Description:    A study of the transformation of Lake Ladoga ecosystem in 1996–2005 shows that a decrease in the phosphorus load after 1995 has not cause a decrease in lake ecosystem productivity. Mathematical modeling provided an explanation of the observed phenomenon, thus justifying limnologists’ hypothesis that phosphorus turnover within a water body accelerates with increasing abundance of bacterioplankton and aquatic fungi. Computational experiments have shown that the additional amount of phosphorus that is required for maintaining phytoplankton productivity is additionally released by destructors (bacterioplankton and aquatic fungi) from detritus and organic matter dissolved in water. Content Type Journal Article Category Water Quality and Protection: Environmental Aspects Pages 806-817 DOI 10.1134/S0097807811060145 Authors L. A. Rukhovets, St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, ul. Chaikovskogo 1, St. Petersburg, 191187 Russia N. A. Petrova, Institute of Limnology, Russian Academy of Sciences, ul. Sevast’yanova 9, St. Petersburg, 196199 Russia V. V. Menshutkin, St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, ul. Chaikovskogo 1, St. Petersburg, 191187 Russia G. P. Astrakhantsev, St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, ul. Chaikovskogo 1, St. Petersburg, 191187 Russia T. R. Minina, St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, ul. Chaikovskogo 1, St. Petersburg, 191187 Russia V. N. Poloskov, St. Petersburg Institute for Economics and Mathematics, Russian Academy of Sciences, ul. Chaikovskogo 1, St. Petersburg, 191187 Russia T. N. Petrova, Institute of Limnology, Russian Academy of Sciences, ul. Sevast’yanova 9, St. Petersburg, 196199 Russia O. M. Susareva, Institute of Limnology, Russian Academy of Sciences, ul. Sevast’yanova 9, St. Petersburg, 196199 Russia Journal Water Resources Online ISSN 1608-344X Print ISSN 0097-8078 Journal Volume Volume 38 Journal Issue Volume 38, Number 6