Chemical arsenal of sea anemones: antifouling effects on bryozoan larvae and interspecific interactions

Biofouling organisms threaten biodiversity as their pelagic larvae settle on submerged surfaces and are transported on the hulls of ships. Conventional antifouling paints are effective but release toxic biocides. We evaluated a nature-based alternative using exudates from the native sea anemone <i>Anthothoe chilensis</i>. Crude and diluted exudates (100%, 70%, 50%) were tested on larval settlement and behaviour of the bryozoan <i>Bugulina flabellata,</i> and compared with seawater and exudates from the non-native <i>Anemonia alicemartinae</i>. Settlement was strongly reduced under 100% <i>A. chilensis</i> exudate, while diluted treatments did not differ from controls. Larvae also swam longer and explored less, indicating behavioural deterrence. By contrast, <i>A. alicemartinae</i> exudate did not affect behaviour. Adult interactions showed asymmetric chemical interference. These results suggest that <i>A. chilensis</i> exudates act as selective chemical deterrents influencing recruitment and competition, pending comprehensive chemical characterisation and toxicity assessment, to determine their suitability as potential antifouling agents.