Diversity and seasonal variations in Periphyton composition in freshwater ecosystems

Abstract

Periphyton is a community of organisms, such as microscopic protozoan, algae, that live attached to stones, plants or other submerged surfaces in the water. Periphyton are primary producers and an important foundation of many water ecosystems food webs. These organisms also stabilize substrates and serve as habitat for many other organisms. Periphytonic organisms are used as biological indicators, because they are sensitive to water quality. The aim of this work was to try to establish composition and diversity of periphyton in stagnant and flow freshwater systems and evaluate the ecological quality of these ecosystems on the basis indication of periphyton. Periphyton was investigated in Nemunas river and in Kaunas lagoon. Periphyton samples were collected from the stones at regular intervals to compare periphytonic community structure and to examine its temporal changes. The results showed differences in the periphyton structure depending on the month (season) and on the type of water system. Totally, were collected and identified 15 species and 13 genus of periphyton. The dominant genus in all locations was Euglena sp. and diatoms Navicula lanceolata, Craticula cuspidata (Navicula cuspidata), Amphora ovale. All these organisms are good water contamination indicators. Navicula sp. and Euglena sp. were found more abundance in Kaunas lagoon than in Nemunas river, so this preliminary results shows that lagoon is a higher pollution level.