The Preventive Advantage: Biofouling Management in a Warming Ocean

Water temperatures in the Southwest Pacific hit record levels in 2024 (World Meteorological Organization, 2025). For anyone maintaining vessels or marine infrastructure, that has two practical consequences: things foul faster, and things corrode faster. Both land on operating cost, asset life and biosecurity obligations.

Two problems, not one

Biofouling is both a performance problem and a biosecurity problem. Growth on submerged surfaces slows the vessel down, and it also carries organisms from one port to another. Shipping is one of the main pathways for invasive aquatic species worldwide (International Maritime Organization, 2023).

What it costs to run

Even a light biofilm raises frictional resistance by more than 10% (Arndt et al., 2021). Let it develop into barnacles and tubeworms and the power needed to hold speed can climb by up to 80%. Computational fluid dynamics work puts the frictional resistance increase at 85.7% under moderate fouling (Choi et al., 2024).

That leaves you choosing between slowing down and burning more fuel. On commercial vessels, where fuel is roughly half of operating cost, neither option is cheap (Arndt et al., 2021).

Fouling also affects how the vessel handles. Extra hydrodynamic volume and surface roughness degrade rudder effectiveness and turning response, which extends turning circles and hurts station-keeping. That matters most for offshore support vessels, research platforms and anything working in confined water (Choi et al., 2024).

If you want to put numbers against your own vessel, our Hull Fouling Cost Calculator uses the University of Melbourne's underwater scanning research to estimate the fuel and emissions penalty.

What it costs everyone else

Estimates suggest shipping is responsible for 55% to 70% of established coastal and estuarine invasive species introductions, and that biofouling may account for more introductions than ballast water in many regions (GloFouling Partnerships, n.d.).

Once an organism establishes, it outcompetes native species, can introduce new pathogens, and changes the habitat itself. The damage runs to hundreds of millions of dollars a year through lost fisheries, damaged coastal infrastructure and disrupted operations, and unlike a fuel bill, it is not recoverable (GloFouling Partnerships, n.d.; International Maritime Organization, 2023).

The conditions have changed

Fouling has always been a biosecurity risk. What is new is the rate.

The Southwest Pacific recorded water temperatures in 2024 above anything in the historical record (World Meteorological Organization, 2025; The Strategist, 2025). Warmer water means faster growth, shorter reproductive cycles, and activity through seasons that used to be dormant (Arndt et al., 2021).

Ocean acidity has risen roughly 30% since the pre-industrial era, with surface pH dropping about 0.1 units from 8.2 to 8.1 (NOAA, n.d.; IAEA, n.d.; Secretariat of the Pacific Community, 2022). Because the scale is logarithmic, that small-looking shift is a substantial change in hydrogen ion concentration. It speeds up corrosion (The Strategist, 2025) and it changes which transported species survive in a new environment. Marine heatwaves add algal blooms on top, creating short periods of very high fouling pressure (World Meteorological Organization, 2025).

The practical upshot: waters that used to produce moderate fouling now produce tropical-rate fouling (Arndt et al., 2021). Vessels working across a wide area are carrying more biosecurity risk than their maintenance schedules assume.

Why fixed intervals stopped working

Most maintenance cycles were built around fouling rates that no longer apply. Warmer, more acidic water and heavier commercial demand have made the old accumulation models optimistic, which makes drydocking intervals set against them optimistic too (The Strategist, 2025).

Moving from reactive to preventive maintenance is not a new idea. Aviation and advanced manufacturing have run condition-based and predictive maintenance for years. What has changed in shipping is that the technology to assess condition in the water is now available, the cost-benefit case is documented, and the compliance requirements have tightened (International Maritime Organization, 2023).

In-water sustainment is not a replacement for drydocking. It is what keeps hydrodynamic efficiency and corrosion under control between dockings, which is what lets you extend the interval rather than gamble on it.

Where MarineStream fits

We build and operate the systems for doing this work.

Our filtration hardware made compliant in-water hull cleaning possible again. It is designed to meet IMO biofouling guidelines and port state requirements, capturing everything the clean removes so the work can happen at berth instead of in a dock. The cleaning record, including discharge results, lands on one auditable trail per vessel.

The ROVs work the same way. Inspection data goes straight into the MarineStream platform, so the vessel owner holds the condition history rather than requesting it from a contractor after each job. Stakeholders can watch a survey live, and the record cannot be quietly edited afterwards.

Some clients want us to run the whole program. Others want to build the capability in-house and use us for the systems, the training and the hard jobs. Both work, and we would rather help you pick the right one than sell you the bigger one.

Contact us if you want to talk through what preventive biofouling management would look like for your fleet.

Where this ends up

Ocean warming and acidification are not a phase that passes. They are the conditions maintenance strategies now have to be designed against (The Strategist, 2025; NOAA, n.d.; IAEA, n.d.).

The question for operators is not whether to shift to preventive biofouling management. It is how quickly they can get a program running that reflects the water their vessels are actually in.

References and sources

• Arndt, E., Robinson, A., and Hester, S. (2021). Factors That Influence Vessel Biofouling and its Prevention and Management. Final Report for CEBRA Project 190803. Melbourne, VIC: Centre of Excellence for Biosecurity Risk Analysis (CEBRA). Available at: https://cebra.unimelb.edu.au/__data/assets/pdf_file/0010/3822922/Endorsed-CEBRA-190803-Final-Report.pdf

• Choi, J., et al. (2024). Resistance and speed penalty of a naval ship with hull roughness. Ocean Engineering. Available at: https://strathprints.strath.ac.uk/90318/1/Choi-etal-OE-2024-Resistance-and-speed-penalty-of-a-naval-ship-with-hull-roughness.pdf

• Davidson, I., Cahill, P., Hinz, A., Kluza, D., Scianni, C., Georgiades, E. (2021). A Review of Biofouling of Ships' Internal Seawater Systems. Frontiers in Marine Science. Available at: https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2021.761531/full

• GloFouling Partnerships. (n.d.). Biofouling and Invasive Aquatic Species. Available at: https://www.glofouling.imo.org/the-issue

• International Atomic Energy Agency (IAEA). (n.d.). What is Ocean Acidification? Available at: https://www.iaea.org/newscenter/news/what-is-ocean-acidification

• International Maritime Organization. (2023). 2023 Guidelines for the control and management of ships' biofouling to minimize the transfer of invasive aquatic species. Resolution MEPC.378(80). Available at: https://wwwcdn.imo.org/localresources/en/KnowledgeCentre/IndexofIMOResolutions/MEPCDocuments/MEPC.378(80).pdf

• International Maritime Organization. (2025a). Guidance on in-water cleaning of ships' biofouling. MEPC.1/Circ.918. Available at: https://www.imo.org/en/ourwork/environment/pages/biofouling.aspx

• International Maritime Organization. (2025b). Marine Environment Protection Committee (MEPC 83), 7 to 11 April 2025. Available at: https://www.imo.org/en/mediacentre/meetingsummaries/pages/mepc-83rd-session.aspx

• International Maritime Organization. (n.d.). Biofouling. Available at: https://www.imo.org/en/ourwork/environment/pages/biofouling.aspx

• National Oceanic and Atmospheric Administration (NOAA). (n.d.). Ocean Acidification. Available at: https://www.noaa.gov/education/resource-collections/ocean-coasts/ocean-acidification

• Secretariat of the Pacific Community. (2022). Ocean acidification: A tide of challenges for Pacific Islanders. Available at: http://www.spc.int/updates/blog/2022/08/ocean-acidification-a-tide-of-challenges-for-pacific-islanders

• The Strategist - Australian Strategic Policy Institute. (2025). More hull fouling, more corrosion: effects of warmer South Pacific waters on navies. Available at: https://www.aspistrategist.org.au/more-hull-fouling-more-corrosion-effects-of-warmer-south-pacific-waters-on-navies/

• World Meteorological Organization. (2025). Pacific 2024 Climate Report. Available at: https://wmo.int/sites/default/files/2025-06/Pacific_2024%20final.pdf