Foaming at the mouth: direct and indirect exposure to seafoam affects the behaviour of the periwinkle Littorina littoreaBiology & Ecophysiology

Solène Cazalis-Henry¹, Nicolas Spilmont¹, Elsa Breton¹, Florence Elias², Laurent Seuront^1,3,4

¹Univ. Lille, CNRS, Univ. Littoral Côte d’Opale, IRD, UMR 8187 LOG, Station Marine de Wimereux, France - ²ESPCI–PSL–Sorbonne Université–Université de Paris, 75005 Paris, France - ³Tokyo University of Marine Science and Technology, Japan - ⁴Rhodes University, South Africa

Foam formation is common in marine environments and its accumulation on coasts may have important ecological, social and economic implications. Although the presence and important role of foam deposits in the ecology of sandy coasts and estuaries is well established, their impact on the structure and function of rocky intertidal ecosystems remains under-documented. Through our research work, we studied how different foams, either natural or artificial, could influence the activity patterns of the periwinkle Littorina littorea under laboratory conditions. Our results showed that Littorina littorea actively avoided the foam and, in addition, never went through it. Furthermore, we observed a reduction in search activity in the presence of seafoam, as well as remote detection of chemical signals from seafoam. In contrast, Littorina littorea individuals exposed to neutral artificial seafoam exhibited no foam-specific behaviour and moved through it. Our results suggest that foam accumulation on intertidal rocky shores may have important consequences for species relying on airborne chemosensory and tactile cues for movement, foraging, and mating. Further investigations are needed to highlight the potentially significant ecological consequences in rocky intertidal ecosystems of the accumulation of long-lived foams, enhanced by strong hydrodynamics and a high organic matter content.