Testing responses of bacterial communities to environmental change using whole ecosystem manipulation experiments Metagenome

Disturbances are an important factor determining the diversity, composition and functioning of communities, however knowledge about how natural bacterial communities are affected by disturbances is sparse. We performed a whole ecosystem manipulation experiment with rock pools to test for the effects of salinity pulses of different intensities on the resistance and resilience of bacterial communities. Moreover, we aimed to identify the importance of regional processes such as dispersal and colonization for community recovery. After sampling for initial community and environmental conditions salt was added to the selected freshwater rock pools at 3, 6 or 12 ppm and approximately two days later they were sampled again to test for resistance. Following, the pools were filled-up by rainfall and then sampled once more to address the degree of resilience of the communities. During the latter period we placed out air and rain traps in the area to capture dispersing cells. Bacterial community composition was estimated based on 454-sequencing analysis of the 16S rRNA gene and community functions such as respiration and carbon substrate utilization rate (CSUR) were measured.