Biology subjects

Marmen, S.

Publications and source records attributed to Marmen, S..

3 recordsLinked to original sources

bioRxiv2023

Tar patties are hotspots of hydrocarbon turnover and nitrogen fixation during a nearshore pollution event in the oligotrophic southeastern Mediterranean Sea

Weathered oil, that is, tar, forms hotspots of hydrocarbon degradation by complex biota in marine environment. Here, we used marker gene sequencing and metagenomics to characterize the communities of bacteria, archaea and eukaryotes that colonized tar patties and control samples (wood, plastic), collected in the littoral following an offshore spill in the warm, oligotrophic southeastern Mediterranean Sea (SEMS). We show aerobic and anaerobic hydrocarbon catabolism niches on tar interior and exterior, linking carbon, sulfur and nitrogen cycles. Alongside aromatics and larger alkanes, short-chain alkanes appear to fuel dominant populations, both the aerobic clade UBA5335 (Macondimonas), anaerobic Syntropharchaeales, and facultative Mycobacteriales. Most key organisms, including the hydrocarbon degraders and cyanobacteria, have the potential to fix dinitrogen, potentially alleviating the nitrogen limitation of hydrocarbon degradation in the SEMS. We highlight the complexity of these tar-associated communities, where bacteria, archaea and eukaryotes co-exist, exchanging metabolites and competing for resources and space. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=68 SRC="FIGDIR/small/546273v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@7ff1eborg.highwire.dtl.DTLVardef@1e39012org.highwire.dtl.DTLVardef@107c307org.highwire.dtl.DTLVardef@95073f_HPS_FORMAT_FIGEXP M_FIG C_FIG

ecology↗

bioRxiv2021

Seasonal dynamics are the major driver of microbial diversity and composition in intensive freshwater aquaculture

Aquaculture facilities such as fishponds are one of the most anthropogenically impacted freshwater ecosystems. The high fish biomass reared in aquaculture is associated with an intensive input into the water of fish-feed and fish excrements. This nutrients load may affect the microbial community in the water, which in turn can impact the fish health. To determine to what extent aquaculture practices and natural seasonal cycles affect the microbial populations, we characterized the microbiome of an inter-connected aquaculture system at monthly resolution, over three years. The system comprised two fishponds, where fish are grown, and a "control" operational water reservoir in which fish are not actively stocked. Clear natural seasonal cycles of temperature and inorganic nutrients concentration, as well as recurring cyanobacterial blooms during summer, were observed in both the fishponds and the reservoir. The structure of the aquatic bacterial communities in the system, characterized using 16S rRNA sequencing, was explained primarily by the natural seasonality, whereas aquaculture-related parameters had only a minor explanatory power. However, the cyanobacterial blooms were characterized by different cyanobacterial clades dominating at each fishpond, possibly in response to distinct nitrogen and phosphate ratios. In turn, nutrient ratios may have been by the magnitude of fish feed input. Taken together, our results show that, even in strongly anthropogenically impacted aquatic ecosystems, the structure of bacterial communities is mainly driven by the natural seasonality, with more subtle effects if aquaculture-related factors. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=114 SRC="FIGDIR/small/433039v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@154d693org.highwire.dtl.DTLVardef@d35ae9org.highwire.dtl.DTLVardef@1f5a7a2org.highwire.dtl.DTLVardef@d07fbc_HPS_FORMAT_FIGEXP M_FIG C_FIG HighlightsO_LIWe present three years of monthly microbiome data from an aquaculture facility. C_LIO_LIThe microbiome changes seasonally, likely driven by temperature and rainwater runoff. C_LIO_LISummer blooms of toxin-producing cyanobacteria are repeatedly observed. C_LIO_LIFish food may impact microbiome through changes in nutrient ratios. C_LI

ecology↗

bioRxiv2018

The role of land use types and water chemical properties in structuring the microbiome of a connected lakes system

Lakes and other freshwater bodies are intimately connected to the surrounding land, yet to what extent land-use affects the quality of freshwater and the microbial communities living in various freshwater environments is largely unknown. We address this question through an analysis of the land use surrounding 46 inter-connected lakes located within 7 different drainage basins in northern Germany, and the microbiomes of these lakes during early summer. Lake microbiome structure was not determined by the specific drainage basin or by basin size, and bacterial distribution did not seem to be limited by distance. Instead, land use within the drainage basin could predict, to some extent, NO2+NO3 concentrations in the water, which (together with temperature, chlorophyll a and total phosphorus) affected water microbiome structure. Land use directly surrounding the water bodies, however, had little observable effects on water quality or the microbiome. Several microbial lineages, including environmentally important Cyanobacteria and Verrucomicrobia, were differentially partitioned between the lakes. As the amount of available data on land use (e.g. from remote sensing) increases, identifying relationships between land use, aquatic microbial communities and their effect on water quality will be important to better manage freshwater resources worldwide, e.g. by systemically identifying water bodies prone to ecological changes or the presence of harmful organisms.

microbiology↗