The aim of the study was to indicate the abiotic parameters of water and bottom sediments, which significantly affect the reproduction of Potamothrix hammoniensis in 9 shallow eutrophic lakes, of which 5 were dominated by macrophytes and 4 – by phytoplankton. Samples were collected once a month from January to December 2012. The percentage of Potamothrix hammoniensis individuals with a developed reproductive system varied in individual lakes and ranged from 14 to 72%. There was no correlation between the distinguished lake types and the proportion of sexually mature individuals. The reproductive activity was not observed in summer and early autumn. Among the measured parameters, the highest values of the Pearson correlation coefficient were found between the percentage of individuals with a developed reproductive system and the conductivity (r = 0.69; p < 0.001), pH (r = 0.51; p = 0.002) and the organic matter content in the sediments (r = −0.42; p = 0.012). It is worth noting that there was no correlation between the percentage of sexually mature specimens and the water temperature (r = −0.22, p = 0.204) and the oxygen concentration (r = −0.08; p = 0.648).
The paper is an overview of the Baltic Sea and its basin characteristic. The geographical location and climate and weather of the Baltic Sea region according to its zones and seasons were described. Moreover, the abiotic parameters of water such as salinity, oxygen concertation and temperature distribution in the water column were explained. Some of these characteristic parameters has influence on the critical infrastructure networks existed in the Baltic Sea region as well as the critical infrastructure objects activity has significant impact on these parameters changes and consequently the environmentally quality of the region. Finally, the Baltic Sea as the sensitive area is presented.
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