Assessment of macrophyte store and accumulation of nutrients by aquatic vegetation in the Curonian Lagoon of the Baltic Sea

One of major components of aquatic ecosystems are macrophytes - the large metaphytes normally develop in conditions of exuberant humidification. This group of hydrobionts represents an initial part in circulation of matter and energy as primary producers of organic matter. Macrophytes influence chemical and physical properties of water by accumulation of nutrients. Besides they are habitats for many organisms at various stages of development, including nesting birds, fish eggs and larvae. That is why assessment of macrophyte store and accumulation of nutrients in macrophyte tissues became the one of important objectives of environmental monitoring and management. In August 2005 the geobotanical mapping of the Curonian Lagoon coast from the research vessel to evaluate distribution of reed (Phragmites communis Trin.) and bulrush (Scirpus lacustris L.) was conducted. The area of macrophyte thickets is approximately 480 ha for reed and 305 ha for bulrush. At the same time biomass samples of reed and bulrush (not less then 10 samples per one plant community, 61 samples in total) were taken along the coastline. The samples were weighed in air-dry state; the data were processed with the computer programs Microsoft Excel 97 and Statistica. The average air-dry biomass is 993 g/m2 for reed, and 470 g/m2 for bulrush. So the macrophyte store in the Russian part of the Curonian Lagoon is approximately 4766,4 tons of air-dry mass for reed and 1433,5 tons for bulrush. The average values of concentrations of phosphorus in tissues of dominating macrophyte species (in mgP/g of dry matter) sampled in August 2005 in the Curonian Lagoon and analysed with a photometer are 6,7 mgP/g for reed and 4,1 mgP/g for bulrush. For concentrations of nitrogen the values are 28,8 and 21,3 mgN/g accordingly.