Invasive species an ongoing risk tied to Great Lakes maritime transport

Great Lakes maritime transport brings in thousands of tons of crucial materials for infrastructure projects, but massive freighters also carry a threat to the health of the waterway. 

The risk stems from ballast water – or extra freshwater or ocean water – used to offset the weight from the upwards of 70,000 tons per trip iron ore, limestone and other aggregates. The water is often discharged into waterways at ports to provide stability – a practice that comes with the potential for ushering in damaging invasive species, according to the Canadian nonprofit organization Clear Seas. 

Dr. Jeffrey Ram, a physiology professor at Wayne State University’s School of Medicine, said the vessels are regulated to ensure they carry enough ballast to go deeper in the water when they take on cargo.