Do artificial structures affect the diet of the limpet Patella caerulea Linnaeus, 1758?

Abstract

The current scenario of global change and the increase of human population in coastal areas is leading to the introduction of numerous man-made structures into the coastal environment. Those artificial structures provide different services at the expenses of habitat loss and a range of widely documented ecological impacts. Limpets are keystone species that are worldwide established in these artificial habitats. However, little is known about the impact of artificial coastal defence structures on the diet of limpets. Therefore, the aim of this study was to evaluate if different kinds of artificial structures (cubes, rip-raps, seawalls and tetrapods) across a geographical gradient (western to eastern Alboran Sea), could affect the food consumption of the limpet Patella caerulea by using carbon and nitrogen isotopes analysis. Our results suggested that for certain localities, there was a shift in the trophic niche of P. caerulea inhabiting artificial substrates in comparison with the nearest natural rocky shore. However, patterns were not consistent for all localities and different types of artificial structures, which reinforces the importance of considering local scales for conservation and management purposes. Finally, δ15N ratio in P. caerulea is a good indicator of eutrophication at regional scales, by showing a gradient of enrichment in the limpet tissues from oligotrophic to eutrophic waters within the Alboran Sea.