Bioremediation of high organic load lagoon sediments: compost addition and priming effects.

Lagoons are often affected by eutrophication phenomena, due to their shallow nature, high productivity, weak hydrodynamism and anthropic exploitation. Bioremediation techniques have been widely used in the treatment of chemical pollution; however, no information is available on the use of bioremediation of organic-rich sediments. In the present study, we investigated the priming effects following compost addition to organic-rich lagoon sediments, and the effects of this compost addition on degradation and cycling of organic detritus, transfer of organic matter to higher trophic levels, and in situ prokaryotic community structure. There was a positive response to treatment, particularly during the first days after compost addition. The compost had a stimulating effect on degradation activity of the prokaryotic community. This occurred despite an increase in available organic matter, as the community was more efficient at removing it. These data are supported by the prokaryotic community structure analysis, which revealed no changes in the in situ community following compost addition. This priming effect enhancement through compost addition represents an efficient method to treat organic-rich sediments.