BOWLS Cruise Blog
Microbiology
June 25, 2014
45° 51' N 125° 09' W
 Whale bone on the lid of a recovered lander |
Coming from Germany with no experience about the Pacific Ocean, I was very excited to participate in the BOWLS cruise, having the chance to work on microbial processes in whalebones and wood substrate. Having dissected whales as a student (I was young and needed the money), I already had an idea of the rich flavor dead whales produce – and also on this cruise I would not be disappointed!
Just before the cruise I fell deeply in love with beef jerky. So I bought a decent stash for the two weeks at sea to come. But apparently, the cook’s stash of jerky was even greater than mine - heaven! Articulating a positive attitude to Germany, he nicknamed me „Schnitzel“. Hopefully, nobody else will pick it up. Instead, I like the way my US colleagues pronounce my name Stefan on the second syllable, as they make it sound very Italian.
-Got to fetch some jerky-
Ok. Now we will hit science.
 Stefan sawing a whale bone for microbes |
In addition to meio- (less than 1mm) and megafauna also microbial communities utilize available whale bones at the seafloor. As microbes are much more creative regarding metabolic pathways than animals, a whale bone provides valuable substrate and nutrition for various groups. The freshly sunken bone is immediately attacked by aerobic bacteria, oxidizing available carbon sources.
-Got to fetch some more jerky-
After initial degradation by this group, the oxygen concentration in and adjacent to the bone is usually strongly reduced. Now it is time for anaerobic microbes to step in. Among these, sulfate-reducing bacteria and methanogenic (methane-producing) archaea play a major role in anaerobic degradation of the organic components of the bone. During this stage the bone will change color, displaying black patches, due to produced sulfide precipitates with iron, a strong indicator for microbial sulfate reduction activity. Once the anaerobic sulfate reducing community is established, sulfur bacteria settle on the bone surface, oxidizing previously produced sulfide.
-Got to fetch even more jerky-
During the cruise I will be taking bone samples to constrain the anaerobic microbial turnover rates of sulfate reduction and methane production - I guess you do not find too many microbiologists working with sterilized bone saws. In addition, penetration depth into the bone by different microbial groups will be analyzed, including diagnostic microscopy and molecular analyses. The ultimate goal is to constrain the onset and speed of relevant microbial processes during early stage whale bone degradation.
Cheers,
Stefan Krause
GEOMAR Helmholtz Centre for Ocean Research Kiel
Last updated: 06/27/2014