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Changes in Bacterial Diversity and Activity in Mediterranean Coastal Waters as Affected by Eutrophication



The determination of the spatial and temporal variations in genetic and phenotypic diversity of a microbial community.


The composition of bacterioplankton communities and the activity of its members is greatly influenced by the composition of the food web, hence the nutritional conditions of the environment. Changes occurring in the composition of a natural microbial population can only be assessed meaningfully when the undisturbed diversity of microorganisms and their activities are known. Only then is it possible to determine the influence of external factors on the microflora, such as shifts in physico-chemical conditions, pollutants or eutrophying compounds, and only then would it be possible to develop mechanisms to rapidly restore the original conditions.
Emphasis is placed on the evaluation of modifications in community structure and species composition at different stages of the eutrophication process. Initial base line studies carried out under natural and selected eutrophied conditions, such as the introduction of different nitrogen/phosphorous ratios and a variety of organic compounds, will allow the recognition of those parameters that will have the greatest impact on the natural community structure. In a second stage, experiments will be devised to relate differences in metabolic capabilities to the composition of the bacterioplankton community submitted to the one eutrophying condition that will induce the most important modifications. The validity of the conclusions originating from the comparison between diversity and cell activity obtained by in situ experiments will be tested in the North Adriatic Sea, or, depending on the availability of data from other ELOISE projects, to data obtained from other parts of the Mediterranean Sea.
Technical approach:

Artificial eutrophying conditions are imposed to an in situ simulated model with a mediterranean coastal water sample i.e. by an increase in inorganic or organic nutrients. Investigations of the community structure will concentrate on both the culturable community and those organisms that can not be cultured on the growth media and growth conditions provided. Modern molecular techniques will be applied for the assessment of diversity, e.g. PCR technology, cloning, sequencing and pattern recognitions methods. In parallel, methods will be used that quantitatively determine the physiologically active part of the community by using radioactive tracers, flow cytometry and analysis of ribosomal RNA.


Chabada will provide diagnostic tools for the assessment of bacterial species within the natural environment which appear to be quantitatively dominating and physiologically active. It will compare the methodologies for the rapid identification of indicator species under a given eutrophied condition which may lead to monitoring protocols for the assessment of the eutrophied stage of coastal marine environments.

Call for proposal

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1b,mascheroder weg 1b
38124 Braunschweig

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EU contribution
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Participants (5)