Recent Distribution of the Freshwater Crustacean Asellus Aquaticus (Linnaeus, 1758) (Isopoda; Crustacea) in Serbia (2007-2013 Period) - Page 03

Results and Discussion

According to our results, A. aquaticus is widely distributed throughout the investigated area. The species was recorded at 65 sampling sites situated at 45 watercourses and one reservoir (Grlište) (Figure 1). Most of localities where this crustacean was recorded, by the national watercourse typology, belong to Type 3 rivers - small to medium size rivers to 500 m.a.s.l. altitude, with domination of large fractions of substrate (Official Gazette of the Republic of Serbia, 74/2011). Asellus aquaticus was found to be the dominant crustacean species at 26 localities situated at 24 watercourses in Serbia in the investigated period: Gunjevac/Ub River, Šarbane/Ub River, Crvena Jabuka/Tamnava River, Piroman/Tamnava River, Ćuprija/Tamnava River, Bridge on Ibar highway/Beljanica River, Beli Brod/Kolubara River, Paraćin/Crnica River, Rogot/Lepenica River, Orašje/Jasenica River, Šengolj/Đetinja River, Brđani/Despotovica River, Bivolje/Rasina River, Raška/Raška River, Pukovac/Pusta Reka River, Bujanovac/Binačka Morava River, Ristovac/Južna Morava River, Trnovče/Velika Morava River, Knjaževac/Svrljiški Timok River, Vražogrnac/Crni Timok River, Inđija/Inđijski potok Stream, Starčevo/Nadel Canal, Hetin/Stari Begej Canal, Srpski Itebej/Plovni Begej River, Novi Bečej/Tisa River, Novi Bečej/DTD Canal, Melenci/DTD Canal, Banatska Palanka/DTD Canal and Novo Miloševo/Kikinda Canal. 

In Vojvodina, A. aquaticus was present at 16 sampling sites located at 15 watercourses (mainly artificial water bodies - stretches of the Danube-Tisa-Danube (DTD) Canal and watercourses Type 5 - Pannonian Plain watercourses, except those belonging to Type 1 (Official Gazette of the Republic of Serbia, 74/2011). Smaller watercourses with plenty of detritus and riparian vegetation where found to be typical habitats (Figure 2), which corresponds to literature data (Williams, 1962; Graca et al, 1994).

Although in investigated area other representatives of asellids, such is genus Proasellus, could be present, in this investigation their presence was not confirmed. Morphologically all found specimens were more or less uniform, and belong to type species A. aquaticus (Figure 3).

As conclusion, regarding high tolerance to organic pollution, and high overall adaptability, such wide distribution of this taxon is expected. It is confirmed as an important member of freshwater macroinvertebrate communities in smaller moderately polluted and organic rich, streams, such as Pannonian streams and canals, but it was recorded in some clean mountain watercourses, such as Sopotnica River, confirming its adaptability. Obtained data, along with future detailed investigations, will lead to better understanding of this species diversity, resulting in more effective involvement of this species in a system of freshwater ecological status assessment.

 

Fig02
Figure 2: The Nadel Canal (Starčevo locality) – typical habitat of A.aquaticus in Serbia.

Fig03
Figure 3: Specimen of A.aquaticus (a. the whole specimen; b. the head) from Serbia (the Nadel Canal).