Drift velocity of morphologically diverse macrophytes and macroplastic particles under current and wind forcing

This dataset comprises drift velocity measurements for 22 morphologically diverse macroalgae species (n = 54), the seagrass Zostera marina (n = 7), and macroplastic particles (n = 6). Samples are divided into positively buoyant samples drifting at the surface, as well as negatively buoyant samples drifting on the bottom. Macroalgae morphologies range from filamentous forms such as Ceramium virgatum to sheet-like species including Ulva, as well as more sturdy species such as Fucus vesiculosus and Ascophyllum nodosum. Detailed morphological descriptions and images for the macrophyte species are provided in DOI: 10.1038/s41598-025-28893-8. Detailed images of the macroplastic particles are provided in the accompanying publication. Macroplastic particle samples are identified by labels beginning with "P-". All measurements were conducted in a racetrack flume at the Royal Netherlands Institute for Sea Research (NIOZ), Yerseke. The drift velocity was measured five times per replicate and calculated by dividing the covered distance (5 m) by the recorded time. Each sample was released 1 – 1.5 m upstream of the measurement start to ensure constant velocity during the measurement. Drift velocity was measured at three current velocities (0.1, 0.2, and 0.4 m/s). For positively buoyant species, measurements at each velocity were additionally conducted with wind applied in the same direction as the current velocity. Ulva gigantea and the macroplastic particles were collected in June 2024 in Yerseke, Netherlands (51°30'09.0N, 4°02'39.7E). All other macrophytes were collected in June 2024 in the Kiel Fjord, Germany (Schilksee, 54°25'16.3N 10°10'43.1E, Mönkeberg, 54°21'20.92N 10°10'41.97E, and between Strande and Bülk light house, 54°26'57.4N 10°11'37.6E).Macrophyte species measured: Fucus vesiculosus, Fucus serratus, Gracilaria vermiculophylla, Ceramium virgatum, Polysiphonia stricta, Spermothamnion repens, Ahnfeltia plicata, Furcellaria lumbricalis, Coccotylus truncatus, Delesseria sanguinea, Cladophora flexuosa, Rhodomela confervoides, Pyropia leucosticta, Ulva clathrata, Ulva linza, Kornmannia leptoderma, Bryopsis hypnoides, Acrosiphonia centralis, Ulva gigantea, Chorda filum, Ulva compressa, Ascophyllum nodosum and Zostera marina.Macroplastic particles measured: Piece of a net, piece of foil, juice pouch, small plastic bottle, and a bottle cap upside and upside down.