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The acidification of the oceans could potentially alter marine plankton communities with consequences for ecosystem functioning. While several studies have investigated effects of ocean acidification on communities using traditional methods, few have used genetic analyses. Here, we use community barcoding to assess the impact of ocean acidification on the composition of a coastal plankton community in a large scale, in situ, long-term mesocosm experiment. High-throughput sequencing resulted in the identification of a wide range of planktonic taxa (Alveolata, Cryptophyta, Haptophyceae, Fungi, Metazoa, Hydrozoa, Rhizaria, Straminipila, Chlorophyta). Analyses based on predicted operational taxonomical units as well as taxonomical compositions revealed no differences between communities in high CO2 mesocosms (~ 760 μatm) and those exposed to present-day CO2 conditions. Observed shifts in the planktonic community composition were mainly related to seasonal changes in temperature and nutrients. Furthermore, based on our investigations, the elevated CO2 did not affect the intraspecific diversity of the most common mesozooplankter, the calanoid copepod Pseudocalanus acuspes. Nevertheless, accompanying studies found temporary effects attributed to a raise in CO2. Differences in taxa composition between the CO2 treatments could, however, only be observed in a specific period of the experiment. Based on our genetic investigations, no compositional long-term shifts of the plankton communities exposed to elevated CO2 conditions were observed. Thus, we conclude that the compositions of planktonic communities, especially those in coastal areas, remain rather unaffected by increased CO2.

The IVU32 is the world’s first in-vacuum APPLE II undulator currently under development at HZB. Magnetic characterisation and tuning of this short-period small-gap device will be carried out using measurements with an in-vacuum Hall probe bench and moving wire system, as well as with a pulsed wire measurement (PWM) setup. The PWM technique is an especially useful solution for measuring the magnetic field in limited undulator gaps, such as those found in in-vacuum and cryogenic devices. The pulsed wire system at HZB enables a complete characterization of the undulator magnetic field and provides a cost-efficient technique for fast and easy measurements. We present the state of development of the pulsed wire system at HZB and discuss the limitations of the method, for example, due to the specific wire properties that influence the error increase and thus measurement accuracy.

SESAME and a consortium of five Helmholtz Centers are designing and installing a state-of-the-art soft X-Ray undulator beamline at the SESAME light source in Amman, Jordan. Funding is provided by the Helmholtz Association over a four year project cycle that started in January 2019. This is an interim report covering the first 36 months of the project where the construction and installation has been almost completed and commissioning and characterization of the beamline is about to start. Additionally, seminars, workshops, and a training program are part of the project aimed at establishing a broad user community.