Marine mussel, Mytilus galloprovincialis. (Photo: Andrew Butko/CC BY-SA 3.0)

Marine warming could strengthen radiation-induced genotoxicity in mussels

New research exploring the impact of rising temperatures coupled with the presence of tritium on marine mussels (Mytilus galloprovincialis) concluded that increased sea temperatures could dramatically enhance and accelerate radiation-induced DNA effects in marine invertebrates.

The study, led by Plymouth University in conjunction with the Centre for Environment, Fisheries and Aquaculture Science (Cefas), demonstrated that at radiation dose rates considerably below the recommended international guidelines, induced DNA strand breaks appeared earlier at higher temperature compared to lower temperature.

The research revealed that at 15 ºC, DNA damage was only significantly elevated after seven days in contrast to 25 °C where a similar response was observed after three days.

Scientists involved say this suggests an acceleration of radiation-induced DNA damage and potentially compromising defence mechanisms as indicated by changes in expression profiles of genes involved in heat-shock protection, cell cycle progression and repair of DNA breaks.

Temperature is an abiotic factor of particular concern for assessing the potential impacts of radionuclides, many of them having very long half-lives, on marine species, and with sea surface temperatures forecast to rise 0.5-3.5˚C in the next 30-100 years, determining the interaction of radiological exposure has never been more important.

“Compared to other radionuclides, large amounts of tritium are discharged, mostly as water, in the marine environment by nuclear power plants (NPPs) and nuclear fuel reprocessing plants (NFRPs),” pointed out Awadhesh Jha, Professor of Genetic Toxicology and Ecotoxicology.

Professor Jha also explained that cooling water from nuclear installations is one of the major sources of tritium in the aquatic environment and that as thermal discharges from nuclear facilities is an important environmental issue, second only to the release of radionuclides which could extend for a long distance from the discharge point, such studies are important in determining the hazard and risk to the natural biota and therefore environmental sustainability.

“These results are important as they allow us to better understand the risks a warming ocean poses to marine life. We already know climate change is impacting things such as fish physiology, reproduction and migration, but this research is part of a growing body of evidence that is suggesting rises in sea water temperature may increase the risk posed by certain chemical and physical pollutants,” stressed Brett Lyons, from the Environment and Animal Heath group based in Cefas’ Weymouth laboratory.

For the study, published in the Journal of Environmental Radioactivity, the mussels were exposed to tritiated water (HTO) with differing temperatures of 15˚C and 25˚C, and DNA damage and gene expressions were determined along with accumulation of tritium in different tissues of the mussels over a period of seven days.
 
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