Quantifying invasion dynamics: qPCR vs. ddPCR in monitoring the alien
invasive red-blood mysid Hemimysis anomala and its interaction with
perch in Lake Geneva
Abstract
1. Invasive alien species constitute a major threat for aquatic systems
due to their potential impact on endemic biodiversity, ecosystem
functioning, infrastructure, and possible sanitary issues. It is
therefore crucial to obtain information on their presence, abundance and
distribution. 2. The red blood mysid Hemimysis anomala, which originated
from the Ponto Caspian area, has recently settled in western European
lakes, including Lake Geneva. 3. Although divers have frequently
reported the presence and development of this small crustacean over the
last decade, no monitoring has yet been proposed. 4. During a period of
2.5 years, we tested and optimized an eDNA approach by comparing two PCR
techniques, quantitative and digital droplet PCR, to assess the
presence, abundance and dynamics of the animal as well as that of a
potential predator, the perch (Perca fluviatilis). 5. We show and
discuss the efficiency of the methods and reveal for the first time the
seasonal dynamics of Hemimysis anomala at a selected site in Lake
Geneva. We highlight, in agreement with diving observations that the
animal’s abundance is high in winter and declines rapidly in early
spring, concomitantly with temperature increase and perch presence.