The microbial ecosystem of the air is rather complex and until today there is not much know about the microbial composition of this ecosystem. Current analysis showed that often bioaerosols have a similar bacteria community like the nearby ecosystems. The primary mechanism for sea-to-air transfer of bacteria is believed to be bursting of small bubbles at the ocean surface, which are primarily generated by whitecaps. These bubbles have to pass through the marine surface microlayer, which contains high concentration of microorganism and organic matter. It also has been shown that the compositions of the airborne communities underlie spatial fluctuations induced by meteorological conditions and vary during different periods of time (daily, weekly, monthly and seasonal). Brodie et al. (2007) revealed the consistent presence of bacterial families with pathogenic members in urban aerosols. Genetic relatives of selected agents of bioterrorism (e.g. Bacillus sp.) can be detected in the native airborne bacterial community. The microorganisms rise up due to the airstream and can have long sojourn time in the air up to several days in the atmosphere. This makes intercontinental transport for microorganism possible, which is a problem concerning pathogens. The duration of those particles staying up in the air is directly correlated with their size and weight. Bacteria with a size of 1.0-5.0 µm stay longer in the air then bigger particles, which drop down faster. Prospero et al. (2005) showed the transport of viable bacteria and fungi from Africa to the Caribbean with soil dust is possible. Also various other studies could proof bacterial transport over long distances. Therefore the composition and dynamics of these communities is of particular interest for security and needs further investigations.

Bioaerosol in the marine air above Helgoland will be the main focus of my Ph.D. research. The project is a co-operation with the Wehrwissenschaftliche Institut für Schutztechnologie – ABC Schutz (WIS) and financed by them. My aim for this Ph.D. is to use the excellent remote and exposed position of Helgoland to conduct an annual survey of the marine bioaerosols of the North Sea. And I am going to take samples during a trip on the research vessel “Heincke” around the Danish coastline. The daily taken samples of the marine air will be analyzed by culture independent molecular methods due to the estimation that only less than 1 % of the airborne bacteria are culturable.

The structure of the bacterial community will be analyzed by ARISA (Automated Ribosomal Intergenic Spacer Analyse). The enumeration of airborne bacteria will be performed by quantitative Real Time PCR (Q RT-PCR). The specific identification of the bacterial populations will be realized DHPLC followed by direct sequencing or by Clone-Libraries. The Method of choice has still to be decided after an evaluation period. All acquired data will be correlated with environmental variables as temperature, humidity, radiation and wind speed to look for possible correlations with number of particles and changes in bacterial communities with the help of multivariate statistics. The origin of the sampled air will be estimated by using air mass backward trajectory.

• Contract research: Wehrwissenschaftliches Institut für Schutztechnologien – ABC-Schutz (WIS)
• MARMIC PhD student