To complete the information provided by the benthos of soft substrate, whose correlation with pressures concerns mainly organic matter, another tool using the benthic fauna has been developed to better assess the impact of chemical pollution on the benthos.
The LPG-BIAF (UMR CNRS 6112), in collaboration with the French Water Agency, has developed a new and efficient biological index to evaluate the ecological quality of the marine environment based on benthic foraminifera fauna. These microorganisms, ubiquitous and abundant, respond rapidly and specifically to variations in environmental parameters. Moreover, their ability to fossilize makes them organisms that are very much used in paleoceanographic studies. Thus, they allow us to reconstruct the historical evolution of the ecological conditions of a site, a reconstruction rarely possible with other traditionally used indices.
Thanks to several oceanographic campaigns in the Mediterranean within the framework of the Water Framework Directive, an index has been constructed from the percentage of tolerant species, therefore indicative of stress, weighted by the granulometry of the sediment at the station studied (percentage of fine particles <63μm in the sediment). Thanks to this original and efficient “foraminiferous” index, we classify the different Mediterranean water bodies according to their ecological status.
Maps of the ecological status of Mediterranean coastal water bodies according to the foraminifera index are available for the years 2009, 2012 and 2015. To consult them, click on the “Access to maps” button, just below. The user has the possibility to download the study report of the 2012 WFD campaign (small ‘i’ next to the corresponding layer).
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