Role of macrophytes in structuring littoral habitats in the Vistula Lagoon (southern Baltic Sea)

Summary The objective of the research conducted in the years 2011–2014 in the near-shore zone of the Vistula Lagoon was the verification of the hypothesis that in the coastal lagoon, similarly as in inland waters, habitat conditions can be substantially modified by macrophytic vegetation, depending on the represented life form and its abundance. The research was conducted in the zone of emergent plants (reed rush composed of Phragmites australis ) and in the zone of submerged plants occurring as scattered patches of Potamogeton perfoliatus and Stuckenia pectinata . The hypothesis was supported only in the case of the reed rush which substantially modified water insolation, temperature, and oxygenation, as well as the grain size composition of sediments, and concentration of organic matter contained in the sediments. Patches of submerged vegetation had insufficient surface area and were too scarcely overgrown by plants to considerably affect the habitat conditions and weaken the strong mechanical effect of waves and rate of water exchange between the littoral and open water zone.