Creating new littoral zones in a shallow lake to forward-restore an aquatic food web

Eighteen different locations at the shorelines of the Marker Wadden archipelago in the Netherlands were sampled monthly between May and August 2020. Three different taxonomic groups were collected by various sampling techniques: zooplankton, macroinvertebrates and young-of-the-year fish. Meso-zooplankton densities were assessed by filtering 30 L of water through an 80-μm mesh size plankton net and condensing the sample into a 50 ml tube. Rotifera densities were assessed by filtering 1 L of water through a 30-μm mesh size plankton net into a 50 ml tube. Densities of pelagic macroinvertebrates in the water column were assessed by placing an open metal cylinder (ø 50 cm, 50 cm high) within 5 m from the waterline in the water at a depth between 20 and 30 cm and catching all pelagic macroinvertebrates in this enclosed area with a small dip net (13 × 10 cm, 1 mm mesh size). Benthic macroinvertebrates were sampled by taking one sediment core (ø 6 cm, depth 10 cm) in the metal cylinder and sieving the sample over a 0.72 mm mesh. Young-of-the-year (YOY) fish catch-per-unit-effort (CPUE) was assessed by means of multiple fishing gears that increased in mesh sizes over the season to accommodate for the increasing body lengths and swimming speeds of the fish over the season. In May, two types of dip nets (21 × 21 cm, mesh 0.5 mm, and 55 × 70 cm, 3 mm mesh) were used, to which from June until August additional seine netting (length 15 m, height 2.5 m, mesh-size 10 mm from knot to knot) was added. Sampling always occurred during daytime and at wind speeds <4 Beaufort. Data were analysed for spatial and temporal variation in generalized linear mixed-effects models as described in the two linked publications.