Author: Lorena  Selak,  research assistant (Ruđer Bošković Institute)

Designation: 

Description:
In the semi-arid Mediterranean region, limited freshwater resources are experiencing increased pressures due to the growing water demand for irrigation purposes, prolonged droughts and short but intense precipitation events caused by climate change. In the shallow coastal water bodies such as Lake Vrana, the consequence of such events is manifested in the form of precipitation-evaporation imbalance which can distort the nutrient flux and eventually increase their trophic state. To estimate the impact of intensified seasonal changes on the lake’s microbial communities, we conducted spatio-temporal research. By applying the high-throughput 16S and 18S rDNA sequencing and the ultra-high resolution mass spectrometry to identify DOM on molecular formula level, we could link fresh DOM production by phytoplankton and its utilization by the free-living and particle-associated heterotrophic bacteria. Increased autochthonous DOM production occurred during the start of the dry season when the enhanced phytoplankton primary production manifested through high Chlorophyll a concentrations and Cyanobacterial relative abundance. The increasing bacterial functional group abundances involved in the organic matter degradation were triggered by the amount of the more bioavailable DOM. The dry period was marked with the slow salinization and the consequent marine species appearance. At the start of the wet period, the introduction of the allochthonous DOM and suspended particles via heavy rains caused the change in the particle-associated bacterial community.

Category: Scientific Program Abstract > Special Sessions > SS16 Microbe-organic matter interactions in aquatic systems: Advances and challenges