Explorations were done at the location Ilje, near Melenci. Novo Ilje 1 is a canal used for regulation of irrigation at the local fields. Novo Ilje 2 is a bog that dries out during the periods of low precipitation. Quantitative phytoplankton analysis of Novo Ilje 1 sample from 2003 determined that total amount of cells was 1.5 x 10**5 cell per liter. Total amount of cells in 2004 sample was 1.8 x 10**5 cell per liter. Quantitative phytoplankton analysis of Novo Ilje 2 sample from 2003 determined that total amount of cells was 1.7 x 10**5 cell per liter. Total amount of cells in 2004 sample was 3.1 x 10**5 cell per liter. Phytoplankton biomass in Novo Ilje 1 sample from 2003 was 2.6 x 10**8 cubic micrometer/l, and in 2004 sample was 1.09 x 10**8 cubic micrometer/l. Phytoplankton biomass in Novo Ilje 2 sample in 2003 was 3.06 x 10**8 cubic micrometer/l, and in 2004 sample was 1.62 x 10**8 cubic micrometer/l.

The puddles Novo Ilje 1 and Novo Ilje 2 are aquatic ecosystems periodically filled with moderate salt and alkaline water. In 2003 and 2004 quantitative analysis show the Euglenophyta domination. Trachelomonas taxa are the most common. The algae in planktonic communities are the most numerous in both puddles in researched years.

The salt pond Velika Slatina is the old meander of the river Tamis (Serbia). The ecosystem is periodically fill with moderate salt water. Phytoplankton production was 10 times bigger in 2003 than 2006. Ecological conditions were unfavourable for development of phytoplankton community. Diatoms show as the most abundant component in 2003, but euglenoids were in 2006, when bloom of Gloeotrichia natans f. bucharica Kissel was recorded. Results of biomass analysis also show dominant role of diatoms in 2003 and euglenoids in 2006.

Quality of irrigation water taken from three wells located at Rimski Sancevi near Novi Sad, Serbia, has been monitored for three years. The obtained results showed that the samples from the three wells had a relatively uniform quality. We are dealing with a mineralized water which may increase the salinity of poorly drained soil but it cannot cause soil alkalization because of low sodium levels. In view of the above, it is recommended to periodically check not only irrigation water quality but also soil salinity level.

The puddles Slatina and Pecena Slatina are the old meanders of the river Tamis. These ecosystems are periodicity fill with moderate salt and high alkaline water. The paper gives a review of qualitative and quantitative analysis of the algal compositions. Cyanoprokaryota and Euglenophyta are more common. All investigated parameters like compositions of lagal communities, their abundace, biomass and chlorphyll-a showed a high level of nature eutriphication in these ecosystems.