The combined impact of low temperatures and shifting phosphorus availability on the competitive ability of cyanobacteria

In freshwater systems, cyanobacteria are strong competitors under enhanced temperature and eutrophic conditions. Understanding their adaptive and evolutionary potential to multiple environmental states allows us to accurately predict their response to future conditions. To better understand if the combined impacts of temperature and nutrient limitation could suppress the cyanobacterial blooms, a single strain of Microcystis aeruginosa was inoculated into natural phytoplankton communities with different nutrient conditions: oligotrophic, eutrophic and eutrophic with the addition of bentophos. We found that the use of the bentophos treatment causes significant differences in prokaryotic and eukaryotic communities. This resulted in reduced biodiversity among the eukaryotes and a decline in cyanobacterial abundance suggesting phosphorus limitation had a strong impact on the community structure. The low temperature during the experiment lead to the disappearance of M. aeruginosa in all treatments and gave other phytoplankton groups a competitive advantage leading to the dominance of the eukaryotic families that have diverse morphologies and nutritional modes. These results show cyanobacteria have a reduced competitive advantage under certain temperature and nutrient limiting conditions and therefore, controlling phosphorus concentrations could be a possible mitigation strategy for managing harmful cyanobacterial blooms in a future warmer climate

THE ANTHROPIC LAKES FROM THE HYDROGRAPHIC BASIN OF UPPER IALOMIŢA (ROMANIA)

The hydrographic basin of upper Ialomiţa has become an area of interest for hydrotechnicians beginning with the period between the two World Wars, due to its hydroenergetic potential estimated at around 1 500-2 000 KWh. In this sense, in time, a series of hydrotechnical arrangements have been made, behind which important water resources have gathered. In this geographical area, there are nine accumulation lakes (without taking into account the years when they were achieved), both on the main river and on its tributaries. They serve different purposes: to regulate the regime of the liquid flow in order to attenuate the high floods, water resource for downstream consumers, electric energy production etc