Eva-Maria Zetsche

Ludwig-Maximilians-University of Munich | LMU · Unit for Research Funding

Diatom aggregates constitute a significant fraction of the particle flux from the euphotic zone into the mesopelagic ocean as part of the ocean's biological carbon pump. Modeling studies of their exchange processes with the surrounding water usually assume spherical shape and that aggregates are impermeable to flow. Using particle image velocimetry...

Cable bacteria are multicellular, filamentous microorganisms that are capable of transporting electrons over centimeter-scale distances. Although recently discovered, these bacteria appear to be widely present in the seafloor, and when active they exert a strong imprint on the local geochemistry. In particular, their electrogenic metabolism induces...

Almost a century ago Redfield discovered a relatively constant ratio between carbon, nitrogen, and phosphorus in particulate organic matter, and nitrogen and phosphorus of dissolved nutrients in seawater. Since then, the riverine export of nitrogen to the ocean has increased 20‐fold. High abundance of resting stages in sediment layers dated more th...

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Cable bacteria are long, multicellular micro-organisms that are capable of transporting electrons from cell to cell along the longitudinal axis of their centimeter-long filaments. The conductive structures that mediate this long-distance electron transport are thought to be located in the cell envelope. Therefore, this study examines in detail the...

FIB-SEM data of filament BF2.

Cable bacteria are multicellular, filamentous microorganisms that are capable of transporting electrons over centimeter-scale distances. Although recently discovered, these bacteria appear to be widely present in the seafloor, and when active, they exert a strong imprint on the local geochemistry. In particular, their electrogenic metabolism induce...

The ability to quantify vital aquatic organisms in the 2–50 µm size range was compared between five different flow cytometers and several different microscopes. Counts of calibration beads, algal monocultures of different sizes as well as organisms in a Wadden Sea sample were compared. Flow cytometers and microscopes delivered different bead concen...

Particles of all origins (biogenic, lithogenic, as well as anthropogenic) are fundamental components of the coastal ocean and are re-distributed by a wide variety of transport processes at both horizontal and vertical scales. Suspended particles can act as vehicles, as well as carbon and nutrient sources, for microorganisms and zooplankton before e...

Recently, long filamentous bacteria have been reported conducting electrons over centimetre distances in marine sediments. These so-called cable bacteria perform an electrogenic form of sulfur oxidation, whereby long-distance electron transport links sulfide oxidation in deeper sediment horizons to oxygen reduction in the upper millimetres of the s...

Recently, long filamentous bacteria have been reported to conduct electrons over centimetre distances in marine sediments. These so-called cable bacteria perform a novel "electrogenic" form of sulfur oxidation, whereby long-distance electron transport links sulfide oxidation in deeper sediment horizons to oxygen reduction in the upper millimetres o...

Benthic algae or microphytobenthos (MPB) in intertidal flats play an important role in the sediment and overlying water ecosystems. We hypothesize that there are effects of sediment texture on the vertical distribution of MPB using chlorophyll a (chl a) as a proxy for MPB biomass and present results over a 2.5-year period. Four sites were sampled m...

Lophelia pertusa is the dominant reef-building organism of cold-water coral reefs, and is known to produce significant amounts of mucus, which could involve an important metabolic cost. Mucus is involved in particle removal and feeding processes, yet the triggers and dynamics of mucus production are currently still poorly described because the exis...

Movement of particle-laden mucus strings. Activated charcoal particles entrapped in mucus strings are moved along the thecal walls of Lophelia pertusa from the mouth area (upper edge) towards the lower parts and eventually base of the polyp (lower edge). (Video was captured at 1 frame s-1 and is shown at 2x speed). (MP4)

Cilia along tentacles remove particles. The movement of (activated charcoal) particles along the tentacles of a Lophelia pertusa polyp is always towards the tips of the tentacles. (Video was captured at 1 frame s-1 and is shown at 2x speed). (MP4)

Mucus release associated with the digestion of the shrimp nauplius Artemia salina by Lophelia pertusa. First the light intensity information is displayed before the phase information is shown. In the latter, lighter areas clearly depict mucoid substances being released from the mouth area located in the central part of the image. The polyp shown co...

Vortical movement of particle strings. Along the polyp surfaces particle strings were observed to follow circular motions on several occasions, here exemplified by one such incident. (Video was captured at 1 frame s-1 and is shown at 4x speed). (MP4)

Recent advances in optical components, computational hardware and image analysis algorithms have led to the development of a powerful new imaging tool, digital holographic microscopy (DHM). So far, DHM has been predominantly applied in the life sciences and medical research, and here, we evaluate the potential of DHM within a marine context, i.e. f...

Recently, a novel mode of sulphur oxidation was described in marine sediments, in which sulphide oxidation in deeper anoxic layers was electrically coupled to oxygen reduction at the sediment surface. Subsequent experimental evidence identified that long filamentous bacteria belonging to the family Desulfobulbaceae likely mediated the electron tran...

Traditional taxonomic identification of planktonic organisms is based on light microscopy, which is both time-consuming and tedious. In response, novel ways of automated (machine) identification, such as flow cytometry, have been investigated over the last two decades. To improve the taxonomic resolution of particle analysis, recent developments ha...

The rapid and efficient analysis of plankton samples (e.g. enumeration, identification, biomass determination) has been an important driver for recent technological developments in (semi-) automated analysis and imaging instruments. Most focus has been on identification and abundance estimates, while less attention has been given to viability, i.e....

Rapid organic matter turnover is driven by advective transport processes in sandy permeable sediments, allowing them to act as biocatalytic filters. This filtering capacity is largely defined by the permeability of the sediment, which describes the flow of water through a porous medium. However, little is known about the temporal variability of san...

While it has been widely accepted that numerous coral reefs, particularly in the Caribbean, have undergone a transition from coral-to-algal dominated communities, the reasons for this are still subject of an on-going debate. Apart from effects of reduced herbivory and nutrient enrichment, coral cover decline from bleaching, diseases and other physi...