English (United Kingdom)

https://curated-unify.zendy.io/wp-json/zendy-region/v1/featured_content/oa?rat=en

https://curated-unify.zendy.io/wp-json/zendy-region/v1/highlighted_journal/

Global: Zendy Plus annual

Presents the access of premium content as premium feature

Premium Content

Presents the keyphrase highlighting as premium feature

Keyphrase Highlighting

Presents the summarisation as premium feature

Summarisation

Insights

Presents the pdf analysis as premium feature

PDF Analysis

Presents the zaia usage as premium feature

ZAIA

Global: Zendy Tools annual

Global: Zendy Free Plan

Global: Zendy Tools monthly

Global: Zendy Plus monthly

. Over the next decade, the Baltic Sea is predicted toundergo severe changes including decreased salinity due to alteredprecipitation related to climate changes. This will likely impact thedistribution and community composition of Baltic Sea dinitrogen-fixing (N2-fixing)microbes, among which heterocystous cyanobacteria are especially adaptedto low salinities and may expand to waters with currently higher salinity,including the Danish Strait and Kattegat, while other high-salinity-adaptedN2 fixers might decrease in abundance. In order to explore the impact of salinity on the distribution and activityof different diazotrophic clades, we followed the natural salinity gradientfrom the eastern Gotland and Bornholm basins through the Arkona Basin to theKiel Bight and combined N2 fixation rate measurements with a molecularanalysis of the diazotrophic community using the key functional marker genefor N2 fixation nifH, as well as the key functional marker genes anfD and vnfD,encoding for the two alternative nitrogenases. We detected N2 fixation rates between 0.7 and 6 nmol N L−1 d−1, and the diazotrophic community was dominated by the cyanobacteriumrelated to Nodularia spumigena and the small unicellular, cosmopolitan cyanobacterium UCYN-A.Nodularia was present in gene abundances between 8.07 × 105 and 1.6 × 107 copies L−1 in waters with salinities of 10 and below, while UCYN-Areached gene abundances of up to 4.5 × 107 copies L−1 in waterswith salinity above 10. Besides those two cyanobacterial diazotrophs, wefound several clades of proteobacterial N2 fixers and alternativenitrogenase genes associated with Rhodopseudomonas palustris, a purple non-sulfur bacterium. Based onprincipal component analysis (PCA), salinity was identified as the primaryparameter describing the diazotrophic distribution, while pH and temperaturedid not have a significant influence on the diazotrophic distribution. Whilethis statistical analysis will need to be explored in direct experiments, itgives an indication for the future development of diazotrophy in a fresheningBaltic Sea with UCYN-A retracting to more saline North Sea waters andheterocystous cyanobacteria expanding as salinity decreases.

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