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The relative impact of the combined stresses hypoxia and ionising radiation in the marine bivalve, Mytilus edulis
Stockholm University, Faculty of Science, Department of Systems Ecology. (Marine Ecotoxicology)
(English)Manuscript (preprint) (Other academic)
Abstract [en]

A key requirement to accurate risk assessment of the impact of radioactive materials in the environment is the ability to assess the interactions and combined effects of other existing stresses or contaminants. Hypoxia is a common and growing hazard in the world’s oceans. Hypoxia is known to cause radioresistance in tumorous tissues of patients undergoing radiotherapy, however the impacts of radiation on marine organisms exposed to hypoxia is largely untested. The hypoxia tolerant bivalve – the blue mussel, Mytilus edulis - was exposed to a range of doses of gamma radiation (0.04Gy – 4Gy), following acclimatisation to either normoxia (10mgoxygen.l-1) or moderate hypoxia (3mgoxygen.l-1). Oxidative stress (lipid peroxidation) and antioxidant enzyme (catalase and superoxide dismutase) analyses were performed on tissues taken from these mussels. Very little or no effects were observed resulting from irradiation regardless of oxic treatment, however large increases in oxidative stress and antioxidant response were observed in the tissues of mussels acclimatised to hypoxia. The results suggest that the mussels are more impacted by the moderate level of hypoxia than the high doses of radiation, indicating that the endpoints or the species is not sensitive to irradiation and that historical exposure has led to adapted responses to hypoxia.

National Category
Biological Sciences
URN: urn:nbn:se:su:diva-83401OAI: diva2:575576
Available from: 2012-12-10 Created: 2012-12-10 Last updated: 2012-12-11Bibliographically approved
In thesis
1. Exploring phenomena that affect the fate and impact of radioactive materials in the blue mussel
Open this publication in new window or tab >>Exploring phenomena that affect the fate and impact of radioactive materials in the blue mussel
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Current protection of the marine environment from radiation is based largely on measuring, estimating and modelling accumulation and impact(s) of radionuclides in a few marine species. Using a relevant marine organism, this thesis focusses on investigating some poorly described phenomena that could cause deviations from predicted measurements.

Paper I investigated the biological transformation of tritium (radioactive hydrogen) into an organic compound. The resulting organically bound tritium (OBT) showed increased accumulation in mussels, unique incorporation into a key biological molecule (DNA), extended persistence in tissues, and greater toxicity than the inorganic form. Paper II demonstrated significant disparity in OBT accumulation between functionally similar microalgae species and that OBT in algae is readily transferred to a consumer.

Highly radioactive particles are a complex issue in radioecology due to their concentrated dose geometry, potentially inducing very different impacts in organisms, compared to external irradiation. Paper III developed a method to introduce radioactive particles that would facilitate their recovery, improve dose-calculation, and aid the measurement of toxicological endpoints. It also showed that such particles can be incorporated into mussel tissues, causing significant effects.

In Paper IV, hypoxia – another major ecological hazard in the marine environment – was expected to reduce radiosensitivity. The minimal observable effect from radiation prevented identification of such an interaction, and indicates drawbacks in the (otherwise sensitive) endpoints used. It appears that stressors like hypoxia may be more of a health hazard to marine organisms than environmental levels of ionising radiation.

By understanding such causes of variation in accumulation and impact, it is possible to improve risk assessment, providing more justification for regulations chosen and minimising conservatism in setting environmental standards.

Place, publisher, year, edition, pages
Stockholm: Department of Ecology, Environment and Plant Sciences, Stockholm University, 2013. 93 p.
Radioecology, ionising radiation, environmental protection, Mytilus edulis, bioaccumulation, dose-response, ecotoxicology, tritium, particle, hypoxia
National Category
Biological Systematics
Research subject
Marine Ecotoxicology
urn:nbn:se:su:diva-83404 (URN)978-91-7447-616-3 (ISBN)
Public defence
2013-01-18, DeGeersalen, Geovetenskapens hus, Svante Arrhenius väg 14, Stockholm, 13:00 (English)

At the time of doctoral defense, the following papers were not published and had a status as follows: Paper 3: Manuscript. Paper 4: Manuscript.

Available from: 2012-12-27 Created: 2012-12-10 Last updated: 2013-01-02Bibliographically approved

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Jaeschke, Benedict
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