during 9 months period; there was also a remarkable decrease in PAH metabolite concentrations in bile and urine. Our experimental study demonstrates that the bioavailability of sediment-bound contaminants changes continually and the effects on aquatic organisms depend on physiological state (season, hibernation), aquatic chemistry (dissolved oxygen) and biotic interactions (food availability, biodegradation).
The knowledge gained in this thesis could be useful from the perspective of biomarker monitoring and environmental health assessment.