Abstract
This contribution presents new data on the occurrence of the thick-shelled river mussel Unio crassus in the Stradomka river and its tributaries (S. Poland), not surveyed earlier. Live specimens and empty shells were found in 14 localities, mostly in the Stradomka river.
Highlights
The thick-shelled river mussel Unio crassus Philipsson, 1788 is a large unionid (Bivalvia: Unionidae) species
The thick-shelled river mussel used to be common in Europe, including Poland; later water pollution and river regulation led to a decrease in its abundance (Zając 2004, 2010)
I found 14 localities inhabited by U. crassus (Fig. 1, Table 1)
Summary
The thick-shelled river mussel Unio crassus Philipsson, 1788 is a large unionid (Bivalvia: Unionidae) species. Though it is morphologically similar to other unionid mussels with which it often co-occurs, several shell characters make it possible to identify the species in the field. U. crassus is regarded as a primarily fluviatile species. It inhabits lowland and upland rivers, both large and small (Lopes-Lima et al 2016). As in other species of Unio, its reproduction requires obligatory fish hosts; the larvae (glochidia) feed mostly on gills. Several fish species are hosts to glochidia of U. crassus: Leuciscus leuciscus, L. cephalus, Scardinius erythrophthalmus, Cottus gobio (Zając 2010 and references therein, Douda et al 2012, 2014), Phoxinus phoxinus and some other species (Taeubert et al 2012). The river bottom types preferred by U. crassus include sand, gravel, stone and clay
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
