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Free living and particle associated microbial communities in the north Adriatic Sea along a transect from Rovinj to the Po river delta (CROSBI ID 588833)

Prilog sa skupa u zborniku | sažetak izlaganja sa skupa | međunarodna recenzija

Mina Bizic-Ionescu, Mina ; Zeder, Michael ; Ionescu, Danny ; Marshall, John ; Amann, Rudolf ; Fuchs, Bernard M. ; Najdek, Mirjana ; Orlić, Sandi Free living and particle associated microbial communities in the north Adriatic Sea along a transect from Rovinj to the Po river delta // 14th International Symposium on Microbial Ecology, The Power of the Small, The Book of Abstracts. Kopenhagen, 2012

Podaci o odgovornosti

Mina Bizic-Ionescu, Mina ; Zeder, Michael ; Ionescu, Danny ; Marshall, John ; Amann, Rudolf ; Fuchs, Bernard M. ; Najdek, Mirjana ; Orlić, Sandi

engleski

Free living and particle associated microbial communities in the north Adriatic Sea along a transect from Rovinj to the Po river delta

The shallow northern Adriatic is characterized by high seasonal variability of oceanographic and biological conditions, mainly due to climatic fluctuations and external nutrient input from the River Po. Due to complex hydrodynamics and freshwater influence the entire area is sensitive to pollution, eutrophication and undesirable phenomena: mucilage and anoxia events, particularly during summer when semi-enclosed circulation prevail. We collected samples during summer stratification (July 2011) when macroaggregates were abundantly present in the water column from 2 depths (10 m and 30 m) at 5 stations across the Po river Delta-Rovinj transect. We used FISH and DGGE to analyze the microbial community on these aggregates in comparison to its free-living counterpart. In addition using microsensors we analyzed the oxygen consumption of individual aggregates.DGGE fingerprinting suggests the river Po influences the free-living bacterial surface communities close to its estuary ; however, generally along the transect, adjunct surface or bottom samples cluster together. Within the particle associated community the surface communities generally cluster with the bottom community of the adjunct station suggesting horizontal transport of the particle during its sinking.Semi-automated microscopic analysis of 800 individual aggregates showed the aggregates closer to the sea bottom are smaller in size than those found above the thermocline. The correlation between the number of cells on an aggregate and its size was stronger at depth, suggesting in shallow water the number of colonizing microorganisms is determined by additional factors than available space. FISH analysis of the major phylogenetic groups showed different patterns between the surface depth and bottom both in the free living and the particle associated communities.Bacteroidetes made 25% of the surface community in the station closest to the Po River, decreasing across the transect. Interestingly the bottom community at the same station had the lowest percentage of Bacteroidetes (4%) and was equally dominated by Roseobacter and the Sar11 clade (7% and 10% respectively). The latter groups as well as the Crenarchaeota showed opposing patterns between surface and bottom also in the center of the transect, being more abundant at the surface. The particle associated communities were dominated by Roseobacter, Bacteroidetes and Gammaproteobacteria in the surface waters. On the bottom the Betaproteobacteria were significant as well increasing towards the gyre's center while Gammaproteobacteria decreased. Interestingly, the bottom particles were found more often to be associated with one main group.Microsensor measurements on individual aggregates showed photosynthetic activity to take place on the surface of the particles. Microscopy showed the extensive presence of small unicellular cyanobacteria attached to the particle. None of the aggregates tested reached anoxic condition even during un-naturally prolonged dark period suggesting the mucilage matrix is not rapidly respired by the colonizing communities. As the particles produce oxygen during the photic period and do not become anoxic during the night, we suggest that although abundant, macroaggregates as we have sampled do not lead to a significant oxygen minimum zone as long as the aggregates are in the shallow North Adriatic.

bacterial diversity; aggregates; north adriatic

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Podaci o prilogu

2012.

nije evidentirano

objavljeno

Podaci o matičnoj publikaciji

14th International Symposium on Microbial Ecology, The Power of the Small, The Book of Abstracts

Kopenhagen:

Podaci o skupu

14th International Symposium on Microbial Ecology

poster

19.08.2012-24.08.2012

Kopenhagen, Danska

Povezanost rada

Geologija, Biologija