caa a22 4500 445891831 CHVBK 20180317145619.0 cr unu---uuuuu 170323e20110201xx s 000 0 eng 10.1007/s10750-010-0410-9 doi (NATIONALLICENCE)springer-10.1007/s10750-010-0410-9 Long-term trends and regional differences of phytoplankton in large Finnish lakes [Elektronische Daten] [Lauri Arvola, Marko Järvinen, Tiina Tulonen] Major nutrients (N and P) and phytoplankton from 19 large lakes from southern (61°) to northern (69°) Finland were analyzed to detect long-term trends and regional differences. The data sets from June, July and August cover the period from the early 1980s to the present. Altogether >700 phytoplankton and >4000 N, P and Chl a results were used for the study. In 40% of the lakes, the total phosphorus (TP) concentration decreased significantly and in >25% of the lakes a significant reduction was found in the total nitrogen (TN) concentration. At the same time, the phytoplankton biomass declined only in 15% of the lakes and the long-term trends in chlorophyll a more often increased than decreased. A clear gradient from southern to northern Finland and western to eastern Finland was found in the phytoplankton biomass. During the study period, the biomasses of cyanobacteria and centrales (diatoms) decreased whilst there was an increase in the biomass of pennales (diatoms) in one-third of the lakes. The proportion of chlorophytes in the total biomass also increased in >20% of the study lakes. In southern and western Finland, the total biomass and the contribution of cyanobacteria were higher. Centrales made a higher contribution to the total biomass in the north. Pennales and chlorophytes were less abundant and chrysophytes more abundant in the east. Differences in the community composition reflected the gradients in the total nutrients, and particularly in TP. The observations support the assumed role of phosphorus as the key limiting nutrient in large Finnish lakes irrespective of lake′s location. The N:P ratio proved to be a poor predictor of cyanobacteria occurrence in the study lakes. Springer Science+Business Media B.V., 2010 Large lake nationallicence Phytoplankton nationallicence Nitrogen nationallicence Phosphorus nationallicence Long-term trend nationallicence Spatial gradient nationallicence Community composition nationallicence Chlorophyll nationallicence Arvola Lauri Lammi Biological Station, University of Helsinki, Helsinki, Finland aut Järvinen Marko Finnish Environment Institute, Helsinki, Finland aut Tulonen Tiina Lammi Biological Station, University of Helsinki, Helsinki, Finland aut Hydrobiologia Springer Netherlands 660/1(2011-02-01), 125-134 0018-8158 660:1<125 2011 660 10750 https://doi.org/10.1007/s10750-010-0410-9 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-010-0410-9 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Arvola Lauri Lammi Biological Station, University of Helsinki, Helsinki, Finland aut NATIONALLICENCE 700 1- Järvinen Marko Finnish Environment Institute, Helsinki, Finland aut NATIONALLICENCE 700 1- Tulonen Tiina Lammi Biological Station, University of Helsinki, Helsinki, Finland aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 660/1(2011-02-01), 125-134 0018-8158 660:1<125 2011 660 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer