Massive occurrences of gelatinous zooplankton in marine ecosystems, which are becoming more frequent in some environmetns, are often followed by mass die-offs, which provide ambient seawater microorganisms with a substantial amount of detrital organic matter. In order to better understand the fate of the detrital organic matter in marine ecosystem, we monitored the release as well as consumption of nutrients and dissolved organic matter compounds and the dynamics of the microbial community in a microcosm experiment with biodegradation and succession stage. Metabolically active specific bacterial populations were determined by coupling fluorescent in situ hybridization with Redox sensor green and L-homopropargylglycine. We followed the organic and inorganic nutrients released into the culture medium during the bacterial degradation of detritus. In the succession part of the experiment, in addition to the above listed parameters, we also measured the concentration of chlorophyll a. We found that the addition of detrital M. leidyi biomass results in the increase of the abundance of bacterial populations, as well as on their metabolic activity. Dissolved organic and inorganic nutrients were released into the culture medium, some part due to bacterial activity and some due to chemical dissolution. Nutrients released from the biodegradation of ctenophore detritus supported increase of the biomass of primary producers, indicated by an increase of chlorophyll a concentration in the succession part of the experiment. This shows that a fraction of ctenophore detrital organic matter can be transferred via microbies to support biomass increase of the primary producers.
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