Effects of Artificial Illumination on Intertidal Communities As A Consequence of Coastal Urbanisation

Coastal urbanization is often accompanied by the replacement of natural substrata by artificial structures, which causes coastal habitat modifications, losses of species richness, diversity and microhabitats diversity and favours the settlement of non-native species. The impact that coastal defence structures cause in the intertidal community is further favoured by the anthropic pressures produced in heavily populated areas (such as pollution or the collection of intertidal organisms). Among these, the effect of artificial lights on intertidal communities is practically unknown, even though that the behaviour of many intertidal vagile organisms is synchronized with circatidal and circadian rhythms. Considering that large areas of natural and artificial habitats are exposed to artificial illumination, this review exposes the current knowledge in this matter in order to evaluate the importance of this disregarded impact. Nocturnal lighting can increase stress in intertidal communities, modifying the predation rates and community dynamics. Likewise, lights may favour visual foragers and favour crepuscular behaviours. In consequence, light pollution should be considered in future conservation strategies and more ecological coastal structure designs.