Epiphytic communities on sawgrass (Cladium mariscus Pohl.) in Plitvice Lakes National Park (Croatia)

Background and Purpose: The investigation of epiphytic community was carried out on growing and dead stalls of sawgrass (Cladium mariscus Pohl.) from Plitvice Lakes National Park. The natural phenomenon of karst was protected by adding the Lales to the UNESCO list of World Heritage in 1979. Recently, sawgrass became the main constituent of macrophyte vegetation in this region. Increase in density of submerged vegetation indicate higher trophic level. Materials and Methods: Samples of epiphyton were collected from stalls at a site 1.5 m from shorelines and 0.5 m below water surface. In the laboratory, epiphyton were carefully removed from stalks by scalpel and rinsing with distilled water: Microphytes were determined, as well as their relative abundance, saprobity values of species, and the degree of water saprobity. Results and Conclusions: During the investigation, 125 microphyte species were established (64 on growing and 113 on dead stalls). Diatom species were predominant in all samples. Only 42% species were common for both types of substrates. Especially on dead stalls, a mass development of filamentous bacteria, Cyanobacteria and Chlorophyta, was observed, indicating higher saprobic and trophic level in the ecosystem. Saprobity index of epiphytic communities ranged from 1.5 to 1.9 on growing stalks and from 1.8 to 2.3 on dead stalls.