Diazotrophic cyanobacteria in planktonic food webs

Blooms of cyanobacteria are recurrent phenomena in coastal estuaries. Their maximum abundance coincides with the productive period zooplankton and pelagic fish. Experimental studies indicate that diazotrophic, i.e. dinitrogen (N2)-fixing cyanobacterial (taxonomic order Nostocales) blooms affect zooplankton, as well other phytoplankton. We used multidecadal monitoring data from one archipelago station (1992–2013) ten open sea stations (1979–2013) Baltic Sea to explore potential bottom-up connections between diazotrophic non-diazotrophic phyto- natural plankton communities. Random forest regression, combined linear regression analysis showed biomass (both non-diazotrophic) was barely connected any phytoplankton variables examined. Instead, physico-chemical (salinity, temperature, total phosphorus), spatial temporal variability seemed have more significant both variables. Zooplankton were also groups than (such chrysophytes, cryptophytes prymnesiophytes), had different groups, especially copepods. Overall, negative relationships taxa scarcer expected based on previous experimental studies.