Katarina Damjanovic "Coral-­‐associated bacterial communities in early coral life stages: transmission mode and scope for manipulation" PhD completion seminar

Seminar/Forum

Katarina Damjanovic "Coral-­‐associated bacterial communities in early coral life stages: transmission mode and scope for manipulation" PhD completion seminar

Supervisors: Prof. Madeleine van Oppen Prof. & Linda Blackall

Global  impacts  of  climate  change  and  other  anthropogenic  disturbances  are  causing  massive  declines in coral reef ecosystems. As reef-­‐forming scleractinian corals provide essential resources to  a  large  part  of  the  population,  their  degradation  has  severe  ecological  and  economic  consequences. Efforts are therefore urgently needed to assist coral adaptation to our rapidly changing  environment.  Within  this  scope,  favourably  adjusting  coral  associated  microbial  communities could greatly benefit the host, as microbial symbionts are known to play critical roles in  coral  health.  Probiotics  have  already  proven  efficient  in  other  organisms  such  as  plants  to  increase crop yields, or humans to treat various bowel conditions. The successful application of probiotics in corals is contingent on the feasibility to manipulate the coral microbiome. Moreover, understanding  how  corals  acquire  and  maintain  their  microbial  communities  is  required  to  evaluate whether probiotics could be retained across generations.

In  this  study,  I  investigated  the  transmission  mode  of  coral-­‐associated  bacteria  using  16S  rRNA  gene metabarcoding and fluorescence in situ hybridisation microscopy to gain insights into the stability and acquisition patterns of the coral prokaryotic microbiome. While patterns of vertical transmission were present in a brooder, no evidence of direct vertical transmission was observed in a broadcast spawner. Here, early coral life stages successively associated with different bacterial communities,  probably  selected  from  the  environmental  pool.  However,  parental  colonies  may  drive the transfer of certain bacteria by releasing them in the water column upon spawning and through  the  mucus  layer  coating  the  gametes.  In  addition,  I  explored  the  possibility  of  manipulating coral-­‐associated bacterial communities by exposing coral recruits to whole microbiomes as well as to a cocktail comprising a small number of bacterial pure cultures. In the latter  approach,  the  bacterial  strains  present  in  the  inoculation  consortium  were  enriched  in  inoculated recruits of the two coral species used in the experiment. Nevertheless, the two species of coral recruits developed a distinct microbiome despite being reared in the same aquaria and being inoculated with the same cocktail, which highlights a role of host factors in shaping bacterial community  composition.  These  results  support  proof-­‐of-­‐concept  for  the  feasibility  of  coral  microbiome manipulation as a first step towards developing probiotics for coral reef restoration.

Presenter

  •  Katarina Damjanovic
    Katarina Damjanovic,