A5045891093- Marine and coastal ecosystems
- Microbial Community Ecology and Physiology
- Methane Hydrates and Related Phenomena
- Marine Biology and Ecology Research
- Wastewater Treatment and Nitrogen Removal
- Coastal wetland ecosystem dynamics
- Geology and Paleoclimatology Research
- Oceanographic and Atmospheric Processes
- Coral and Marine Ecosystems Studies
- Ocean Acidification Effects and Responses
- Marine and coastal plant biology
- Groundwater and Isotope Geochemistry
- Marine and environmental studies
- Coastal and Marine Dynamics
- Protist diversity and phylogeny
- Analytical Chemistry and Sensors
- Groundwater flow and contamination studies
- Genomics and Phylogenetic Studies
- Marine Bivalve and Aquaculture Studies
- Soil and Water Nutrient Dynamics
- Nematode management and characterization studies
- Hydrology and Sediment Transport Processes
- Atmospheric and Environmental Gas Dynamics
- Optical Imaging and Spectroscopy Techniques
- CO2 Sequestration and Geologic Interactions
Max Planck Institute for Marine Microbiology
2016-2025
Leibniz Institute for Baltic Sea Research
2024-2025
University of Bremen
2019-2022
Leibniz Centre for Tropical Marine Research
2020
Max Planck Society
2013-2019
Marine coastlines colonized by seagrasses are a net source of methane to the atmosphere. However, emissions from these environments still poorly constrained, and underlying processes responsible microorganisms remain largely unknown. Here, we investigated turnover in seagrass meadows
Abstract Observations of waves, setup, and wave-driven mean flows were made on a steep coral forereef its associated lagoonal system the north shore Moorea, French Polynesia. Despite complex geometry forereef, wave amplitudes that are nearly equal to water depth, linear theory showed very good agreement with data. Measurements across reef illustrate importance including both transport (owing Stokes drift), as well Eulerian when computing fluxes over reef. Finally, observed setup closely...
Abstract We investigated microbial pathways of nitrogen transformation in highly permeable sediments from the German Bight (South‐East North Sea) by incubating sediment cores percolated with 15 N‐labeled substrates under near situ conditions. In incubations added , production occurred while was oxic, indicating ammonia oxidation. Similarly, during indicated nitrite Taken together these findings provide direct evidence high nitrification rates within sands. The N‐N 2 on addition revealed...
Summary The first interaction of water column‐derived organic matter with benthic microbial communities takes place in surface sediments which are acting as biological filters catalyzing central steps elemental cycling. Here we analyzed the bacterial diversity and community structure sediment top layers at seven sites North Sea where properties ranged from coarse‐grained highly permeable to fine‐grained impermeable. Bacterial were richer, more even significantly different bottom waters...
Abstract Symbiotic N 2 -fixing microorganisms have a crucial role in the assimilation of nitrogen by eukaryotes nitrogen-limited environments 1–3 . Particularly among land plants, symbionts occur variety distantly related plant lineages and often involve an intimate association between host symbiont 2,4 Descriptions such symbioses are lacking for seagrasses, which evolved around 100 million years ago from terrestrial flowering plants that migrated back to sea 5 Here we describe symbiont, ‘...
Abstract Mitochondria are specialized eukaryotic organelles that have a dedicated function in oxygen respiration and energy production. They evolved about 2 billion years ago from free-living bacterial ancestor (probably an alphaproteobacterium), process known as endosymbiosis 1,2 . Many unicellular eukaryotes since adapted to life anoxic habitats their mitochondria undergone further reductive evolution 3 As result, obligate anaerobic with mitochondrial remnants derive mostly fermentation 4...
Seagrasses are among the most efficient sinks of carbon dioxide on Earth. While sequestration in terrestrial plants is linked to microorganisms living their soils, interactions seagrasses with rhizospheres poorly understood. Here, we show that seagrass, Posidonia oceanica excretes sugars, mainly sucrose, into its rhizosphere. These sugars accumulate µM concentrations-nearly 80 times higher than previously observed marine environments. This finding unexpected as readily consumed by...
Abstract Seawater infiltration into the permeable sands of beach aquifers creates a high input biogeochemical reactants driven by tides and waves. The upper sand layer acts as filter, retaining particulate organic matter (POM), which is degraded bacteria under predominantly oxic conditions. seasonal variation seawater POM oxygen (O 2 ) entering zone, combined with filtration efficiency highly morphodynamic layer, determines turnover subsequent redox gradients along porewater flowpaths. We...
Abstract Large areas of the oceanic shelf are composed sandy sediments through which reactive solutes transported via porewater advection fueling active microbial communities. The advective oxygen transport in permeable sands North Sea was investigated under situ conditions using a new benthic observatory to assess dynamic interaction hydrodynamics, sediment morphodynamics, and penetration depth. During 16 deployments, concurrent measurement current velocity, topography, concentration were...
Abstract Permeable sediments are found wide spread in river beds and on continental shelves. The transport of these is forced by bottom water currents leads to the formation bedforms such as ripples dunes. flow across results pressure gradients that drive pore within permeable sediment enhance supply reactive substrates for biogeochemical processes. This transport‐reaction system has been extensively studied case stationary bedforms, whereas bedform migration—the most ubiquitous form...
Submarine groundwater discharge (SGD) is a ubiquitous source of meteoric fresh and recirculating seawater to the coastal ocean. Due hidden distribution SGD, as well hydraulic- stratigraphy-driven spatial temporal heterogeneities, one biggest challenges date correct assessment SGD-driven constituent fluxes. Here, we present results from 3-dimensional seasonal sampling campaign shallow subterranean estuary in high-energy, meso-tidal beach, Spiekeroog Island, Northern Germany. We determined...
Abstract Anaerobic oxidation of ammonium (anammox) in oxygen minimum zones (OMZs) is a major pathway oceanic nitrogen loss. Ammonium released from sinking particles has been suggested to fuel this process. During cruises the Peruvian OMZ April–June 2017 we found that anammox rates are strongly correlated with volume small (128–512 µm), even though bacteria were not directly associated particles. This suggests relationship between and related by remineralization. To investigate this, release...
A series of multibeam bathymetry surveys revealed the emergence a large pockmark field in southeastern North Sea. Covering an area around 915 km2, up to 1,200 pockmarks per square kilometer have been identified. The time can be confined 3 months autumn 2015, suggesting very dynamic genesis. gas source and trigger for simultaneous outbreak remain speculative. Subseafloor structures high methane concentrations 30 μmol/l sediment pore water samples suggest shallow biogenic from decomposition...
Sandy sediments cover 50-60% of the continental shelves and are highly efficient bioreactors in which organic carbon is remineralized inorganic nitrogen reduced to N2. As such they seem play an important role, buffering open ocean from anthropogenic inputs likely remineralizing vast amounts matter formed productive surface waters. To date however, little known about interrelation between porewater transport, grain properties microbial colonization consequences for remineralization rates...
Abstract. Marine aggregates are the vector for biogenically bound carbon and nutrients from euphotic zone to interior of oceans. To improve representation this biological pump in global biogeochemical HAMburg Ocean Carbon Cycle (HAMOCC) model, we implemented a novel Microstructure, Multiscale, Mechanistic, Aggregates Global (M4AGO) sinking scheme. M4AGO explicitly represents size, microstructure, heterogeneous composition, density porosity ties ballasting mineral particulate organic (POC)...
From individual cells to whole organisms, O2 transport unfolds across micrometer- millimeter-length scales and can change within milliseconds in response fluid flows organismal behavior. The spatiotemporal complexity of these processes makes the accurate assessment dynamics via currently available methods difficult or unreliable. Here, we present "sensPIV," a method simultaneously measure concentrations flow fields. By tracking O2-sensitive microparticles using imaging technologies that...
Most tropical corals live in symbiosis with Symbiodiniaceae algae whose photosynthetic production of oxygen (O2) may lead to excess O2 the diffusive boundary layer (DBL) above coral surface. When flow is low, cilia-induced mixing DBL vital remove and prevent oxidative stress that bleaching mortality. Here, we combined particle image velocimetry using O2-sensitive nanoparticles (sensPIV) chlorophyll (Chla)-sensitive hyperspectral imaging visualize microscale distribution dynamics ciliary...
Abstract The exchange of metabolites between environment and coral tissue depends on the flux across diffusive boundary layer (DBL) surrounding tissue. Cilia covering have been shown to create vortices that enhance mixing in DBL stagnant water. To study role cilia under simulated ambient currents, we designed a new light-sheet microscopy based flow chamber setup. Microparticle velocimetry was combined with high-resolution oxygen profiling Porites lutea varying current light conditions...
Abstract During seawater circulation in permeable intertidal sands, organic matter degradation alters the composition of percolating fluids and remineralization products discharge into surficial waters. Concurrently, coastal nutrient change seasonally due to variations pelagic productivity. To assess seasonal changes zone a high energy beach (Spiekeroog Island, southern North Sea, Germany), we analyzed shallow pore waters for major redox constituents (oxygen [O 2 ], manganese [Mn], iron...
Microbial biomass is a key parameter needed for the quantification of microbial turnover rates and their contribution to biogeochemical element cycles. However, estimates rely on empirically derived mass-to-volume relationships, large discrepancies exist between available empirical conversion factors. Here we report significant nonlinear relationship carbon mass cell volume ([Formula: see text]; [Formula: text]) based direct mass, volume, elemental composition measurements 12 prokaryotic...
Summary Coastal oceans receive large amounts of anthropogenic fixed nitrogen (N), most which is denitrified in the sediment before reaching open ocean. Sandy sediments, are common coastal regions, seem to play an important role catalysing this N‐loss. Permeable sediments characterized by advective porewater transport, supplies high fluxes organic matter into sediment, but also leads fluctuations oxygen and nitrate concentrations. Little known about how denitrifying communities these adapted...