Its native areas are the saline to brackish waters of the north-west Atlantic from Canada to the Gulf of Mexico ( Williams 1984). The species probably Selleckchem Daporinad reached Europe in ballast waters ( Rodriguez and Suarez, 2001 and Projecto-Garcia et
al., 2010). The first description from Europe comes from the Zuiderzee (the Netherlands) ( Maitland 1874). Thereafter, R. harrisii gradually spread into Germany, where it was recorded in 1936 ( Nehring & Leuchs 1999), and further east to Poland, where it appeared in 1951 ( Demel, 1953, Kujawa, 1957 and Michalski, 1957). Around 1953 R. harrisii was found in Denmark ( Jensen & Knudsen 2005). Since 1937, the Harris mud crab has also been found in the Ponto-Caspian region, e.g. in the Black and Caspian Seas, and in the Sea of Azov ( Zaitsev & Öztürk 2001). In Poland, R. harrisii was observed for the first time in 1951 in the Vistula Lagoon ( Demel 1953). In subsequent years, the species was reported in the Rivers Motława and Dead Vistula, where it managed to establish a self-sustaining population ( Kujawa, 1957 and Michalski, 1957). However, the occurrence of this mud crab in the Gulf of Gdańsk (southern Baltic Sea), which lies
near the above localities, seems controversial. On the one hand, Żmudziński (1961) and Pautsch selleck products et al. (1969) reported single specimens of R. harrisii in this basin; on the other, Szudarski (1963) reported Lumacaftor solubility dmso the absence of this species along the Polish Baltic coast during the Baltic-Belt Seas Committee in 1963. Apart from these two reports, no further information on the occurrence of the Harris mud crab in
the Gulf of Gdańsk came to light for the next 50 years (e.g. Kotwicki 1997). This applies to both planktonic (larval) and benthic (juvenile and adult) forms. We can therefore assume that the presence of single specimens of R. harrisii recorded in the Gulf of Gdańsk in the 1960s was probably accidental and that this species should really be regarded as a new component of the benthic communities in the Gulf of Gdańsk. Even though the species began to be observed more frequently in the Gulf of Gdańsk in the early 2000s ( Normant and Gibowicz, 2008 and Hegele-Drywa and Normant, 2009), no work was carried out targeting its occurrence in this basin. The appearance of R. harrisii in these waters is interesting, because for decades there have been stable populations of the species only in the nearby Dead Vistula and Vistula Lagoon ( Turoboyski, 1973, Janta, 1996, Rychter, 1997, Rychter, 1999 and Normant et al., 2004). It should also be noted that in 2007 the species appeared in large numbers in the Odra Estuary, where earlier it had hardly ever been recorded ( Czerniejewski and Rybczyk, 2008 and Czerniejewski, 2009).