The Relationship between Primary Production and Respiration in the Photic Zone of the Great Mazurian Lakes (GMLS), in Relation to Trophic Conditions, Plankton Composition and Other Ecological Factors

ABSTRACT The relation of primary production to respiration and dependence of both processes on various environmental factors were investigated in the surface waters of lakes of The Great Mazurian Lake System (GMLS) during summer seasons 2009–2011. Primary production and extracellular release was determined by 14C method, respiration (dark oxygen consumption) - by Winkler's method. Collected results allow to conclude that: (i) in all studied lakes primary production was primarily cyanobacterial, although in mesotrophic ones participation of eukaryotic phytoplankton in light CO2 fixation was more pronounced; (ii) in mesotrophic part of GMLS primary production was limited alternately by N and P availability and less dependent on N and P regeneration processes, whereas in southern, eutrophic lakes it was primarily fueled by regeneration of biogenic substances from organic compounds and strongly limited by N resources; (iii) although in photic zone of whole GMLS respiration was dominated by heterotrophic bacte...