When the ocean clings on: Inside the new wave of marine anti-fouling with Prof. Christine Bressy

In this episode of BlueTech Around the World, I sat down with Prof. Christine Bressy, polymer chemist and head of the MAPIEM laboratory in Toulon (France).

With over 20 years at the crossroads of chemistry, engineering, and environmental science, she unpacks where anti-fouling stands, what’s next, and why “one silver bullet” doesn’t exist.

From traditional paints to AI-powered decision tools, we explore how the field is evolving and why multidisciplinary approaches are key to success.

Biofouling 101: What is marine biofouling?

“First you have bacteria that settle within hours, forming a biofilm. Then come diatoms, and within a week or two, you see mussels, barnacles, and tube worms forming a living carpet on the surface,” Christine explained.

Think of a freshly immersed surface as an empty lot. Within hours, bacteria lay down the foundations. A few days later, diatoms join in, and within two weeks the community expands into a dense neighborhood of algae, worms, mussels, and barnacles.

• Soft foulers (like algae) are relatively easy to remove.

• Hard foulers (like barnacles) cling tightly with calcareous “cement.”

With more than 4,000 fouling species worldwide, each with different adhesion mechanisms, biofouling depends on geography, season, depth, and even surface chemistry. That complexity makes developing universal anti-fouling solutions one of the great R&D challenges.

And the consequences are costly. Drag can increase fuel consumption by up to 40%, turning ships into “sailing anchors.” For aquaculture, fouled nets reduce water circulation and fish welfare. On sensors, fouling corrupts environmental data. And in sea chests, it spreads invasive species across oceans.

Two main coating families: to kill or to release

Today, anti-fouling coatings fall into two broad categories:

1. Biocidal anti-fouling paints

These coatings gradually release active molecules, often copper compounds combined with “booster” biocides.

“They work in both static and dynamic conditions, which is why they still dominate the market—around 90% of hulls still use them,” Christine said.

Although the International Maritime Organization banned TBT decades ago, copper-based formulations remain widespread due to their reliability.

2. Fouling-release coatings (biocide-free)

Instead of killing organisms, these silicone-based coatings create a surface with very low adhesion.

“Earlier versions only worked efficiently at 20 knots, but newer ones can be effective at just 5 knots,” Christine noted.

When ships move, hydrodynamic forces help organisms slip away. But in harbors or during long lay-ups, these coatings are far less effective. That’s where biocides still have an edge.

Static assets: Offshore wind, cages, sensors: different game

Movement-dependent coatings don’t help fixed structures like offshore wind turbines, aquaculture cages, or static sensors.

The solution is combining materials with maintenance strategies.

“The best approach is to combine fouling-release coatings with proactive cleaning, ideally by robots and keep it frequent before hard fouling sets in,” Christine explained.

Cleaning early prevents costly interventions, avoids damaging coatings, and limits microplastic release from aggressive late-stage scrubbing.

Environment & regulation: targeted action, minimum collateral

Biocides are designed to act on target organisms, but they can affect others.

“Biocides must be tested for their toxicity across different trophic levels—efficacy is only part of the story,” Christine said.

In Europe, only a limited list of actives are authorized under the Biocidal Products Regulation.

Ultimately, it’s about controlling exposure: if release rates are tightly managed, actives can be effective against fouling without becoming ecotoxic to non-targets.

The key is not just the molecule itself, but the dose at the ocean’s surface.

Innovation frontiers: What MAPIEM and others are building

At MAPIEM and in labs worldwide, research is accelerating.

Some highlights:

1. Advanced biocide-free surfaces

Amphiphilic coatings create surfaces with mixed hydrophobic and hydrophilic zones.

“They touch one domain and think it’s okay, then another, and decide ‘Nope.’ It confuses them and reduces settlement,” Christine said.

Biomimetic microtextures, inspired by shark skin, discourage attachment. Laser ablation or 3D printing can create these patterns, sometimes applied as films.

“You could apply them as films, but the process is expensive—unlike spray-on paints,” Christine noted.

2. Active or physical deterrents

Ultrasound, UVC light, micro-bubble curtains, and even electrically active surfaces (bacteria dislike certain electrical stimuli), all disrupt microbial colonization.

Robots can also “groom” surfaces before fouling hardens.

These physical deterrents disrupt microbial colonization but must be part of a hybrid strategy, not standalone:

“There’s no silver bullet; it’s the combination that delivers efficiency across conditions,” Christine emphasized.

3. The next wave: Biodegradable bio-polymers

“We’re aiming for coatings that are biocide-free and silicone-free. Ideally they’re made from marine-bacteria-sourced biopolymers—biodegradable and effective,” Christine explained.

• Biocide-free and silicone-free systems (concerns around silicone oils/surfactants persisting in sediments).

• Bio-sourced polymer matrices (e.g., polyesters produced by marine bacteria), engineered to be high-performance and biodegradable, reducing long-term accumulation when fragments enter the environment.

This is the frontier of blue biotechnology: using polymers produced by bacteria to create coatings that perform well but degrade harmlessly, closing the loop on sustainability.

Testing & standards: proving it works (and for how long)

Biocidal coatings are backed by international standards (ISO, national protocol). But for fouling-release and newer physical approaches, protocols lag behind.

“We need to know if coatings last 1, 2, even 5 years under specific navigation profiles—but new solutions still need custom test protocols,” Christine said.

This requires new test platforms, mixing chemistry with engineering, and always in collaboration with industry to reflect real-world conditions.

Digitalization & decision support

Even in paint, digitalization is making waves.

“Paint manufacturers now use software that, given your ship’s route, speed, and lay-up times, can recommend the optimal coating strategy,” Christine said.

This data-driven approach helps shipowners optimize OPEX, cut emissions, and align with decarbonization goals. It’s like having a digital “personal trainer” for your hull.

It’s a subtle yet powerful example of how data-driven tools can accelerate decarbonization and operational resilience.

Market adoption: slow but steady

Why is change gradual?

Biocides remain dominant because they’re familiar, cost-effective, and work in all conditions. But progress is happening:

• Fouling-release coatings are steadily improving.

• Regulations and decarbonization targets are pushing adoption.

• Offshore renewables and aquaculture are adapting shipping technologies to their unique needs.

“Industries are looking for low-tox and low-impact solutions, they’re borrowing from shipping but adapting to their unique environments,” Christine said.

Cross-sector spillovers

Sectors like offshore wind and aquaculture look to shipping for transferable solutions, then adapt with cleaning robotics and operational tweaks.

Constraints differ (e.g., fish welfare in aquaculture), but the mix-and-match toolbox applies across the blue economy.

What works for one sector often sparks solutions in another.

A word to the next generation

“There’s room to do a lot and to keep innovating for years, regulation and decarbonization goals will keep pushing the field. It’s a tight-knit community with exciting challenges and real-world impact. Feel free to join us.” — Prof. Christine Bressy

If you’re a student or early-career innovator seeking meaningful climate impact with hard technical puzzles, anti-fouling is a rewarding path into the blue economy. It’s where chemistry, biology, engineering, and climate action intersect.

Biofouling may be a natural process, but left unchecked it drags efficiency, raises emissions, and threatens ecosystems.

Anti-fouling innovation is about more than coatings: it’s about combining strategies—materials, robotics, digital tools, and regulatory frameworksto reduce impact while keeping the maritime world moving.

As Prof. Bressy reminded us, this is a field full of complexity, collaboration, and opportunity. The ocean may cling, but innovation is learning how to let go.

To learn more, visit https://mapiem.univ-tln.fr/

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