Architecture of marine snow microbial communities

In the water column of the ocean, ubiquitous non-living particles occur, produced from polymeric sugars of decaying plankton appearing like snow flakes hence, they are coined marine snow. Marine snow has been known as a hotspot of microbial activity in the water column of the oceans with microbial abundances and activities up to three orders of magnitude higher, on a volume base, than in the surrounding waters. Marine snow is particularly abundant in the coastal Adriatic Sea. Consequently, microbial activity on marine snow in the Adriatic has been well studied, however, essentially only on the bulk activity level. In ARTEMIS, we will specifically focus on the community structure of marine snow-associated microbial communities during the successional stages of marine snow by combining modern molecular biology approaches within with metabolic rate measurements. The microspatial architecture of the marine snow-associated microbial community will be determined using a specific technique to stain individual microbial cells and epifluorescence microscopy. Functional genes will be quantified indicative for carbon, nitrogen and sulfur cycling in marine snow particles. Taken together, ARTEMIS should elucidate the microspatial architecture of microbial communities during the succession of marine snow, particularly the changed related to increasing oxygen depletion in the interior of marine snow. As such, the results of ARTEMIS should allow extrapolation on processes occurring on marine snow in the less accessible open ocean.

Within the project ARTEMIS, the microbial colonization and community composition of detrital particles in the Adriatic Sea was investigated. The focus was on marine snow and plastic particles. Marine snow is typically generated from decaying phytoplankton blooms. The microbial community composition on marine snow is fundamentally different from that on marine plastic particles. Marine plastics were typically colonized by bacterial know to degrade hydrocarbons.