KIOST Identifies Impact of Hull Underwater Cleaning Robot Byproducts on Marine Ecosystems for the First Time Worldwide

Identifying Changes in Plankton Community Structure and Function Caused by Hull Cleaning Wastewater (HCW)

The Korea Institute of Ocean Science and Technology (President Lee Heeseung, KIOST) has identified the impact of hull cleaning wastewater (HCW), a byproduct generated by hull underwater cleaning robots, on the structure of marine biological communities, and published the research results in an international academic journal.

Graphic Summary of Closed Ecosystem Evaluation Using Hull Underwater Cleaning Robot Cleaning Byproducts.

Hull fouling organisms that attach to the surface of ships reduce vessel speed, leading to increased fuel consumption and carbon emissions. To remove these organisms, cleaning technologies such as anti-fouling paints and underwater cleaning robots have been used.

However, HCW generated during underwater cleaning contains heavy metals such as copper (Cu) and zinc (Zn), as well as large amounts of suspended solids, which can pose potential risks to coastal ecosystems.

Hull fouling organisms refer to animals, plants, and microorganisms (such as barnacles and algae) that attach to or inhabit submerged ship surfaces or structures. These include bacteria and fungi, and can disrupt marine ecosystems.

Accordingly, KIOST is conducting research and developing evaluation technologies for the management of hull fouling organisms, including risk assessments of marine ecosystem impacts caused by the discharge of HCW at sea, through the Ministry of Oceans and Fisheries' technology development project (R&D).

The Ministry of Oceans and Fisheries' technology development project aims to develop hull fouling organism treatment technologies. The project period is from 2021 to 2025, with a total budget of 23.4 billion KRW.

In particular, the research team led by Dr. Baek Seungho and Dr. Lee Bora from the Ecological Risk Assessment Division of the KIOST South Sea Research Institute conducted the world's first assessment of the responses of marine phytoplankton, zooplankton, and benthic microalgal communities to various HCW dilution ratios (control, 1%, 5%, 10%) through a 1-ton scale mesocosm experiment using actual seawater.

The study found that at high HCW concentrations (5% or higher), the number of phytoplankton decreased sharply, and zooplankton populations also declined sensitively even at a 1% concentration. In contrast, benthic microalgae were more resilient and tended to increase as the concentration rose.

Additionally, exposure to high concentrations of HCW disrupted the balance among various species, resulting in only a few species with similar characteristics surviving. This suggests that the marine food web could become simplified, ultimately weakening the health and energy circulation of the marine ecosystem.

This research demonstrates that the byproducts of hull underwater cleaning robots are not merely waste, but complex pollutants that impact marine ecosystems. In particular, it is expected to provide scientific evidence for the need to establish HCW collection and treatment standards in the 'Biofouling Management Guidelines' currently under discussion by the International Maritime Organization (IMO).

Lee Heeseung, President of KIOST, stated, "Hull fouling organisms can pose a threat to the underwater environment and negatively affect global warming, so international management is necessary. KIOST will continue to conduct research related to the assessment of the harmfulness of hull fouling organisms to the marine environment and the conservation of marine ecosystems."

KIOST

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