Analysis of the trophic role of Mediterranean seagrasses in marine coastal ecosystems: a review

Seagrasses form high-productivity coastal ecosystems, providing habitats for many organisms, including species of commercial value. They play a significant role as a direct food source for herbivores and also enter detrital food webs. In this review, the trophic ecology of Mediterranean seagrass ecosystems is revised, with major emphasis on Posidonia oceanica, the most extensively studied seagrass. The major topics are the role of herbivory and detritus, the contribution to littoral fish production, exportation to other ecosystems and the seagrass role as a vector of anthropogenic nutrients into food webs. Topics are discussed by analysing both conventional knowledge and new insights derived from the application of carbon and nitrogen stable isotope analysis. In conclusion, perspectives for future research are highlighted, with particular emphasis on areas demanding further study and on the effects of seagrass decline on trophic organisation in coastal environments.