Does radiation impact growth of an Australian tropical marine algae? Informing potential risks from offshore oil and gas infrastructure.

As offshore oil and gas facilities near the end of their operational lifespans, they must undergo decommissioning. While Australian legislation mandates the complete removal of decommissioned facilities, there is discussion around the potential benefits of leaving infrastructure, including production pipelines, in place. Decommissioned infrastructure can function as artificial reefs, and recent studies have demonstrated an increase in biodiversity within these novel ecosystems1. However, the impacts of potential contaminants such as naturally occurring radioactive materials (NORM) on marine organisms remain unclear. Scale formation on the internal surfaces of subsea pipelines can contain radionuclides such as radium-226 and radium-228, which may remain within pipelines beyond the production life2. This study aims to understand the potential impact of ionising radiation contained within offshore oil and gas pipelines on marine organisms. The Australian marine microalgae Tisochrysis lutea was exposed to a Ceasium-137 radiation source in environmentally relevant dose rates over a standard 72-hour test period, and algal growth rates were measured daily via flow cytometry. These findings contribute to the development of a risk assessment framework for the management of NORM wastes during offshore infrastructure decommissioning, addressing critical environmental considerations in the oil and gas industry.