Using biomarkers in assessment of environmental contamination in fish – new perspectives
Date
2014-03-26
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Abstract
Doktoritöö eesmärk oli hinnata naftareostuse, põlevkivitööstuse poolt reostatud setete ja Läänemere rannikuvetes leiduva hajureostuse mõju kalade biomarkeritele. Lisaks eelnevale pakub töö välja kaks uut biomarkerit (lesta maksa värvus ning toksiliste ainete metaboliitide sisaldused uriinis) ning uurib hapnikupuudust olulise füsioloogilisi protsesse mõjutava lisafaktorina. Töös on kasutatud kahte metoodilist lähenemist: nii eksperimendi käigus saadud andmeid kui ka välitöödel kogutud materjali. Läänemere rannikuvetest koguti proove kokku kuues piirkonnas ning biomarkereid analüüsiti kolmel kalaliigil: emakalal (Zoarces viviparus), lestal (Platichthys flesus trachurus) ja hõbekogrel (Carassius auratus gibelio).
Biomarkerite analüüside käigus leiti kaladel mitmeid kahjustusi alates geneetilistest kõrvalekalletest kuni muutusteni üldises konditsioonis ja kasvukiiruses. Erinevate Eesti rannikumere proovipunktide võrdluses joonistusid selgelt välja Nõva ja Sõrve uurimisalad, kus elavatel kaladel leiti kõige rohkem keskkonnareostusest tulenevaid kahjustusi. 2006. aastal toimunud Nõva naftareostuse järelmõjude uuringus analüüsisiti naftaproduktide kontsentratsioone ning biomarkereid reostusala lesta kudedes. Tulemustest lähtub, et isegi 5 kuud pärast naftareostust sisaldavad kalade koed arvestataval määral toksilisi aineid, kuid juba 9 kuud pärast reostust on toimunud oluline kontsentratsioonide langus. Lisaks kontsentratsioonidele sõltub toksilise aine mõju ka füsioloogilistest protsessidest. Läbi viidud laborieksperiment näitab, et ka mitmed keskkonnamõjurid (hapnikusisaldus, toidu kättesaadavus) ning kalade füsioloogiline seisund (sigimisaeg, hiberneerumine) mõjutavad toksiliste ainete kehasse sisenemist ning mõjude avaldumist.
Käesoleva doktoritöö tulemusel saadud uute teadmiste kasutuspõld on lai, alates üksikute biomarkerite hindamisest seire kontekstis ja lõpetades üleüldise keskkonnaseisundi hindamise strateegiate kujundamisega.
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.
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.
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Keywords
kalad (zool.), biomarkerid, veereostus, Eesti, Pisces, biomarkers, hydrosphere pollution, Estonia