@unpublished{GrossartRiemannTang2013, author = {Grossart, Hans-Peter and Riemann, Lasse and Tang, Kam W.}, title = {Molecular and functional ecology of aquatic microbial symbionts}, series = {Frontiers in microbiology}, volume = {4}, journal = {Frontiers in microbiology}, number = {6125}, publisher = {Frontiers Research Foundation}, address = {Lausanne}, issn = {1664-302X}, doi = {10.3389/fmicb.2013.00059}, pages = {2}, year = {2013}, language = {en} } @article{TangBackhausRiemannetal.2019, author = {Tang, Kam W. and Backhaus, Liv and Riemann, Lasse and Koski, Marja and Grossart, Hans-Peter and Munk, Peter and Nielsen, Torkel Gissel}, title = {Copepod carcasses in the subtropical convergence zone of the Sargasso Sea}, series = {Journal of plankton research}, volume = {41}, journal = {Journal of plankton research}, number = {4}, publisher = {Oxford Univ. Press}, address = {Oxford}, issn = {0142-7873}, doi = {10.1093/plankt/fbz038}, pages = {549 -- 560}, year = {2019}, abstract = {The oligotrophic subtropical gyre covers a vast area of the Atlantic Ocean. Decades of time-series monitoring have generated detailed temporal information about zooplankton species and abundances at fixed locations within the gyre, but their live/dead status is often omitted, especially in the dynamic subtropical convergence zone (STCZ) where the water column stratification pattern can change considerably across the front as warm and cold water masses converge. We conducted a detailed survey in the North Atlantic STCZ and showed that over 85\% of the copepods were typically concentrated in the upper 200 m. Copepod carcasses were present in all samples and their proportional numerical abundances increased with depth, reaching up to 91\% at 300-400 m. Overall, 14-19\% of the copepods within the upper 200 m were carcasses. Shipboard experiments showed that during carcass decomposition, microbial respiration increased, and the bacterial community associated with the carcasses diverged from that in the ambient water. Combining field and experimental data, we estimated that decomposing copepod carcasses constitute a negligible oxygen sink in the STCZ, but sinking carcasses may represent an overlooked portion of the passive carbon sinking flux and should be incorporated in future studies of carbon flux in this area.}, language = {en} } @article{LundgreenJaspersTravingetal.2019, author = {Lundgreen, Regitze B. C. and Jaspers, Cornelia and Traving, Sachia J. and Ayala, Daniel J. and Lombard, Fabien and Grossart, Hans-Peter and Nielsen, Torkel G. and Munk, Peter and Riemann, Lasse}, title = {Eukaryotic and cyanobacterial communities associated with marine snow particles in the oligotrophic Sargasso Sea}, series = {Scientific reports}, volume = {9}, journal = {Scientific reports}, publisher = {Nature Publ. Group}, address = {London}, issn = {2045-2322}, doi = {10.1038/s41598-019-45146-7}, pages = {12}, year = {2019}, abstract = {Marine snow aggregates represent heterogeneous agglomerates of dead and living organic matter. Composition is decisive for their sinking rates, and thereby for carbon flux to the deep sea. For oligotrophic oceans, information on aggregate composition is particularly sparse. To address this, the taxonomic composition of aggregates collected from the subtropical and oligotrophic Sargasso Sea (Atlantic Ocean) was characterized by 16S and 18S rRNA gene sequencing. Taxonomy assignment was aided by a collection of the contemporary plankton community consisting of 75 morphologically and genetically identified plankton specimens. The diverse rRNA gene reads of marine snow aggregates, not considering Trichodesmium puffs, were dominated by copepods (52\%), cnidarians (21\%), radiolarians (11\%), and alveolates (8\%), with sporadic contributions by cyanobacteria, suggesting a different aggregate composition than in eutrophic regions. Composition linked significantly with sampling location but not to any measured environmental parameters or plankton biomass composition. Nevertheless, indicator and network analyses identified key roles of a few rare taxa. This points to complex regulation of aggregate composition, conceivably affected by the environment and plankton characteristics. The extent to which this has implications for particle densities, and consequently for sinking rates and carbon sequestration in oligotrophic waters, needs further interrogation.}, language = {en} }