Salinity as a key control on the diazotrophic community composition in the southern Baltic Sea

Over the next decade, the Baltic Sea is predicted to undergo severe changes including decreased salinity due to altered precipitation related to climate changes. This will likely impact the distribution and community composition of Baltic Sea dinitrogen-fixing (N.sub.2 -fixing) microbes, among which heterocystous cyanobacteria are especially adapted to low salinities and may expand to waters with currently higher salinity, including the Danish Strait and Kattegat, while other high-salinity-adapted N.sub.2 fixers might decrease in abundance.