Researchers at the Australian Institute of Marine Science in Townsville have found that corals exposed to the highest concentrations of coal dust die within two weeks.
The scientific study mimicked the exposure of marine species to coal dust by adding carefully controlled amounts of fine coal particles and measuring the responses over time.
The study was undertaken to assess the risk of shipping coal through a tropical marine environment, as previous studies had only been undertaken in temperate marine environments.
The international trade of coal is highly dependent on transportation by sea. As coal shipments are increasing on a global scale, recent scientific, political and public opinion had raised concerns regarding coal mining and shipment next to tropical coastal environments, including World Heritage listed sites such as the Great Barrier Reef (GBR).
Concerns have generally centered around increased dredging for port access of coal vessels, and the burning of coal which increases greenhouse gas emissions. However, growth in the seaborne coal trade has been accompanied by increased shipping accidents, which have the potential to cause widespread damage to marine ecosystems.
The GBR was lucky to survive damage in 2010 when 68,000 tons of coal on board the grounded Shen Neng spilled onto the GBR. Calm conditions helped to minimize damage.
The study found that in most cases the impacts increased with the level of coal concentration and length of time of exposure. Although the study did not specifically investigate the stress-response pathways, it was clear that coal particles affect corals, fish and seagrass in ways that are similar to the effects of other suspended solids, including: light limitation, direct smothering and reduced feeding efficiency. Despite these similarities, coal particles appear to have more severe effects on corals than other suspended solids.
The findings from the study by scientists from the Australian Institute of Marine Science (AIMS) and ARC Centre of Excellence for Coral Reef Studies have been published in Nature Scientific Reports. The report can be found here.