Non-indigenous invasive freshwater crustaceans (Crustacea: Malacostraca) in Slovakia

Boris Lipták1

 

 

 

1 The Institute of Zoology of the Slovak Academy of Sciences, Dúbravská cesta 9, SK-84506 Bratislava, Slovakia; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

 

Abstract

The paper synthesizes recent research results together with the earlier knowledge of the occurrence of non-indigenous invasive Malacostraca crustaceans in Slovakia, in which their invasion history and current distribution is evaluated. Altogether 17 non-indigenous species of class Malacostraca occur in the aquatic ecosystems in Slovakia, some of them are the most recent invaders. During the original research conducted in 2011, 8 species of exotic amphipods and one isopod were recorded. Indigenous amphipods were absent in the main course of the Danube River and its tributaries (the Lower Morava and Váh River) during the research. Further extension of the occurrence of the exotic Malacostraca fauna in the region is expected, decelerating the indigenous crustacean assemblages and altering the food web in the ecosystems. More crustacean invaders are expected to occur in the future, mainly as a consequence of aquarium trade, introduction via shipping and interconnection of the river systems.

Keywords: Non-indigenous species; Malacostraca; Danube River; Slovakia

 

Introduction

 

Invasive alien species are non-native species that are introduced to a new region of their occurrence or actively spread outside their original area and pose a risk to biodiversity. Invasive alien species are recognized to be the second most important threat to biodiversity at the global level, after direct habitat loss or destruction (Kettunen et al., 2008).

Several vectors are known to be responsible for species introduction. The most important introduction vector in the aquatic environment is shipping. There are several methods of species introduction associated with shipping: canals, ship's hull, ballast water and sediment transfer (Nehring, 2005). Introduction of the crustaceans to European inland waters has mainly been from: a) North America, Australia, and Asia; b) between diverse regions of the European mainland; and c) from the Ponto-Caspian Basin.

Range extensions of Ponto-Caspian aquatic species in Europe have been mainly facilitated by the interconnection of river basins, beginning as far back as the 17th century (Bij de Vaate et al., 2002). The connection of the Danube with the Main River was planned since the 8th century. The Main-Danube canal was officially opened in September 1992 and represents the most important connection that allows the faunal exchange between the Danube and the Rhine River Basins (Tittizer, 1997).

This connection is a part of the Southern invasion corridor and is a pathway that significantly affects our indigenous freshwater assemblages. Furthermore, the Rhine River is a final part of the Central invasion corridor as well, allowing exchange of fauna from an extensive range of water courses in Northern and Eastern Europe. These connections of the European river systems represent the main dispersal routes for the Ponto-Caspian species. The connection between the Southern and Central invasive corridor is one of the most important connections allowing the dispersion of the species, thus the colonization of the whole European continent alike (see Jażdżewski, 1980; Bij de Vaate et al., 2002).

Several compilation papers were published in regard to the non-indigenous fauna presenting a check-lists of aquatic alien species for specific countries (Grigorovich et al., 2002; Gollasch and Nehring, 2006; Alexandrov et al., 2007; Puky et al., 2008; Semenchenko et al., 2009) or a list of non-indigenous crustaceans in European inland waters (e.g. Holdich and Pöckl, 2007). In relation to non-indigenous fauna occurring in Slovakia, only partial studies were published. Recent more complex studies dealing with crustaceans were conducted by Nesemann et al. (1995) and Brtek (2001). Recently, in the light of new data and research, a check-list of non-indigenous invasive species of the class Malacostraca occurring in the Slovak part of the Danube River and its tributaries in Slovakia with regard to their distribution was prepared and is presented in this paper.

 

Material and Methods

In the current study, material was sampled in the littoral zone of the rivers by the kick and sweep method. Samples were taken from 24 sites distributed across the whole section of the Danube River and some of its tributaries in Slovakia in 2011. Sampling sites with corresponding characteristics are described in Table 1.

 

Table 1: Sampling sites with corresponding data
Tab01

 

Material was fixed in 96% ethanol and evaluated under the stereomicroscope. Species were identified according to publications of Brtek (2001, 2003), Jażdżewski and Konopacka (1996) and Borza et al. (2010). The nomenclature is in accordance with the Fauna Europaea (Boxshall, 2012). The crustacean specimens are deposited at the Institute of Zoology of the Slovak Academy of Sciences in Bratislava.