Response of freshwater mussel recruitment to hydrological changes in a eutrophic floodplain lake

English. Although eutrophication of freshwaters is a natural process, the human impact often leads to inland waters be-coming overloadedwith nutrients, impoverishingmanyvaluableand vanishinghabitats, such asfloodplainlakes.These changes need to be reversed if the occurrence of endangered aquatic species is to be restored. In this paperwe analyse the impact of a change in the water regime of a naturally eutrophicfloodplain lake, which harbours alarge diversity of Unionidae (large freshwater mussels), a globally threatened taxonomic group that provides im-portant ecosystem functions and services. We found that a slight increase in the discharge from this waterbody,following the construction of an additional outflow pipe, positively influenced recruitment in three of thefivemussel species inhabiting the lake. We also found that, after the construction of this additional outflow, theniches of juveniles ofAnodonta cygneaandUniospp. changed, revealing differences in their hydrological require-ments. Our results suggest that, as in lotic habitats, complex hydraulic parameters are highly significant tounionid mussels in lentic conditions.

English. Flow velocity, Juveniles, Lentic conditions, Microhabitats, Reynolds number

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