Towards a better understanding of the ecology of Hemimysis anomala, an invasive small pelagic crustacean alien, in Lake Geneva
Résumé
The bloody-red shrimp (Hemimysis anomala) is an invasive crustacean belonging to the Mysidae family and native to the Ponto-Caspian region (Eastern Europe). It has recently settled in some peri-alpine lakes, among which the largest natural deep ecosystem in occidental Europe, e.g. Lake Geneva. The proliferation of this species can have a variety of impacts on both native species and the functioning of lake ecosystems, while considering its planktonophagous diet, in one hand, and because it constitutes a potential prey for fish, in another hand. Due to its nocturnal activity, as individuals hide during the day in interstitial spaces (e.g. cavities, under stones, wrecks, etc…), the assessment of its abundance and in-situ behavior remains difficult to obtain with traditional sampling methods. Scuba diving helped us to (i) detect and follow the animal in a variety of locations and habitats, (ii) make pictures and videos, (iii) sample animals with a designed and dedicated sampler for further analysis (molecular, isotope, …), (iv) instrument a site with high-resolution acoustic and visible/infrared cameras. This talk is the opportunity to present a variety of results dealing with the habitat, abundance, dynamics, swarm behavior and biotic interactions of the bloody-red shrimp.