Stimulation of nitrogen-fixing cyanobacteria in a Baltic Sea plankton community by land-derived organic matter or iron addition
|Author(s)||Stolte Willem1, Balode Maija2, Carlsson Per3, Grzebyk Daniel4, 9, 10, Janson Sven1, Lips Inga5, Panosso Renata1, 6, Ward Clive J.7, 8, Graneli Edna1|
|Affiliation(s)||1 : Kalmar Univ, Dept Biol & Environm Sci, Kalmar, Sweden.
2 : Latvian State Univ, Inst Aquat Ecol, Riga, Latvia.
3 : Lund Univ, S-25108 Lund, Sweden.
4 : IFREMER, CNRS, Ctr Rech Marine & Aquaculture, F-17137 Lhoumeau, France.
5 : Tallinn Tech Univ, Marine Syst Inst, EE-200108 Tallinn, Estonia.
6 : Univ Fed Rio Grande do Norte, Dept Microbiol & Parasitol, BR-59072970 Natal, RN, Brazil.
7 : Univ Dundee, Div Environm & Appl Biol, Dundee DD1 4HQ, Scotland.
8 : Marine Resource Ctr, Barcaldine PA37 1SE, Argyll, Scotland.
9 : Rutgers State Univ, Inst Marine & Coastal Sci, New Brunswick, NJ 08901 USA.
|Source||Marine Ecology Progress Series (0171-8630) (Inter-Research), 2006-12 , Vol. 37 , P. 71-82|
|WOS© Times Cited||26|
|Keyword(s)||Mesocosm experiment, Humic acid, HMWDOM, High molecular weight dissolved organic matter, Iron, Nitrogen fixation, Cyanobacteria|
|Abstract||In the Baltic Sea, floating blooms of nitrogen-fixing cyanobacteria occur yearly during late summer. These blooms can sometimes be limited by iron. Due to extensive foresting around the Baltic Sea, iron is entering the Baltic Sea partly bound to dissolved organic material (DOM) via rivers. An experiment was performed in 300 1 laboratory mesocosms to test the hypothesis that riverine high-molecular weight dissolved organic matter (HMWDOM), extracted by tangential flow filtration > 1000 Da, stimulates the biomass of nitrogen-fixing cyanobacteria, by increasing the availability of iron. The addition of iron/EDTA and of DOM resulted in 5 to 10 times higher biomass of nitrogen-fixing cyanobacteria. Accordingly, higher primary production and particulate nitrogen concentration at the end of the experiment were observed in those treatments compared to the control. The removal of mesozooplankton grazers did not have a significant effect on the microphytoplankton biomass and species composition. Nodularia spumigena biomass was highest in the treatments receiving DOM, but addition of iron alone had no significant effect on this. N. spumigena was less positively affected by iron addition than Anabaena cf. inaequalis, suggesting that N, spumigena is a better competitor for iron. Separate microcosms comparing additions of iron, manganese and cobalt showed that iron was limiting for cyanobacterial biomass development. The results strongly suggest that iron bound to DOM can contribute to the iron demands of nitrogen-fixing cyanobacteria in the Baltic Sea.|