Recent Distribution of the Freshwater Crustacean Asellus Aquaticus (Linnaeus, 1758) (Isopoda; Crustacea) in Serbia (2007-2013 Period)

Boris Novaković1, Marija Ilić2, Margareta Kračun-Kolarević2, Bojana Tubić2, Nikola Marinković2, Jelena Đuknić2 and Vanja Marković2

 

 

1 Serbian Environmental Protection Agency, Ministry of Agriculture and Environmental Protection, Ruže Jovanovića 27a, 11160 Belgrade, E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

2 University of Belgrade, Institute for Biological Research "Siniša Stanković", Despota Stefana 142, 11060 Belgrade, Serbia; E-mail: This e-mail address is being protected from spambots. You need JavaScript enabled to view it

 

 

Abstract

Asellus aquaticus (Linnaeus, 1758) is the widespread and common Palearctic freshwater isopod found typically in the slow-current watercourses with rich organic debris. In Serbia there is a lack of data regarding both distribution and general ecology of this common freshwater species. This paper based on intensive field research covering almost entire territory of Serbia in 2007-2013 period aims to shed more light on the presence of this freshwater crustacean in our country. According to our findings, A. aquaticus is widely distributed throughout the investigated area. It was registered in vast variety of habitats, from large Pannonian lowland rivers, to small highland streams. It was found to be an important member of benthic communities and the dominant crustacean species in some habitats, such as small Pannonian streams. Regarding its high tolerance to organic pollution, and high overall adaptability, such wide distribution is expected. Presence of other A. aquaticus subspecies, besides type subspecies, as well as presence of Proasellus is not detected. Obtained data should result in more effective involvement of this species in a regional/national system of freshwater ecological status assessment.

Keywords: Asellus aquaticus, field research, habitat, distribution, Serbia.

 

Introduction

Asellus aquaticus (Linnaeus, 1758) is the widespread and common Palearctic freshwater isopod (Verovnik et al, 2005; Fauna Europea, 2013). As Verovnik et al (2004) speculate it probably originates in temperate northern Asia, because most of Asellus species have a predominantly east Palearctic distribution. The species is morphologically, ecologically and genetically variable with few subspecies distinguished, most of them found in karstic western Balkan (Verovnik et al, 2004). The nominotypic subspecies A. aquaticus aquaticus inhabits the most of species range, and in the further text it will be referred as A. aquaticus. In the Dinarides (mountainous and karstic areas) A. aquaticus carsicus is the most common subspecies (Sket, 1994). It differs from type subspecies by having an enlarged area of pleopods IV-V and shape of male pleopods I (Sket, 1994).

Besides Asellus genus, in the region of interest and neighboring countries, another representative of Asellidae is present – genus Proasellus Dudich 1925 (Fauna Europea, 2013). The main morphological differences, useful for separation of these two asellid genus, are head shape and colour pattern of head, as well as pleopod I in males i.e. pleopod II in females. An overview of these taxonomic characters is provided in Wouters & Vercauteren, 2009. This species exhibits sexual dimorphism, with males being larger, due to breeding with precopulatory mate-guarding, which is not uncommon in crustaceans (Ridley and Thompson, 1979). The maximum body length of males is up to 20 mm, while in females is up to 15 mm (Wouters & Vercauteren, 2009). Tolba and Holdich (1981) found that specimens from polluted sites have significantly lower body size, than those from clean sites.