Coastal lagoons are highly productive areas that act as habitat for many species, specially as a nursery for fishes and as a staging post for migratory birds. They are semi-enclosed coastal systems (SECS), separated from the ocean by sand barriers created by the deposition of sediments, and connected to the sea by restricted openings which can sometimes close and reduce the water exchange leading to eutrophication.

Ria do Alvor is a coastal lagoon located in the south of Portugal with a high biodiversity. Few studies have taken place in this valuable ecosystem, being this study the first one that gather information about its food web interactions.