First representation of the trophic structure and functioning of the Portuguese continental shelf ecosystem: insights on the role of sardine

In this study, we analyse the structure and functioning of the Portuguese continental shelf ecosystem and investigate the role of sardine (Sardina pilchardus) using the Ecopath mass-balance approach. An Ecopath model was configured to represent the continental shelf waters in the period 2006 - 2009. The model showed that biomass was concentrated in low and intermediate trophic levels as in other upwelling areas. Several low and medium trophic level groups are identified as dominant groups in the ecosystem (e.g. zooplankton, macrozoobenthos, sardine, chub mackerel (Scomber colias), and demersal and benthopelagic invertivorous fish). Furthermore, low trophic level groups are responsible for the main energy flows, and overall higher impact on the ecosystem, emphasizing the importance of bottom-up control of the ecosystem structure. Our results are relevant to understand structure and functioning of this ecosystem and constitute an important step towards an ecosystem approach to fisheries management in the study area