more environmentally friendly route to stop biofouling. As the problem is worse where water moves slowly – giving organisms an easier time attaching – Demirel is looking into optimising ship design to speed up water flow across and around the hull, and especially those regions with sluggish flow, such as towards the stern.
“Maybe we can introduce some controlled roughness, or weird shapes, to increase the diversity of the flow. Or maybe we can dramatically change the ship shape and come up with some novel profiles,” he says.
Low fuel costs have meant ship designers have not focused too closely on how to prevent biofouling, he says. The emphasis on climate change and controlling greenhouse gas emissions is changing that. So too is the understanding that biofouling ecosystems transported across the seas themselves pose a threat.
In June this year, Australia will introduce new restrictions on biofouling to prevent the entry of invasive species. These can include the need to thoroughly clean the hull of a ship in the month prior to arrival. New Zealand already operates similar rules, and other places are considering them.
It’s only a matter of time before wider international rules are in place to control hull biofouling, Demirel predicts. It’s a logical next step, given the regulatory crackdown in recent years on the movement of invasive species through ballast water.
The problem within ballast water
Ballast is needed to stabilise ships, even very big ones, in rough weather. Depending on what cargo they carry, vessels typically pump millions of gallons of water into huge tanks before starting a voyage, and then discharge it when they reach their destination. As they pump in water, they also grab whatever sea life happens to be around. When they pump it out again, many of these creatures are still very much alive – and sometimes very unwelcome in the new surroundings.
“Ships have been transporting ballast water for hundreds of years and there are a few examples where it has had severe adverse effects” says Okko Outinen, a marine scientist at the Finnish Environmental Institute, with a special interest in ballast water.
Among the worst incidents was the 1982 introduction of an American jellyfish called a sea walnut to a port in the Black Sea. The creatures flourished, depriving local species of zooplankton, and spreading all the way to the Caspian Sea. Local fisheries, which had been worth hundreds of millions of dollars each year, were wrecked.
In the other direction, ships travelling west across the Atlantic managed to introduce zebra mussels from Europe to the Great Lakes of Canada and the US, where they have caused havoc. “They have very sharp shells that swimmers cut their feet on, and they are able to reproduce quickly and may occur in very high densities, as well as block underwater pipes used in cooling systems by local industries,” Outinen says.
In response to the growing threat and costs of invasive species spread by biofouled ballast water, the International Maritime Organisation (IMO) drew up regulations in 2004. These came into force in 2017 and declare that “ships must manage their ballast water so that harmful aquatic organisms and pathogens are removed or rendered harmless before” it is released.
It’s a big change for ship operators, Outinen points out. “So, at the moment we are in an implementation and experience-building stage, with the penalisation rules not being fully implemented or enforced yet,” he says. “We’re now figuring out everything related to how ballast water treatment systems work in different freshwater and marine waters. How do we monitor and sample ballast waters in a reliable, quick and cost-efficient manner? How do we detect how many organisms are viable or living? And many other similar practical details.” Once these issues have been worked out, the rules are scheduled to be more rigorously enforced in 2024, he adds.
Some of the problems posed by biofouling and ballast water, such as the transfer of invasive species, are the same. So are some of the possible solutions. One is using ultraviolet light to kill unwanted sea life. In an echo of the Royal Navy’s brainwave to install copper sheets back in 1761, some are experimenting with high- tech tiles that contain ultraviolet light bulbs, which can be fitted to a ship’s hull. If it catches on, then who knows maybe “UV bottomed” will be the latest maritime phrase to enter the English language.
This article appears courtesy of China Dialogue Ocean and may be found in its original form at
https://bit.ly/3bhg2E6 86 | The Report • September 2022 • Issue 101
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