Among the factors included in the global changes that have led to the scarcity of the sturgeon, water contamination occupies a special place. A few studies have been carried out in contexts of very high with lethal effects, but apart from that, we have very little information on the possible effects of chronic contamination on the functioning of sturgeon populations.
In order to assess the tolerance of sturgeon embryos to substances widely used in agriculture, we carried out experiments with two fungicides used to treat certain crops and to preserve fruit and vegetables: Boscalid and Imazalil.
Two series of experiments were carried out with A. ruthenus embryos obtained by assisted reproduction at an INRAE station, in 2021 and 2022. We exposed freshly fertilized embryos, embryos at the end of yolk sac resorption, and larvae to environmental concentrations of Boscalid (1-10 µg/L) and Imazalil (1-10 µg/L).
The results showed that at these concentrations, there was no lethal effect and no impact on embryo hatching success.
Among the sublethal effects, we observed earlier hatchings at the highest concentrations tested of the two fungicides and at concentrations of 1µg/L, boscalid caused a reduction in the heart rate of the larvae. In addition, at the lowest concentrations, both fungicides induced abnormal growth and a change in larval swimming behaviour.
Genetic analyses carried out on larvae exposed to the highest concentrations of boscalid and imazalil revealed a disturbance in the metabolism of xenobiotics, lipids, steroids and mitochondria. Genes involved in development, neurotransmission and defence against oxidative stress were also altered.
This study showed that at environmental concentrations, boscalid and imazalil affected various physiological functions in A. ruthenus larvae. These two compounds could therefore pose a major risk to populations of sterlet and other sturgeon species.
 

ecotoxicology,embryo development,fungicides,effects