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.
“So, (when) they pump ballast out – if that ballast came from a foreign port, or even a different port in the Great Lakes that doesn’t have this organism, that water would pump organisms into our Great Lakes,” said Ram, noting zebra mussels and quagga mussels in the Great Lakes “came most likely from being pumped by ballast.”
Zebra mussels and quagga mussels are far from the only invasive species to come into the Great Lakes via ballast water. Approximately 30% of the estimated 185 aquatic non-native species established in the Great Lakes are cited as being introduced by ship ballast water, according to Clear Seas. Ram agreed, saying at least a third of the leaders of invasive species probably come that way, and his past work has focused on pathogens that might come into the Great Lakes. He suspects the next “terrible invader” in the Great Lakes via ballast water would be sea lamprey.
As invasive species have nearly no predators in the Great Lakes, they can multiply quickly, according to the nation’s leading grassroots environmental organization Clean Water Action. These species can then out-compete the native species, disrupt the food chain and degrade the native ecosystems, in addition to potentially threatening human health, harming the fishing, agriculture and tourism industries and impacting existing water infrastructure.
Management of the massive ships are a prime concern for the Lake Carriers’ Association, the oldest trade association in the country, which advocates for US cargo carriers on the Great Lakes, said Eric Peace, the group’s vice president.
Ballast water treatment systems aren’t meant to work in freshwater, Peace said. It’s a matter of figuring out how to put something on the carriers traveling in the Great Lakes that does.
“Unfortunately, we’re kind of got the wrong deal here, because we don’t operate in the ocean – we never have,” Peace said. “This was brought in by foreign carriers and Canadians that brought aquatic invasive species into the Great Lakes. So, now we’re trying to figure out how to deal with it. But the problem is, there’s no system that actually works in the freshwater for the amount of cargo and ballast that we use.”
Ram noted regulations from the International Maritime Organization encourage new-built ships to install ballast water treatment systems. The guideline, created in 2020, outlines how ships could test local water from samples at the port or in the direct harbor.
Though these regulations exist, Ram said there is uncertainty if they’ll be enforced.
Even with concerns over the effectiveness and enforcement of ballast water exchange systems, cargo shipping on the Great Lakes does have economic benefits. Waterborne transportation savings are about $3.9 billion per year, Peace said, and the efficiency of moving commerce via cargo has some positive implications for social justice and social equity.
“We’re not cutting across your lawn or in areas where people are underprivileged,” Peace said. “We’re operating strictly from port to port. We’re not like the railroads or they’re going through your backyard. So it’s a much more efficient and effective way to move commerce.”
This story was reported in partnership with the University of Michigan’s Detroit River Story Lab, an interdisciplinary, grant-funded initiative that partners with regional organizations to reconnect communities with the river and its stories.