The Principal Peril Facing Crayfish and Fish in Auvergne Rhône-Alpes: Climate Change – Enviscope.

The Regional Red Lists make it possible to take into account and anticipate the increasing pressures, consequences of climate change on the aquatic environments of Auvergne Rhône-Alpes.

Lhe impact of climate change, human and industrial interventions on the waterways and rivers of Auvergne-Rhône-Alpes, is probably not sufficiently anticipated. The very negative and very worrying results of the red lists regional “ fish and crayfish” and the results of the updating of the lists of ZNIEFF (Natural Interest, Ecological, Floristic and Faunistic Zones) in Auvergne-Rhône-Alpes show the threats to aquatic environments (streams, torrents, rivers , lakes, ponds, etc.) . The heritage value of these environments and their hosts is indisputable.

The contributors to the studies carried out over the past two years have the factual elements to raise the debates and reflections on the causes of this decline and to envisage solutions for the future of fish species and more generally of aquatic environments.

The rivers of Auvergne Rhône-Alpesva will experience a drop in average interannual flows of around -10% to -40%. The drop will be -10 to -60% in low water flows in the Rhône basin by 2100, according to a study by the Rhône Mediterranean Corsica Water Agency conducted by Aubé D. in 2016). The increase in air temperatures observed in the region is of the order of +1.9°C to +2.4°C over the period 1959-2018 according to the Regional Climate Change Observatory (ORCAE, 2019 ). A increase in water temperature will also occur. These pressures will be very impactful or even decisive for the maintenance of several species, in particular particular for salmonids, other migratory species and Apron.

The 2022 update of the inventory of Natural Areas of Ecological, Faunistic and Floristic Interest (ZNIEFF) in the Auvergne-Rhône-Alpes region confirms the trends. The development of regional red lists Pisces » et « crayfish was the opportunity and the working basis required to update the already existing ZNIEFF lists and extend them to the presence of fish and crayfish. Initiated in 2003, the updating of the lists of determining species and habitats of the ZNIEFF requires an update of these lists, in particular because of the programs for the improvement and synthesis of knowledge of biodiversity developed over the past ten years (Natura 2000 , national action plans, regional red lists, etc.).

The update covered 505 ZNIEFF were newly enriched (no fish data was available) data relating to fish species and 146 are maintained (species still present), in comparison of 305 ZNIEFF identified so far. The visibility of pisci speciescoles is therefore greatly increased in the territory. Forthe crayfish, the maintenance of many white-clawed crayfish populations seems to be seriously compromised. 217 ZNIEFFs are identified with the presence of white-clawed crayfish, the only determining crayfish species in the region. The obtained results reflect the same feeling of precariousness as those of the red list and the observations of the managers.