High prevalence of the parasite Sphaerothecum destruens in the invasive topmouth gudgeon Pseudorasbora parva in the Netherlands, a potential threat to native freshwater fish

Frank Spikmans,Theo Van Alen,Gerard Van Der Velde,Huub Op Den Camp,Tomas Van Tongeren

doi:10.3391/ai.2013.8.3.12

Abstract

The prevalence of Sphaerothecum destruens, a pathogenic parasite, was studied in two wild populations of topmouth gudgeon (Pseudorasbora parva), an invasive freshwater fish non-native to the Netherlands. Using genetic markers and sequencing of the 18S rRNA gene, we showed the prevalence of this parasite to be 67 to 74%. Phylogenetic analysis demonstrated a high similarity with known sequences of S. destruens. The topmouth gudgeon, which functions as a healthy carrier of the pathogen, is rapidly colonizing the Netherlands, its expansion showing no signs of saturation yet. Both the presence of S. destruens and the rapid dispersal of the topmouth gudgeon are considered to constitute a high risk for native freshwater fish.

Highlights

Pathogens introduced by invasive species are a risk to native species and a threat to biodiversity (Daszak et al 2000)
In 1995, topmouth gudgeon was detected in the Rhine basin, but further dispersal was not recorded at that site during the following years
We report the first evidence of S. destruens being present in wild populations of topmouth gudgeon, with a prevalence of 67 to 74%

Summary

Introduction

Pathogens introduced by invasive species are a risk to native species and a threat to biodiversity (Daszak et al 2000). In the 1960s, the topmouth gudgeon was unintentionally imported from China and the former USSR together with herbivorous fish species [Hypophthalmichthys molitrix (Valenciennes, 1844), Hypophthalmichthys nobilis (Richardson, 1845) and Ctenopharyngodon idella (Valenciennes, 1844)], to fish farms in several eastern European countries, such as Romania, Hungary and Lithuania (Barus et al 1984; Gozlan 2012). In the Netherlands, this invader has been spreading across the country since its initial introduction in 1992. Rivers such as the Meuse function as a dispersal corridor, and high densities of topmouth gudgeon are found in the adjacent floodplain lakes (Pollux and Korosi 2006). Further expansion of the topmouth gudgeon towards European river basins can be expected (Copp et al 2009) and pose a high risk for the spread of pathogens such as Sphaerothecum destruens

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Conclusion