Dinamika fitoplanktona i fenomen cvetanja cijanobakterije Planktothrixs rubescens u akumulaciji Vrutci

Abstract

Akumulacije predstavljaju važan vodni resurs namenjen dugoročnom snabdevanju vodom za piće, ali uprkos tome ne postoji adekvatan plan njihove zaštite. Predmet ove doktorske disertacije jeste praćenje prostorne i vremenske dinamike fitoplanktona akumulacije Vrutci, sa posebnim osvrtom na dinamiku potencijalno toksične cijanobakterije Planktothrix rubescens. Analiza je obuhvatala utvrđivanje sastava, brojnosti i biomase fitoplanktona na tri lokaliteta (Vodozahvat, Nikolići i Omar) i duž vodenog stuba tokom perioda od decembra 2013. do decembra 2015. godine. Pored toga praćeni su i osnovni fizički i (bio)hemijski parametri, takođe po mesecima i po dubini. Osnovni cilj studije je bio prikaz prostorne i vremenske dinamike vrste P. rubescens, otkrivanje najznačajnijih parametara odgvornih za njenu proliferaciju u akumulaciji, kao i procena uticaja „cvetanja“ ove cijanobakterije na dinamiku ostalih članova fitoplanktonske zajednice. Najveća brojnost i biomasa P. rubescens zabeležene su u julu 2015. godine na 6 m dubine (963855 ćel/ml odnosno 30,23 mm3/l) na lokalitetu Vodozahvat. Rezultati su pokazali da su temperatura vode i stabilnost vodene kolone faktori koji u najvećoj meri određuju rast P. rubescens, kao i da ova cijanobakterija ima uticaj na dinamiku drugih algi i cijanobakterija. P. rubescens je tokom perioda stratifikacije formirala metalimnionski maksimum hlorofila a praćen maksimumom koncentracije kiseonika (supersaturacija). Takođe, rezultati su pokazali da rast P. rubescens nije bio toliko uslovljen koncentracijom ispitivanih nutrijenata, iako je akumulacija u proseku bila eutrofna. Neophodno je sprovođenje organizovanog monitoringa osnovnih parametara kvaliteta vode, kao i redovno praćenje vertikalne distribucije biomase P. rubescens u akumulaciji Vrutci.

Reservoirs represent an important water resource intended for long-term supply, but despite that, there is no adequate plan for their protection. The subject of this dissertation is the survey of spatial and temporal dynamics of phytoplankton of the Vrutci reservoir, with special reference to the dynamics of the cyanobacterium Planktothrix rubescens. The analysis included determining the composition, abundance and biomass of phytoplankton at three sites (Vodozahvat, Nikolići i Omar) and along the water column during the period from December 2013 to December 2015. In addition, the basic physical and (bio)chemical parameters were also monitored by months and by depth. The aim of the study was to review the spatial and temporal dynamics of P. rubescens, to discover the most important parameters of its blooming in the reservoir and to assess the impact of this cyanobacterium on other members of phytoplankton. The highest abundance and biomass of P. rubescens were recorded in July 2015 at a depth of 6 m (963,855 cells/ml and 30.23 mm3/l, respectively) at the Vodozahvat. The results showed that water temperature and water column stability are the factors that largely determine the growth of P. rubescens, and that this cyanobacterium has a great influence on the dynamics of other algae and cyanobacteria. P. rubescens formed a metalimnion maximum of chlorophyll a during the stratification period, followed by a maximum of oxygen concentration (supersaturation). Also, the results showed that the growth of P. rubescens was not so much conditioned by the concentration of the nutrients, although the reservoir was eutrophic on average. It is necessary to conduct organized monitoring of the basic parameters of water quality as well as regular monitoring of the vertical distribution of P. rubescens biomass in the Vrutci reservoir.