Culturing facilities
We have 4 culturing facilities of which the room temperatures can be regulated individually and kept at a constant temperature. These rooms are used for cultivating the so-called stock cultures and doing experiments. For the moment two culturing rooms are run at 2°C and two at 15°C and 25°C, respectively.
Coulter Counter
The Coulter Counter is an instrument for counting particles in an electrically conducting fluid. Originally developed for analyzing blood cells this method also allows the determination of unicellular algae in a culturing medium with respect to number and size.
For one measurement with our Coulter Counter (Multisizer3, Beckmann Coulter) approx. 10 ml of culturing medium is needed.
Alkalinity
Alkalinity is an important parameter in the marine carbonate system. It is determined via titration. For this we run a TW Alpha Plus device from SI Analytics. The instrument has 21 sample holders. A minimum volume of 60 ml is needed for a duplicate determination.
Dissolved Inorganic Carbon (DIC)
Using "Continuous Flow Analyzers" (CFAs) manufactured by Seal, we are able to assess the concentrations of dissolved inorganic carbon (DIC) in sewater in a high throughput fashion. We also provide these analytics to our colleagues from other AWI sections.
Nutrient analysis
For analyzing nutrients we use a Quaatro 39 Autoanalyzer from Seal Analytics. The device has 39 pump tube positions. A sample volume of approx. 6 ml is needed for one measurement determining ammonium, nitrite, nitrate, phosphate, and silicate, simultaneously.
High-pressure aquaria for the cultivation of deep-sea foraminifers
We work with high-pressure aquaria of 3L, 10mL and 0.3mL to simulate deep sea conditions for the cultivation of deep-dwelling foraminifers. The smaller volume aquaria allow a visual connection with the confocal and as well as our Axiozoom microscope. For the microscope observations, special cooling-tables, ventilations and illumination equipment was customized.
Membrane-Inlet Mass Spectrometer (MIMS) for the monitoring of gas exchange processes of phytoplankton on the cellular level and in real-time. Our MIMS system consists of a custom-made, temperature-stabilized cuvette and inlet system combined with a sector field multicollector mass spectrometer (IsoPrime). Dissolved gas molecules like CO2 or O2 permeate through the membrane, are ionised and detected only seconds later in the mass spectrometer. The advantage of this approach is that several processes, e.g. cellular fluxes of carbon, oxygen and electrons, can be observed and quantified simultaneously.
A second, ship-going Membrane-inlet mass spectrometer (MIMS) was built for field and ship-based applications on expeditions. Being designed for standalone operation, the system has its own energy-backup, gas compressor and low-temperature (-100°C) generator, requiring only common 220V electricity input. This system is based on a quadrupole mass spectrometer (Pfeiffer) and was optimized for continuous measurements of CO2, O2 and argon. With this approach, also community production can be assessed with high temporal and spatial resolution.
Chlorophyll a-fluorescence based approaches such as Fast Repetition Rate Fluorometry (FRRF) provide a unique analytical insight into photosynthesis. Our FastOcean-FRRF (Chelsea Industries) is used to characterize changes in electron transport efficiencies as well as for the estimation of energy transfer efficiencies from photochemistry to (14C-based) biomass buildup. Furthermore, the FRRF technique derives the functional absorption cross section, the extent of excitation transfer between PSII reactions centres (connectivity factor), the yield of charge separation (efficiency of energy capture), and kinetics of photosynthetic electron transport. In addition to these, we operate a Fluorescence-Induction Relaxation system (FIRe; Satlantic) that is directly connected to the MIMS. This allows real-time assessment of both ‘ends of photosynthesis’, so that electron transport can be directly compared with oxygen and carbon fluxes.
For our research we need to culture microalgae in appropriate vessels that suffice high demands regarding optimal volume, irrandiance, mixing, aeration etc.. Therefore, we operate several different designs of incubators serving different needs, e.g. open- and closed-system dilute batch approaches or chemostats. To supply our laboratories with aeration, we constructed a gas-mixing system that creates air with CO2 partial pressures adjusted to our needs.
For measuring particulate C and N including their isotopic signatures in samples, we use an ANCA-SL 20–20 (Sercon) mass spectrometer. Next to determining the elemental quotas, stoichiometry and fractionation, MS measurements are also used for tracer studies with stable isotopes (e.g. 13C, 15N).
With the help of flow cytometry (Accuri C6, BD Biosciences), we can investigate the composition of smaller fractions of natural or experimental phytoplankton assemblages, which are otherwise difficult to resolve. Furthermore, the flow cytometer is a powerful tool for the enumeration and physiological characterization of single-celled phytoplankton species, e.g. after staining with specific dyes.
Our section runs a fully equipped wet-chemistry laboratory. Here we are able to determine properties of seawater like Total Alkalinity, Dissolved inorganic carbon (DIC) and pH with high precision and accuracy using automated burette systems, colorimetric DIC analyzer and a spectrophotometer for most exact pH measurements. Nutrient analyzers and procedures to determine biogenic silica are also available for our research.
In support of AWI´s FRAM Ocean observatory, we increasingly operate submersed in-situ sensors to measure year-long profiles and time series. These sensors are less precise compared to lab-based chemical analyses and thus require comparisons with conventionally analyzed water samples. Besides new innovations like ADCPs that monitor currents based on the movement of particles in the water column, we also apply sensors like CTDs to obtain conductivity and temperature data. To get information about biological and chemical parameters, we deploy pH, pCO2 and nitrate sensors. A water sampler deployed close to these sensors provides up to 48 reference water samples for sensor calibration and further chemical analyses back in the institute.