CHARACTERISTICS OF THE PLANKTONIC ALGOFLORE FROM DOROBANTI, ARONEANU, CIRIC I, II AND III LAKES (IASI COUNTY)

After the setting of Ciric river by building some barrages, the lakes Dorobanti, Aroneanu, Ciric I, II and III were formed, their total surface being of about 123 ha. When the lakes were formed, processes of colmating and accumulating used waters started, these waters were coming from the side localities and from the Ciric recreation area. Water quality from these aquatic mediums was evaluated on these conditions, knowing the diversity of phytoplankton algae, the phytoplankton evolution and the specific structure of algoflore. Researches concerning phytoplankton of the Ciric river area (May, 2006) show the diatoms dominance (BACILLARIOPHYTA) at Dorobanti – mijloc and Parau Ciric – Pod stations, of the CHLOROPHYTA group at Ciric II, Ciric I and Aroneanu stations and the big heaviness of the CYANOPHYTA group at Dorobanti – Dig station (in this moment, this station is attested by the algologic indicators as being very polluted). During the first cold period of the year 2007, biodiversity is reduced (because of the pollution), and the genus analysis shows the dominance of the green algae (CHLOROPHYTA) at the first 4 lakes: at Dorobanti station the biggest numerical heaviness is presented by Monoraphidium tortile (W.et G.S.West) Kom.-Leg. – 21.18% of the total algae; at Aroneanu station Monoraphidium contortum (Thur.) Kom.-Leg - 25.81% and Monoraphidium tortile (W.et G.S.West) Kom.-Leg. – 18.54% are dominant; at Ciric I, Monoraphidium contortum (Thur.) Kom.-Leg – 48.88%, at Ciric II, Monoraphidium contortum (Thur.) Kom.-Leg – 55.66%, and at the last lake, Ciric III, the biggest numerical heaviness was observed by Diatoma elongatum (Lyngb.) Agardh. (Bacillariophyta) – 47.70% of the total planktonic algae determined at that station. Numerical densities of phytoplankton from the 5 studied lakes varied between the values of 1,105 – 3,830 exemplars algae/ml in March, 2007, and 15,603 – 73,759 exemplars algae/ml in November, the same year. These values show an important pollution degree of the investigated ecosystems. As it follows, researches are necessary for a period of several years in order to point out the implied processes and phenomena complexity and evolution in those aquatic ecosystems that are affected by anthropic pollution.