Coastal Ecosystems and Economies Hang in the Ballast
Fight to repel bioinvaders hindered by wartime disruptions and shipping growth rates projected to outpace the efficacy of preventative technology and regulations.
Cargo travels with unwelcome passengers – marine organisms from distant waters that, if discharged while still viable, could attack biodiversity and coastal economies anywhere.
Curtailing ecological damage with technology and international regulations is difficult enough without giving potential bioinvaders decisive time advantages.
Yet, in scenarios – short and long-term – timing doesn’t favor those who would prevent invasive species from taking over, according to two recently published scientific papers by separate groups of researchers.
A July article in Biological Invasions alerts, “Closure of the Strait of Hormuz may trigger a bioinvasion super-spreader event,” while a Sea Aggie’s Tuesday, Aug. 18, paper in Nature Sustainability warns that modern prevention methods can’t keep pace with long-term shipping growth.
With the U.S.-Iran conflict strangling passage through the Strait of Hormuz, scientists see prolonged opportunities for marine organisms to collect on hulls and incubate in ballast tanks of hundreds of ships delayed in the warm waters of the Persian Gulf.
Even rerouting trade could complicate efforts to curtail the movement of marine organisms.
“One possible aspect that hasn’t been explored much is how the conflict could reshape global oil and gas trade, leading to changes in shipping routes and, consequently, marine invasion patterns,” said Dr. Zhaojun Wang of Texas A&M University at Galveston.
The assistant professor of marine and coastal environmental science in the College of Marine Sciences & Maritime Studies researches the variables that complicate efforts to curtail the introduction of invasive species when ships arrive in port.
“When a war or other cause of supply chain disruptions persists long enough, or when key shipping corridors such as the Panama Canal experience severe drought, the ships may seek alternative routes and adjust their network, so that will impact the whole behavior of ships and the final invasion risk,” Wang said.
Wang’s most recent article, “Integrating shipping growth and ballast water management to assess invasive species risks,” notes that treatment and international regulations have reduced such risks in recent years.
Still, all gains could easily be lost as shipping rates escalate worldwide unless compliance and technology improve drastically.
Drs. Zhe Dong, an independent researcher from Santa Clara, California, and Sarah A. Bailey of Fisheries and Oceans Canada’s Great Lakes Laboratory for Fisheries and Aquatic Sciences in Burlington, Ontario, co-authored the paper with Wang.
“The problem is not that the ship operators don’t want to comply. They try their best. They use the technology.”
– Dr. Zhaojun Wang, assistant professor of marine and coastal environmental science in the College of Marine Sciences & Maritime Studies at Texas A&M University at Galveston
Their paper projects that the risk will at least double over the rest of the century from 2018 levels, when present regulations were beginning to take effect. Some estimates go as high as 10 times as much.
“The problem is not that the ship operators don’t want to comply,” Wang said. “They try their best. They use the technology.”
Instead, the problems lie within the limits of the technology and in conditions that reduce its effectiveness, such as high turbidity, elevated organism concentrations, and inadequate equipment inspections.
If not adequately treated, the water taken in by vessels for stability during cargo loading at one port and released during cargo unloading at another can introduce nonindigenous species to an area.
“After arrival, introduced populations may be further redistributed through regional vessel movements, coastal circulation, and floating debris, allowing invasion risk to extend beyond the original point of introduction,” according to the paper. “Because established marine invasions are difficult to reverse, biosecurity policy has placed strong emphasis on preventing organism delivery before establishment occurs.”
The International Maritime Organization’s Ballast Water Management Convention and U.S. Coast Guard require ballast water treatment systems that can filter, disinfect, and otherwise limit viable organisms.
“The regulation is pretty effective at present, but considering the future possibility of increased shipping traffic, the invasion risk will remain very high,” Wang said.
By 2050, global shipping could surpass 2.1 million voyages annually, up from a mere 1.3 million in 2018. Some forecasts put it at as many as 11.7 million voyages by 2100, a staggering change that will magnify every margin of failure in ballast treatment processes.
“These results indicate that technology adoption alone may be insufficient to counteract the ecological consequences of expanding maritime trade,” according to the paper. “More adaptive ballast water governance, improved compliance, and sustained optimization of treatment performance will be needed to reduce future biological invasion risks in a rapidly intensifying global shipping system.”
Wang suggested that port-based systems could improve the effectiveness of pre-discharge treatment by supplementing onboard ship technology.
The paper also advocates taking steps to ensure crew familiarity with system operation, to provide vessel-specific guidance for atypical uptake or discharge conditions, and to conduct regular testing to verify systems are operating properly.
Better understanding invasion risk, in peacetime or war, remains a forceful goal as Wang and other Aggie researchers work together to understand better the impacts and benefits of maritime activity around the world.
