Biological Invasion of Fish Parasite Neoergasilus japonicus (Harada, 1930) (Copepoda: Ergasilidae) in Lake Grand Laoucien, France: A Field Study on Life Cycle Parameters and Reasons for Unusual High Population Density

Life

Remi Chappaz¹  Corinne Cuoc¹  Jean-Louis Jamet²  Dominique Jamet²  Victor Alekseev³ 

[1] INRAE, Aix Marseille University, UMR RECOVER, Case 36, 3 Place Victor Hugo, CEDEX 3, 13331 Marseille, France;Mediterranean Institute of Oceanology, Université de Toulon, AMU-UTLN UM110, CS 60584, CEDEX 9, 83041 Toulon, France;Zoological Institute, Russian Academy of Sciences, Universitetskaya Nab, 1, 199034 St. Petersburg, Russia;

关键词: high population density;    life cycle;    productivity;    local factors;    energetic flow;    microphytobenthos;   

DOI  :  10.3390/life11101100

来源: DOAJ

【 摘 要 】

The fish parasite, Neoergasilus japonicus (Harada, 1930), native to Eastern Siberia and the Amur River catchment area, invaded European water bodies in the middle of the last century, possibly due to the human-mediated distribution of fish in the Amur complex (i.e., the genera Hypophthalmichthys and Ctenopharyngodon). In the deep karst lake, Grand Laoucien (Marseille area, France), this species had an unusually high population density (from 1000 ind./ m³ in zooplankton to 4000 ind./ m³ in the nearshore area) during the free-living period of its life cycle. The annual cycle of N. japonicus includes a 5-month overwintering of fertilized females attached to fish fins and, following this, a five- to six-generation chain from March to November, when the free-living stages in the population alternate with parasite females which attach to their hosts for breeding. The population density of the parasites in zooplankton increased exponentially from spring to autumn, which positively correlated with temperature. We found a strong correlation between N. japonicus density and the community development of microphytobenthos, but not between N. japonicus and phyto- or zooplankton dynamics. The local contributing factors included a seasonal three-fold decrease in water levels and the development of anoxia in profundal waters, which led to a high ambient fish density and thus susceptibility to the parasite. Although the free-living parasite represented only 1% of zooplankton production, it consumed up to 25% of small invertebrate productivity. The maximum intensity of infection reached 140 parasites per fish, or 4.14 per g of weight. The high infection of fish with this parasite, in our opinion, indicated the danger it poses to the local ichthyofauna, which first encountered this new parasite.

【 授权许可】

Unknown