Fig. 1

a The large-scale study area in the centre of the Netherlands (see inset) consisting of several connected waterbodies, including the focal lake Markermeer. Fish were monitored at large spatial scales through a network of acoustic receivers maintained by collaborators (n = 33, black triangles) throughout the lake system. The Marker Wadden archipelago is constructed in lake Markermeer, west of the ‘Houtribdijk’ dam that separates lake Markermeer and lake IJsselmeer. The Houtribdijk forms an incomplete boundary for fish with sluices at either end. b The Marker Wadden archipelago with sheltered gradual land–water transition shorelines leading into shallow littoral habitat, and the 30-m deep sand excavation pit created during the building of the archipelago on the southwest side. Fish were monitored at local spatial scales by a network of 13 acoustic receivers especially deployed for this study (black triangles). This created four sections varying in shelter and water depths; c Illustrative ground pictures of the four types of habitat indicated in panel b and as described in the methods