Natural Compounds

From an environmental point of view using natural materials is very beneficial. Natural products with antifouling properties have been identified from species of seaweeds, seagrasses, sponges, soft corals, and others. Chitosan is a good example that can be formed from the shells of shrimps. Other examples are furanones from algae, pepper extracts or menthol extracts.

Methodology

Natural Compounds can be incorporated as an active ingredient into paints and coatings. The chemicals are released into the water and deter (settlement stages) and/or kill the fouling (post-settlement).

Key Factors Positive

- Some natural products are very effective antifouling agents. For each major fouling type it is possible to find a specific natural product to prevent or reduce fouling.

Key Factors Negative

- Their efficacy and durability is not clear.
- Some actives may accumulate in the enviroment and have harmful effects while others are expected to be harmless. This needs to be assessed for each specific natural chemical.
- All actives including natural products are regarded as biocides by the BPD (EU Biocidal Products Directive) so need to go through normal registration procedures (which is a time-consuming and costly process).

Cost Benefit

These alternatives are much more costly than current biocidal net coatings. There are some products on the market incorporating natural antifoulants but they are rarely used due to high prices.

Conclusions/ Discussion

Potentially promising and good alternatives to toxic coatings. However, well proven commercial products for netting do not exist yet. Natural Compounds contain active ingredients so registration procedures may delay the registration and market introduction of new coatings.
A selection of non-commercial candidates has been field tested in CRAB. The general outcome is that the performance of these candidates is not very good. However it must be remarked that the tested systems are still under development.