Basal species can be limited by different elements in different ecosystems. If spatial flows from close habitats bring those elements, we expect them to enhance productivity at local and regional scales via spatial complementarity. Moreover, animals may transfer nutrients in a more labile form increase this positive effect further. We tested these hypotheses in a meta-ecosystem experiment with a fish. We manipulated the presence and nature of spatial flows (top consumer excretion vs detritus flow) connecting ecosystems. Our results stress the importance of accounting for flow quality in addition to flow quantity.