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    - Jeanne Defoi / Martinique Water office

    "In Guadeloupe and Martinique, the conditions in rivers, e.g. steep slopes, low discharges, insular tropical context, made it necessary to develop specific bioassessment tools in a very short time. The work started in 2008 on diatoms and macroinvertebrates..."

A complete set of bioassessment tools to determine the status of surface waters

In the run-up to the second WFD management cycle (2016-2021), many of the WFD-compliant bioassessment tools legally required to determine the ecological status of surface waters were finalised in 2012. Considerable R&D effort was also put into creating the necessary tools for aquatic environments in the overseas territories.

The European water framework directive (WFD) requires that the Member States set up bioassessment tools to determine the ecological status of aquatic environments. Each tool is based on a biological community, e.g. microscopic algae (phytobenthos, phytoplankton), aquatic macrophytes, benthic invertebrates and fish. Based on various biological metrics, e.g. the number of species present, their relative abundance, the size of certain populations, etc., the tools serve to quantify the status of the studied environment with respect to a «reference» environment free of any anthropogenic pressures. In continental France, the development of most of these complex tools was terminated in 2012, following years of intense work by the scientific community and managers of aquatic environments.

A complete toolbox for rivers and lakes in continental France

For French rivers, the work done by Irstea improved existing tools and/or made them fully WFD-compliant. All the necessary tools have now been validated by the scientific community and the IBD 2007 diatom biological index (microscopic algae), the IBMR river macrophytic biological index (aquatic plants), the I2M2 multi-metric invertebrate index (benthic invertebrates) and the IPR+ river fish index will serve for assessments during the second WFD cycle (2016-2021). That is also the case for a set of bioassessment tools developed ex nihilo or using the very small number of existing techniques for lakes. This work, coordinated by the Onema- Irstea centre in Aix-en-Provence in conjunction with the Irstea CARMA team in Bordeaux, produced the IPLAC lake phytoplanktonic index, the IBML lake macrophytic biological index, the IMAIL lake macroinvertebrate index and the IIL lake fish index. The assessment results produced by these tools, particularly those for rivers, have been undergoing tests in the river basins since the middle of 2012. In early 2014, they will be included in the regulation defining the assessment rules for water status over the period 2016 to 2021. In parallel, work is underway to fill out the system with tools for heavily modified water bodies and artificial water bodies. The goal is to define a target status for these complex water bodies and create suitable bioassessment tools for the third WFD management cycle.

The Water offices mobilised overseas

WFD requirements apply without restriction and according to the same timetable to the French overseas territories whose aquatic environments are home to very specific and often highly diversified fauna and flora (Amazonian rivers and coral reefs are remarkable reservoirs of biodiversity). The development of suitable bioassessment tools constituted a true scientific challenge, due notably to a lack of knowledge on the existing pressures and species. It was carried out in a short number of years by the local Water offices in conjunction with national research institutes (Irstea, IRD, CNRS, etc.) and with technical and financial support from Onema. For example on Réunion island, the programme launched in 2008 produced in 2012 a set of WFD-compliant bioassessment tools that are now being validated by aquaticenvironment managers. One tool based on diatoms (microscopic algae) informs on the general physical-chemical quality of the environment, whereas two others using fish and benthic macroinvertebrates are sensitive to the physical degradation of habitats. Irstea, with technical coordination by Onema, is currently studying whether a tool using macrophytes would be of use, given the highly irregular hydrological regimes of overseas rivers. This study is being carried out in all the French overseas territories.Some 13 000 kilometres from Réunion, two bioassessment tools were developed for both Martinique and Guadeloupe, whose ecosystems are fairly similar. Intended for rivers, the first tool is based on diatoms and the second on macroinvertebrates (see below). The two tools are now being transferred to the technicians in the field and should be ready for the second WFD cycle. Bioassessment tools are also available for certain types of water body in Guiana, but they must be improved in view of the third WFD cycle. Finally, a research partnership between INRA and Onema was started in 2012 to develop bioassessment tools tailored specifically for the rivers of Mayotte, another overseas territory. The tools developed for Mayotte will call extensively on innovative methods including experimental DNA and genetic techniques to monitor and assess the ecological quality of environments.

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